The Nd:TiO_(2 )PEO coatings were formed in a phosphate-based electrolyte with the addition of Nd_(2)O_(3 )under the current density of 150,200,250 and 300 m A/cm^(2).SEM results showed that the micropores decreased on...The Nd:TiO_(2 )PEO coatings were formed in a phosphate-based electrolyte with the addition of Nd_(2)O_(3 )under the current density of 150,200,250 and 300 m A/cm^(2).SEM results showed that the micropores decreased on quantity and increased on scale with the increasing current density.AFM results revealed that the roughness of the coatings increased with the increasing current density.Phase and composition analysis showed that the Nd:TiO_(2) coatings were mainly composed of anatase and rutile phase.And the anatase phase content has reached the maximum value at the current density of 250 m A/cm^(2).XPS results indicated that Ti2p spin-orbit components of the Nd:TiO_(2) coatings are shifted towards higher binding energy,compared with the pure TiO_(2) coating,suggesting that some of the Nd^(3+)ions are combined with TiO_(2) lattice and led to dislocation.Photocatalytic test showed that the photocatalytic activity of Nd:TiO_(2) coatings varied in the same pattern with the anatase content variation in Nd:TiO_(2) coatings.The photocatalytic experiment results show that the photocatalytic activity of Nd:TiO_(2) coatings can be greatly enhanced with moderate amount of Nd^(3+).However,excessive amount of Nd^(3+)does not have an effective impact on the photoctalytic activity improvement.展开更多
The work investigates influence of the electrolyte conductivity on the onset of partial contact glow discharge electrolysis(CGDE)in a water electrolysis.Critical current density(CCD)and breakdown voltage were measured...The work investigates influence of the electrolyte conductivity on the onset of partial contact glow discharge electrolysis(CGDE)in a water electrolysis.Critical current density(CCD)and breakdown voltage were measured together with in situ observation of hydrogen bubble behavior,whose influence has not been focused on.For a fixed current during normal electrolysis,hydrogen coalescence adjacent to cathode surface was invigorated at a lower conductivity.Photographic analyses elucidated the hydrogen coalescence characteristics by quantifying size and population of detached hydrogen bubbles.The CCD increased about 104% within given range of conductivity(11.50-127.48 mS·cm^(-1))due to impaired bubble coalescence,which delays hydrogen film formation on the cathode.Meanwhile,decreasing trend of breakdown voltage was measured with increased conductivity showing maximum drop of 74%.It is concluded that onset of partial CGDE is directly affected by hydrodynamic bubble behaviors,whereas the electrolyte conductivity affects the bubble formation characteristics adjacent to cathode electrode.展开更多
Exploiting efficient urea oxidation reaction(UOR)and hydrogen evolution reaction(HER)catalysts are significant for energy-saving H2 production through urea-assisted water electrolysis,but it is still challenging.Herei...Exploiting efficient urea oxidation reaction(UOR)and hydrogen evolution reaction(HER)catalysts are significant for energy-saving H2 production through urea-assisted water electrolysis,but it is still challenging.Herein,carbon-encapsulated CoNi coupled with CoNiMoO(CoNi@CN-CoNiMoO)is prepared by solvothermal method and calcination to enhance the activity/stability of urea-assisted water electrolysis at large current density.It exhibits good activity for UOR(E10/1,000=1.29/1.40 V)and HER(E-10/-1000=-45/-245 mV)in 1.0 M KOH+0.5 M urea solution.For the UOR||HER system,CoNi@CN-CoNiMoO only needs 1.58 V at 500 mA cm-2 and shows good stability.Density functional theory calculation suggests that the strong electronic interaction at the interface between NiCo alloy and N-doping-carbon layers can optimize the adsorption/desorption energy of UOR/HER intermediates and accelerate the water dissociation,which can expedite urea decomposition and Volmer step,thus increasing the UOR and HER activity,respectively.This work provides a new solution to design UOR/HER catalysts for H2 production through urea-assisted water electrolysis.展开更多
Apparent critical current density(j_(Ac)^(a))of garnet all-solid-state lithium metal symmetric cells(ASSLSCs)is a fundamental parameter for designing all-solid-state lithium metal batteries.Nevertheless,how much the p...Apparent critical current density(j_(Ac)^(a))of garnet all-solid-state lithium metal symmetric cells(ASSLSCs)is a fundamental parameter for designing all-solid-state lithium metal batteries.Nevertheless,how much the possible maximum apparent current density that a given ASSLSC system can endure and how to reveal this potential still require study.Herein,a capacity perturbation strategy aiming to better measure the possible maximum j_(Ac)^(a)is proposed for the first time.With garnet-based plane-surface structure ASSLSCs as an exemplification,the j_(Ac)^(a)is quite small when the capacity is dramatically large.Under a perturbed capacity of 0.001 mA h cm^(-2),the j_(Ac)^(a)is determined to be as high as 2.35 mA cm^(-2)at room temperature.This investigation demonstrates that the capacity perturbation strategy is a feasible strategy for measuring the possible maximum j_(Ac)^(a)of Li/solid electrolyte interface,and hopefully provides good references to explore the critical current density of other types of electrochemical systems.展开更多
Developing highly effective and stable non-noble metalbased bifunctional catalyst working at high current density is an urgent issue for water electrolysis(WE).Herein,we prepare the N-doped graphene-decorated NiCo all...Developing highly effective and stable non-noble metalbased bifunctional catalyst working at high current density is an urgent issue for water electrolysis(WE).Herein,we prepare the N-doped graphene-decorated NiCo alloy coupled with mesoporous NiCoMoO nano-sheet grown on 3D nickel foam(NiCo@C-NiCoMoO/NF)for water splitting.NiCo@C-NiCoMoO/NF exhibits outstanding activity with low overpotentials for hydrogen and oxygen evolution reaction(HER:39/266 mV;OER:260/390 mV)at±10 and±1000 mA cm^(−2).More importantly,in 6.0 M KOH solution at 60℃ for WE,it only requires 1.90 V to reach 1000 mA cm−2 and shows excellent stability for 43 h,exhibiting the potential for actual application.The good performance can be assigned to N-doped graphene-decorated NiCo alloy and mesoporous NiCoMoO nano-sheet,which not only increase the intrinsic activity and expose abundant catalytic activity sites,but also enhance its chemical and mechanical stability.This work thus could provide a promising material for industrial hydrogen production.展开更多
The microplasma oxidation process of LY 12 Al alloy in Na2SiO3-KOH-NaAL2 system has been studied. The voltage-time curve of oxidation process is changed with the variation of current densities. The voltage breakdown a...The microplasma oxidation process of LY 12 Al alloy in Na2SiO3-KOH-NaAL2 system has been studied. The voltage-time curve of oxidation process is changed with the variation of current densities. The voltage breakdown and hardness of coating increase with increasing current density. The phase composition, morphologies, element and the distribution of ceramic coating are investigated by XRD, EPMA.展开更多
In the electro-deoxidation process,carbon parasitic reaction(CO_(3)^(2-)+4e–=C+3O^(2-))usually occurs when using carbon materials as the anode,which leads to increase of the carbon content in the final metal and decr...In the electro-deoxidation process,carbon parasitic reaction(CO_(3)^(2-)+4e–=C+3O^(2-))usually occurs when using carbon materials as the anode,which leads to increase of the carbon content in the final metal and decrease of the current efficiency of the process.The aim of this work is to reduce the negative effect of carbon parasitic reaction on the electrolysis process by adjusting anode current density.The results indicate that lower graphite anode area can achieve higher current density,which is helpful to increase the nucleation site of CO_(2) bubbles.Most of CO_(2) would be released from the anode instead of dissolution in the molten CaCl_(2) and reacting with O^(2-)to form CO_(3)^(2-),thus decreasing the carbon parasitic reaction of the process.Furthermore,the results of the compared experiments show that when the anode area decreases from 172.78 to 4.99 cm^(2),CO_(2) concentration in the released gases increases significantly,the carbon mass content in the final metal product decreased from 1.09%to 0.13%,and the current efficiency increased from 6.65%to 36.50%.This study determined a suitable anode current density range for reducing carbon parasitic reaction and provides a valuable reference for the selection of the anode in the electrolysis process.展开更多
The uniformity of current density distribution upon electrodes is one of the most important factors determining the lithium dendrites growth and cycling performance of lithium metal batteries(LMBs). Herein,current den...The uniformity of current density distribution upon electrodes is one of the most important factors determining the lithium dendrites growth and cycling performance of lithium metal batteries(LMBs). Herein,current density distributions of lithium metal anodes induced by various engineering factors, consisting of uneven cathode, electrolyte distribution, and different tab positions, and their effects on the electrochemical performance are investigated theoretically and experimentally in pouch cells. The deviation of current density in lithium metal anodes ranges from 2.47% to 196.18% due to the different levels of uneven cathode materials. However, the deviation is just 13.60% for different electrolyte thicknesses between cathodes and anodes, even a ten-layer separator in some positions. The maximum deviation for variational tab positions is only 0.17%. The nonuniformity in current density distribution results in severe dendrite growth issues and poor electrochemical performance of LMBs. This work not only confirms the direct correlation between the uneven current density distribution and lithium deposition behaviors, but also points out the decisive effects of cathode surface roughness on current distribution of anodes, to which more attentions should be paid in practical applications of LMBs.展开更多
Three-dimensional thermo-electrical finite element analyses were conducted to simulate the current density and temperature distributions in solder bump joints with different pad geometries.The effects of pad thickness...Three-dimensional thermo-electrical finite element analyses were conducted to simulate the current density and temperature distributions in solder bump joints with different pad geometries.The effects of pad thickness,diameter and shape on current density and temperate distributions were investigated respectively.It was found that pads with larger thickness or/and diameter could reduce current density and temperature in solder bump significantly.Pad shapes affected the current density and temperature distributions in solder bumps.The relatively low current density and temperature didn't occur in the bump joint with traditional rounded pad but occurred in bump joints with octagonal and nonagonal pads respectively.Therefore,optimized pad geometry may be designed to alleviate the current crowding effect and reduce the bump temperature,and therefore delay electromigration failure and increase the mean-time-to-failure.展开更多
Rational design and controllable synthesis of practical electrodes with high sta bility and activity at high current density for a hydrogen evolution reaction(HER)are critical for renewable and sustainable energy conv...Rational design and controllable synthesis of practical electrodes with high sta bility and activity at high current density for a hydrogen evolution reaction(HER)are critical for renewable and sustainable energy conversion.However,high-performance TiO_(2)-based electrocatalysts for HER are quite limited,and the cat alytic active centers still remain elusive.Herein,a simple strategy is demonstrated for the synthesis of TiO_(2)-carbon composite(TiO_(2)/C)with high HER performance and stability.The remarkable HER performance of TiO_(2)/C can be ascribed to the doping of carbon atoms,which leads to stronger hybridization of Ti 3d and O 2p orbitals,thus substantially improving the electrocatalytic efficiency.This study elucidates that the hydrogen evolution activity of oxide electrocatalysts can be largely improved by regulating their electronic structures by doping carbon atoms and also provides an effective strategy for designing heterostructured electro catalysts with high catalytic activity and stability at high current density for HER.展开更多
The empirically reported values of the critical current density (<i>j<sub>c</sub></i>) of Bi-2212 as 2.4 × 10<sup>5</sup> (<i>j<sub>c</sub></i><sub&g...The empirically reported values of the critical current density (<i>j<sub>c</sub></i>) of Bi-2212 as 2.4 × 10<sup>5</sup> (<i>j<sub>c</sub></i><sub>1</sub>;Sample 1) and 1.0 × 10<sup>6</sup> A/cm<sup>2</sup> (<i>j<sub>c</sub></i><sub>2</sub>;Sample 2) are intriguing because both of them correspond to the <i>same</i> values of the temperature <i>T</i> = 4.2 K and the applied magnetic field <i>H</i> = 12 × 10<sup>4</sup> G. This difference is conventionally attributed to such factors—not all of which are quantifiable—as the geometry, dimensions and the nature of dopants and the manners of preparation of the samples which cause their granular structures, grain boundaries, alignment of the grains and so on to differ. Based on the premise that the chemical potential <i>μ</i> subsumes most of these features, given herein is a novel explanation of the said results in terms of the values of <i>μ</i> of the two samples. This paper revisits the problem that was originally addressed in [Malik G.P., Varma V.S. (2020) WJCMP, 10, 53-70] in the more accurate framework of a subsequent paper [Malik G.P., Varma V.S. (2021) JSNM, 34, 1551-1561]. Besides, it distinguishes between the contributions of the electro-electron (<i>e-e</i>) and the hole-hole (<i>h-h</i>) pairs to <i>j<sub>c</sub></i>—a feature to which no heed was paid earlier. The essence of our findings is that the <i>j<sub>c</sub></i>s of the two samples differ because they are characterized by different values of the <i>primary</i> variables <i>μ<sub>i</sub></i><sub> </sub>and <img src="Edit_e1b831e9-dc51-4c3b-bd84-fa905e3e62b5.png" alt="" />, where <img src="Edit_1f775a80-30ab-447d-861f-afb4ba8fba6a.png" alt="" /> is the effective mass of a charge-carrier and <i>m<sub>e</sub></i><sub> </sub>is the free-electron mass and <i>i</i> = 1 and 2 denote Sample 1 and Sample 2, respectively. In the scenario of the charge-carriers being <i>predominantly h-h</i> pairs, the values of these parameters are estimated to be: <i>μ</i><sub>1</sub> ≈ 12.3 meV, <i>η</i><sub>1</sub> ≈ 0.58;<i>μ</i><sub>2</sub> ≈ 22.7 meV, <i>η</i><sub>2</sub> ≈ 0.94. Following from these and similar estimates when the charge-carriers are <i>e-e</i> pairs, given below for each sample are the detailed results for the values of the <i>secondary</i> variables viz. the number density of the charge-carriers and their critical velocity, the number of occupied Landau levels and the magnetic interaction parameter.展开更多
Metal sulfides are emerging highly active electrocatalysts for the oxygen evolution reaction(OER),but still suffer from the instability caused by their inevitable reconstruction,especially at industrial-level current ...Metal sulfides are emerging highly active electrocatalysts for the oxygen evolution reaction(OER),but still suffer from the instability caused by their inevitable reconstruction,especially at industrial-level current density.Here,it is discovered that Fe-incorporated Ni3S2 nanowires can deliver extraordinary durability with an ultralow potential degradation rate of 0.006 mV/h in alkaline electrolytes made with fresh water and seawater at a benchmark of 500 mA cm^(-2) while meeting the industrial activity requirement for overpotential less than 300 mV(290 mV).Systematic experiments and theoretical simulations suggest that after forming the S-doped NiFeOOH shell to boost intrinsic activity,Fe incorporation effectivelymitigates the reconstruction of the Ni_(3)S_(2) nanowire core by restraining Ni oxidation and S dissolution,justifying the performance.This work highlights the significance of circumventing reconstruction and provides a strategy to explore practical chalcogenides-based OER electrocatalysts.展开更多
Garnet-type solid-state batteries(SSBs)are considered to be one of the most promising candidates to realize next-generation lithium metal batteries with high energy density and safety.However,the dendrite-induced shor...Garnet-type solid-state batteries(SSBs)are considered to be one of the most promising candidates to realize next-generation lithium metal batteries with high energy density and safety.However,the dendrite-induced short-circuit and the poor interfacial contact impeded the practical application.Herein,interface engineering to achieve low interfacial resistance without high temperature calcination was developed,which Li_(6.4)La_(3)Zr_(1.4)Ta_(0.6)O_(12)(LLZTO)was simply coated with complex hydride(Li_(4)(BH_(4))_(3)I(3L1L))in various mass ratios n(Li_(4)(BH_(4))_(3)I)-(100−n)LLZTO(10≤n≤40).The interfacial conductivity increases by more than three orders of magnitude from 8.29×10^(−6)S·cm^(−1)to 1.10×10^(−2)S·cm^(−1).Symmetric Li cells exhibit a high critical current density(CCD)of 4.0 mA·cm^(−2) and an excellent cycling stability for 200 h at 4.0 mA·cm^(−2).SSBs with polymeric sulfur-polyacrylonitrile(SPAN)cathode achieve a high discharge capacity of 1149 mAh·g^(−1) with a capacity retention of 91%after 100 cycles(0.2 C).This attempt guides a simple yet efficient strategy for obtaining a stable Li/LLZTO interface,which would promote the development of solid-state batteries.展开更多
For in-depth investigation of the effect of low-frequency and DC remelting on the cleanliness of electroslag ingot,laboratory experiments were performed with different current densities and slag compositions to analyz...For in-depth investigation of the effect of low-frequency and DC remelting on the cleanliness of electroslag ingot,laboratory experiments were performed with different current densities and slag compositions to analyze the variation of oxygen content and inclusions in electroslag ingots.When 70%CaF_(2)+30% Al_(2)O_(3) binary slag is used for remelting,the current density has different effects on the cleanliness of electroslag ingots with different power supply modes.At the power frequency of 2 Hz,the oxygen content and the number of inclusions in the electroslag ingot increase significantly with the increase in remelting current density.By contrast,when consumable electrode connected to cathode(DCSP)or consumable electrode connected to anode(DCRP)is employed,the current density has little influence on ingot cleanliness.At the same current density,DCSP remelting has a more adverse effect on ingot cleanliness compared with DCRP remelting.Compared with the use of 70%CaF_(2)+30% Al_(2)O_(3) binary slag,using 60%CaF_(2)+20% Al_(2)O_(3) +20%CaO ternary slag significantly reduces the oxygen content and the number of inclusions in electroslag ingots,regardless of whether low-frequency or DC electroslag remelting occurs.The increase in oxygen and inclusions in electroslag ingot is caused by the electrolysis of Al_(2)O_(3) in the slag pool.The increased inclusions mainly involve Al_(2)O_(3) or Al-containing oxides with small size.As regards the power supply mode,low frequency,DCRP,and DCSP promote the electrolysis of Al_(2)O_(3) in the slag pool.From the perspective of remelting slag composition,the slag with lower Al2O3 content can reduce the pollution of electrolysis on electroslag ingot.展开更多
Developing the high activity,low cost and robust large-current-density-based electrocatalysts is of great significance for the industrial electrolytic water splitting.However,the current range of most reported materia...Developing the high activity,low cost and robust large-current-density-based electrocatalysts is of great significance for the industrial electrolytic water splitting.However,the current range of most reported materials is small,which makes it difficult for them to play their roles in practical applications.Here,a self-supported amorphous FexNi1-xMo O4/IF treated with ammonium fluoride (AF_(0.1)-FNMO/IF) is synthesized by one-step hydrothermal method.With the help of NH4F,AF_(0.1)-FNMO/IF exhibits a vertically cross-linked nanosheet with spherical structure.Electrochemical measurement shows that AF_(0.1)-FNMO/IF affords a large current density ordeal and only need low overpotentials of 289 and 345 m V to reach a current response of 500 m A/cm ^(2)for oxygen evolution reaction and hydrogen evolution reaction,respectively,together with long-time stability (both at 500,1000 and 2000 m A/cm ^(2)) in 1.0 mol/L KOH solution.Using it as bifunctional catalyst for overall water splitting,the current densities of 100,500,1000 and1500 m A/cm ^(2)are achieved at a cell voltage of 1.71,1.88,1.94 and 1.97 V with excellent durability,which is much better than that of most published electrodes.The work provides valuable insight for designing higher activity nickel iron-based molybdate catalysts with large current density.展开更多
The application of Li-O_(2)batteries(LOBs)with ultra-high theoretical energy density is limited due to the slow redox kinetics and serious side reactions,especially in high-rate cycles.Herein,CeO_(2)is constructed on ...The application of Li-O_(2)batteries(LOBs)with ultra-high theoretical energy density is limited due to the slow redox kinetics and serious side reactions,especially in high-rate cycles.Herein,CeO_(2)is constructed on the surface of Mn_(2)O_(3)through an interface engineering strategy,and Mn_(2)O_(3)@CeO_(2)heterojunction with good activity and stability at high current density is prepared.The interfacial properties of catalyst and formation mechanism of Li_(2)O_(2)are deeply studied by density functional theory(DFT)and experiments,revealing the charge-discharge reaction mechanism of LOBs.The results show that the strong electron coupling between Mn_(2)O_(3)and CeO_(2)can promote the formation of oxygen vacancies.Heterojunction combined with oxygen vacancy can improve the affinity for O_(2)and LiO_(2)reaction intermediates,inducing the formation of thin-film Li_(2)O_(2)with low potential and easy decomposition,thus improving the cycle stability at high current density.Consequently,it achieved a high specific capacity of 12545 at 1000 mA g^(-1)and good cyclability of 120 cycles at 4000 mA g^(-1).This work thus sheds light on designing efficient and stable catalysts for LOBs under high current density.展开更多
In the applications of superconducting materials,the critical current density J_(c)(B)is a crucial performance parameter.The conventional method of measuring J_(c)(B)of bulk superconductor is magnetization method.Howe...In the applications of superconducting materials,the critical current density J_(c)(B)is a crucial performance parameter.The conventional method of measuring J_(c)(B)of bulk superconductor is magnetization method.However,there are errors in the estimation of J_(c)(B)in the lower field,and the estimation is not applicable in the region where the magnetic field reverses.In this paper,J_(c)(B)of the bulk superconductor is determined by the hysteresis and magnetostriction loops with artificial neural network(ANN),respectively.Compared with double‐output ANN,the critical current density obtained by single‐output ANN is more accurate.Finally,the prediction results given by the hysteresis and magnetostriction loops are discussed.展开更多
Naturally occurring arsenic enrichment in groundwater poses a huge threat to human health.Air cathode electrocoagulation(ACEC)has recently been proposed to enhance As(Ⅲ)oxidation and lower energy consumption.In this ...Naturally occurring arsenic enrichment in groundwater poses a huge threat to human health.Air cathode electrocoagulation(ACEC)has recently been proposed to enhance As(Ⅲ)oxidation and lower energy consumption.In this study,ACEC,EC/O_(2) and EC/N_(2) were evaluated with different current densities from 1 to 8 mA/cm^(2) to investigate the effect on As(Ⅲ)removal in different redox environments.Current density had no appreciable effect on arsenic removal efficiency given the same charge in ACEC because the concentration ratio of Fe/H2O_(2) under different current densities remained stable.However,in EC/O_(2) and EC/N_(2),As(Ⅲ)removal was inhibited at higher current densities(4–8 mA/cm^(2)),likely because more Fe(Ⅱ)competed with As(Ⅲ)for the oxidant,leading to less effective oxidation of As(Ⅲ).In all EC systems,the$OH units generated per power consumption reached the highest value at the lowest current density.Compared with other EC systems,the ACEC system showed lower energy consumption at all current densities due to the low energy consumption of the electrode reaction and more free radical generation.A lower current density saved more energy at the expense of time,showing the trade-off relationship between energy consumption and removal time.The operation costs for As(Ⅲ)removal under optimal conditions were calculated as 0.028$/m^(3) for ACEC,0.030$/m^(3) for EC/O_(2),and 0.085$/m^(3) for EC/N_(2)展开更多
Developing high performance anode catalysts for oxygen evolution reaction (OER) and hydrazine oxidation reaction (HzOR) at large current density is an efficient pathway to produce hydrogen. Herein, we synthesize a FeW...Developing high performance anode catalysts for oxygen evolution reaction (OER) and hydrazine oxidation reaction (HzOR) at large current density is an efficient pathway to produce hydrogen. Herein, we synthesize a FeWO_(4)-WO_(3) heterostructure catalyst growing on nickel foam (FeWO_(4)-WO_(3)/NF) by a combination of hydrothermal and calcination method. It shows good catalytic activity with ultralow potentials for OER (ζ_(10) = 1.43 V, ζ_(1.000) = 1.56 V) and HzOR (ζ_(10) = −0.034 V, ζ_(1.000) = 0.164 V). Moreover, there is little performance degradation after being tested for _(10)0 h at 1,000 (OER) and _(10)0 (HzOR) mA·cm−2, indicating good stability. The superior performance could be attributed to the wolframite structure and heterostructure: The former provides a high electrical conductivity to ensure the electronic transfer capability, and the later induces interfacial electron redistribution to enhance the intrinsic activity and stability. The work offers a brand-new way to prepare good performance catalysts for OER and HzOR, especially at large current density.展开更多
Employing the alkaline water electrolysis system to generate hydrogen holds great prospects but still poses significant challenges,particularly for the construction of hydrogen evolution reaction(HER)catalysts operati...Employing the alkaline water electrolysis system to generate hydrogen holds great prospects but still poses significant challenges,particularly for the construction of hydrogen evolution reaction(HER)catalysts operating at ampere-level current density.Herein,the unique Ru and RuP_(2)dual nano-islands are deliberately implanted on N-doped carbon substrate(denoted as Ru-RuP_(2)/NC),in which a built-in electric field(BEF)is spontaneously generated between Ru-RuP_(2)dual nano-islands driven by their work function difference.Experimental and theoretical results unveil that such constructed BEF could serve as the driving force for triggering fast hydrogen spillover process on bridged Ru-RuP_(2)dual nano-islands,which could invalidate the inhibitory effect of high hydrogen coverage at ampere-level current density,and synchronously speed up the water dissociation on Ru nano-islands and hydrogen adsorption/desorption on RuP_(2)nano-islands through hydrogen spillover process.As a result,the Ru-RuP_(2)/NC affords an ultra-low overpotential of 218 mV to achieve 1.0 A·cm^(−2)along with the superior stability over 1000 h,holding the great promising prospect in practical applications at ampere-level current density.More importantly,this work is the first to advance the scientific understanding of the relationship between the constructed BEF and hydrogen spillover process,which could be enlightening for the rational design of the cost-effective alkaline HER catalysts at ampere-level current density.展开更多
基金Supported by the Open Project Foundation of Industrial Perception and Intelligent Manufacturing Equipment Engineering Research Center of Jiangsu Province (No. ZK220504)the Open Project Foundation of High-tech Key Laboratory of Agricultural Equipment and Intelligence of Jiangsu Province (No. MAET202104)+1 种基金the Open Project Foundation of Jiangsu Wind Power Engineering Technology Center (No. ZK220302)the Qing Lan Project of Jiangsu Province,China。
文摘The Nd:TiO_(2 )PEO coatings were formed in a phosphate-based electrolyte with the addition of Nd_(2)O_(3 )under the current density of 150,200,250 and 300 m A/cm^(2).SEM results showed that the micropores decreased on quantity and increased on scale with the increasing current density.AFM results revealed that the roughness of the coatings increased with the increasing current density.Phase and composition analysis showed that the Nd:TiO_(2) coatings were mainly composed of anatase and rutile phase.And the anatase phase content has reached the maximum value at the current density of 250 m A/cm^(2).XPS results indicated that Ti2p spin-orbit components of the Nd:TiO_(2) coatings are shifted towards higher binding energy,compared with the pure TiO_(2) coating,suggesting that some of the Nd^(3+)ions are combined with TiO_(2) lattice and led to dislocation.Photocatalytic test showed that the photocatalytic activity of Nd:TiO_(2) coatings varied in the same pattern with the anatase content variation in Nd:TiO_(2) coatings.The photocatalytic experiment results show that the photocatalytic activity of Nd:TiO_(2) coatings can be greatly enhanced with moderate amount of Nd^(3+).However,excessive amount of Nd^(3+)does not have an effective impact on the photoctalytic activity improvement.
基金sponsored by the Korean Ministry of Science and ICT(MSIT)supported by nuclear Research&Development program grant funded by the National Research Foundation(NRF)(2021M2D1A1084838)。
文摘The work investigates influence of the electrolyte conductivity on the onset of partial contact glow discharge electrolysis(CGDE)in a water electrolysis.Critical current density(CCD)and breakdown voltage were measured together with in situ observation of hydrogen bubble behavior,whose influence has not been focused on.For a fixed current during normal electrolysis,hydrogen coalescence adjacent to cathode surface was invigorated at a lower conductivity.Photographic analyses elucidated the hydrogen coalescence characteristics by quantifying size and population of detached hydrogen bubbles.The CCD increased about 104% within given range of conductivity(11.50-127.48 mS·cm^(-1))due to impaired bubble coalescence,which delays hydrogen film formation on the cathode.Meanwhile,decreasing trend of breakdown voltage was measured with increased conductivity showing maximum drop of 74%.It is concluded that onset of partial CGDE is directly affected by hydrodynamic bubble behaviors,whereas the electrolyte conductivity affects the bubble formation characteristics adjacent to cathode electrode.
基金the National Natural Science Foundation of China(22162004)the Excellent Scholars and Innovation Team of Guangxi Universities,the Innovation Project of Guangxi Graduate Education(YCBZ2022038)the High-performance Computing Platform of Guangxi University。
文摘Exploiting efficient urea oxidation reaction(UOR)and hydrogen evolution reaction(HER)catalysts are significant for energy-saving H2 production through urea-assisted water electrolysis,but it is still challenging.Herein,carbon-encapsulated CoNi coupled with CoNiMoO(CoNi@CN-CoNiMoO)is prepared by solvothermal method and calcination to enhance the activity/stability of urea-assisted water electrolysis at large current density.It exhibits good activity for UOR(E10/1,000=1.29/1.40 V)and HER(E-10/-1000=-45/-245 mV)in 1.0 M KOH+0.5 M urea solution.For the UOR||HER system,CoNi@CN-CoNiMoO only needs 1.58 V at 500 mA cm-2 and shows good stability.Density functional theory calculation suggests that the strong electronic interaction at the interface between NiCo alloy and N-doping-carbon layers can optimize the adsorption/desorption energy of UOR/HER intermediates and accelerate the water dissociation,which can expedite urea decomposition and Volmer step,thus increasing the UOR and HER activity,respectively.This work provides a new solution to design UOR/HER catalysts for H2 production through urea-assisted water electrolysis.
基金the financial support from the Natural Science Foundation for Distinguished Young Scholars of Hunan Province(2020JJ2047)the science and technology innovation Program of Hunan Province(2022RC3048)+2 种基金the Program of Huxiang Young Talents(2019RS2002)the Innovation-Driven Project of Central South University(2020CX027)the Fundamental Research Funds for the Central Universities of Central South University(2021zzts0125)。
文摘Apparent critical current density(j_(Ac)^(a))of garnet all-solid-state lithium metal symmetric cells(ASSLSCs)is a fundamental parameter for designing all-solid-state lithium metal batteries.Nevertheless,how much the possible maximum apparent current density that a given ASSLSC system can endure and how to reveal this potential still require study.Herein,a capacity perturbation strategy aiming to better measure the possible maximum j_(Ac)^(a)is proposed for the first time.With garnet-based plane-surface structure ASSLSCs as an exemplification,the j_(Ac)^(a)is quite small when the capacity is dramatically large.Under a perturbed capacity of 0.001 mA h cm^(-2),the j_(Ac)^(a)is determined to be as high as 2.35 mA cm^(-2)at room temperature.This investigation demonstrates that the capacity perturbation strategy is a feasible strategy for measuring the possible maximum j_(Ac)^(a)of Li/solid electrolyte interface,and hopefully provides good references to explore the critical current density of other types of electrochemical systems.
基金supported by the National Natural Science Foundation of China(21872040)the Hundred Talents Program of Guangxi Universitiesthe Excellent Scholars and Innovation Team of Guangxi Universities。
文摘Developing highly effective and stable non-noble metalbased bifunctional catalyst working at high current density is an urgent issue for water electrolysis(WE).Herein,we prepare the N-doped graphene-decorated NiCo alloy coupled with mesoporous NiCoMoO nano-sheet grown on 3D nickel foam(NiCo@C-NiCoMoO/NF)for water splitting.NiCo@C-NiCoMoO/NF exhibits outstanding activity with low overpotentials for hydrogen and oxygen evolution reaction(HER:39/266 mV;OER:260/390 mV)at±10 and±1000 mA cm^(−2).More importantly,in 6.0 M KOH solution at 60℃ for WE,it only requires 1.90 V to reach 1000 mA cm−2 and shows excellent stability for 43 h,exhibiting the potential for actual application.The good performance can be assigned to N-doped graphene-decorated NiCo alloy and mesoporous NiCoMoO nano-sheet,which not only increase the intrinsic activity and expose abundant catalytic activity sites,but also enhance its chemical and mechanical stability.This work thus could provide a promising material for industrial hydrogen production.
文摘The microplasma oxidation process of LY 12 Al alloy in Na2SiO3-KOH-NaAL2 system has been studied. The voltage-time curve of oxidation process is changed with the variation of current densities. The voltage breakdown and hardness of coating increase with increasing current density. The phase composition, morphologies, element and the distribution of ceramic coating are investigated by XRD, EPMA.
基金the National Natural Science Foundation of China(51674054)supported by the Chongqing Key Laboratory of Vanadium-Titanium Metallurgy and New Materials,Chongqing University,China.
文摘In the electro-deoxidation process,carbon parasitic reaction(CO_(3)^(2-)+4e–=C+3O^(2-))usually occurs when using carbon materials as the anode,which leads to increase of the carbon content in the final metal and decrease of the current efficiency of the process.The aim of this work is to reduce the negative effect of carbon parasitic reaction on the electrolysis process by adjusting anode current density.The results indicate that lower graphite anode area can achieve higher current density,which is helpful to increase the nucleation site of CO_(2) bubbles.Most of CO_(2) would be released from the anode instead of dissolution in the molten CaCl_(2) and reacting with O^(2-)to form CO_(3)^(2-),thus decreasing the carbon parasitic reaction of the process.Furthermore,the results of the compared experiments show that when the anode area decreases from 172.78 to 4.99 cm^(2),CO_(2) concentration in the released gases increases significantly,the carbon mass content in the final metal product decreased from 1.09%to 0.13%,and the current efficiency increased from 6.65%to 36.50%.This study determined a suitable anode current density range for reducing carbon parasitic reaction and provides a valuable reference for the selection of the anode in the electrolysis process.
基金supported by the National Natural Science Foundation of China (22075029, 22179070, U1932220)。
文摘The uniformity of current density distribution upon electrodes is one of the most important factors determining the lithium dendrites growth and cycling performance of lithium metal batteries(LMBs). Herein,current density distributions of lithium metal anodes induced by various engineering factors, consisting of uneven cathode, electrolyte distribution, and different tab positions, and their effects on the electrochemical performance are investigated theoretically and experimentally in pouch cells. The deviation of current density in lithium metal anodes ranges from 2.47% to 196.18% due to the different levels of uneven cathode materials. However, the deviation is just 13.60% for different electrolyte thicknesses between cathodes and anodes, even a ten-layer separator in some positions. The maximum deviation for variational tab positions is only 0.17%. The nonuniformity in current density distribution results in severe dendrite growth issues and poor electrochemical performance of LMBs. This work not only confirms the direct correlation between the uneven current density distribution and lithium deposition behaviors, but also points out the decisive effects of cathode surface roughness on current distribution of anodes, to which more attentions should be paid in practical applications of LMBs.
文摘Three-dimensional thermo-electrical finite element analyses were conducted to simulate the current density and temperature distributions in solder bump joints with different pad geometries.The effects of pad thickness,diameter and shape on current density and temperate distributions were investigated respectively.It was found that pads with larger thickness or/and diameter could reduce current density and temperature in solder bump significantly.Pad shapes affected the current density and temperature distributions in solder bumps.The relatively low current density and temperature didn't occur in the bump joint with traditional rounded pad but occurred in bump joints with octagonal and nonagonal pads respectively.Therefore,optimized pad geometry may be designed to alleviate the current crowding effect and reduce the bump temperature,and therefore delay electromigration failure and increase the mean-time-to-failure.
基金supported bythe Natural Scientific Foundation of China(Grants 21878001,22078002,21776001,21875001,21978002,21808002,22008001,and U1710114).
文摘Rational design and controllable synthesis of practical electrodes with high sta bility and activity at high current density for a hydrogen evolution reaction(HER)are critical for renewable and sustainable energy conversion.However,high-performance TiO_(2)-based electrocatalysts for HER are quite limited,and the cat alytic active centers still remain elusive.Herein,a simple strategy is demonstrated for the synthesis of TiO_(2)-carbon composite(TiO_(2)/C)with high HER performance and stability.The remarkable HER performance of TiO_(2)/C can be ascribed to the doping of carbon atoms,which leads to stronger hybridization of Ti 3d and O 2p orbitals,thus substantially improving the electrocatalytic efficiency.This study elucidates that the hydrogen evolution activity of oxide electrocatalysts can be largely improved by regulating their electronic structures by doping carbon atoms and also provides an effective strategy for designing heterostructured electro catalysts with high catalytic activity and stability at high current density for HER.
文摘The empirically reported values of the critical current density (<i>j<sub>c</sub></i>) of Bi-2212 as 2.4 × 10<sup>5</sup> (<i>j<sub>c</sub></i><sub>1</sub>;Sample 1) and 1.0 × 10<sup>6</sup> A/cm<sup>2</sup> (<i>j<sub>c</sub></i><sub>2</sub>;Sample 2) are intriguing because both of them correspond to the <i>same</i> values of the temperature <i>T</i> = 4.2 K and the applied magnetic field <i>H</i> = 12 × 10<sup>4</sup> G. This difference is conventionally attributed to such factors—not all of which are quantifiable—as the geometry, dimensions and the nature of dopants and the manners of preparation of the samples which cause their granular structures, grain boundaries, alignment of the grains and so on to differ. Based on the premise that the chemical potential <i>μ</i> subsumes most of these features, given herein is a novel explanation of the said results in terms of the values of <i>μ</i> of the two samples. This paper revisits the problem that was originally addressed in [Malik G.P., Varma V.S. (2020) WJCMP, 10, 53-70] in the more accurate framework of a subsequent paper [Malik G.P., Varma V.S. (2021) JSNM, 34, 1551-1561]. Besides, it distinguishes between the contributions of the electro-electron (<i>e-e</i>) and the hole-hole (<i>h-h</i>) pairs to <i>j<sub>c</sub></i>—a feature to which no heed was paid earlier. The essence of our findings is that the <i>j<sub>c</sub></i>s of the two samples differ because they are characterized by different values of the <i>primary</i> variables <i>μ<sub>i</sub></i><sub> </sub>and <img src="Edit_e1b831e9-dc51-4c3b-bd84-fa905e3e62b5.png" alt="" />, where <img src="Edit_1f775a80-30ab-447d-861f-afb4ba8fba6a.png" alt="" /> is the effective mass of a charge-carrier and <i>m<sub>e</sub></i><sub> </sub>is the free-electron mass and <i>i</i> = 1 and 2 denote Sample 1 and Sample 2, respectively. In the scenario of the charge-carriers being <i>predominantly h-h</i> pairs, the values of these parameters are estimated to be: <i>μ</i><sub>1</sub> ≈ 12.3 meV, <i>η</i><sub>1</sub> ≈ 0.58;<i>μ</i><sub>2</sub> ≈ 22.7 meV, <i>η</i><sub>2</sub> ≈ 0.94. Following from these and similar estimates when the charge-carriers are <i>e-e</i> pairs, given below for each sample are the detailed results for the values of the <i>secondary</i> variables viz. the number density of the charge-carriers and their critical velocity, the number of occupied Landau levels and the magnetic interaction parameter.
基金the National Key Research and Development Program of China(grant no.2021YFA1501002)National Natural Science Foundation of China(grant nos.22025208,22075300,and 21902162)+1 种基金DNL Cooperation Fund,CAS(grant no.DNL202008)Chinese Academy of Sciences,and Australian Research Council(grant no.DE220100746).
文摘Metal sulfides are emerging highly active electrocatalysts for the oxygen evolution reaction(OER),but still suffer from the instability caused by their inevitable reconstruction,especially at industrial-level current density.Here,it is discovered that Fe-incorporated Ni3S2 nanowires can deliver extraordinary durability with an ultralow potential degradation rate of 0.006 mV/h in alkaline electrolytes made with fresh water and seawater at a benchmark of 500 mA cm^(-2) while meeting the industrial activity requirement for overpotential less than 300 mV(290 mV).Systematic experiments and theoretical simulations suggest that after forming the S-doped NiFeOOH shell to boost intrinsic activity,Fe incorporation effectivelymitigates the reconstruction of the Ni_(3)S_(2) nanowire core by restraining Ni oxidation and S dissolution,justifying the performance.This work highlights the significance of circumventing reconstruction and provides a strategy to explore practical chalcogenides-based OER electrocatalysts.
基金This study was financially supported by the National Natural Science Foundation of China(Nos.52171180,51802154,and 51971065)the National Science Fund for Distinguished Young Scholars(No.51625102)+3 种基金the Innovation Program of Shanghai Municipal Education Commission(No.2019-01-07-00-07-E00028)the Fundamental Research Funds for the Central Universities(No.NG2022005)the Open Fund for Graduate Innovation Base in Nanjing University of Aeronautics and Astronautics(No.xcxjh20210612)partially supported by the Fundamental Research Funds for the Central Universities,NS2021043.
文摘Garnet-type solid-state batteries(SSBs)are considered to be one of the most promising candidates to realize next-generation lithium metal batteries with high energy density and safety.However,the dendrite-induced short-circuit and the poor interfacial contact impeded the practical application.Herein,interface engineering to achieve low interfacial resistance without high temperature calcination was developed,which Li_(6.4)La_(3)Zr_(1.4)Ta_(0.6)O_(12)(LLZTO)was simply coated with complex hydride(Li_(4)(BH_(4))_(3)I(3L1L))in various mass ratios n(Li_(4)(BH_(4))_(3)I)-(100−n)LLZTO(10≤n≤40).The interfacial conductivity increases by more than three orders of magnitude from 8.29×10^(−6)S·cm^(−1)to 1.10×10^(−2)S·cm^(−1).Symmetric Li cells exhibit a high critical current density(CCD)of 4.0 mA·cm^(−2) and an excellent cycling stability for 200 h at 4.0 mA·cm^(−2).SSBs with polymeric sulfur-polyacrylonitrile(SPAN)cathode achieve a high discharge capacity of 1149 mAh·g^(−1) with a capacity retention of 91%after 100 cycles(0.2 C).This attempt guides a simple yet efficient strategy for obtaining a stable Li/LLZTO interface,which would promote the development of solid-state batteries.
基金support from the National Natural Science Foundation of China(Grant Nos.52074002 and 51974002)Natural Science Foundation of Anhui Province(Grant No.2208085J37).
文摘For in-depth investigation of the effect of low-frequency and DC remelting on the cleanliness of electroslag ingot,laboratory experiments were performed with different current densities and slag compositions to analyze the variation of oxygen content and inclusions in electroslag ingots.When 70%CaF_(2)+30% Al_(2)O_(3) binary slag is used for remelting,the current density has different effects on the cleanliness of electroslag ingots with different power supply modes.At the power frequency of 2 Hz,the oxygen content and the number of inclusions in the electroslag ingot increase significantly with the increase in remelting current density.By contrast,when consumable electrode connected to cathode(DCSP)or consumable electrode connected to anode(DCRP)is employed,the current density has little influence on ingot cleanliness.At the same current density,DCSP remelting has a more adverse effect on ingot cleanliness compared with DCRP remelting.Compared with the use of 70%CaF_(2)+30% Al_(2)O_(3) binary slag,using 60%CaF_(2)+20% Al_(2)O_(3) +20%CaO ternary slag significantly reduces the oxygen content and the number of inclusions in electroslag ingots,regardless of whether low-frequency or DC electroslag remelting occurs.The increase in oxygen and inclusions in electroslag ingot is caused by the electrolysis of Al_(2)O_(3) in the slag pool.The increased inclusions mainly involve Al_(2)O_(3) or Al-containing oxides with small size.As regards the power supply mode,low frequency,DCRP,and DCSP promote the electrolysis of Al_(2)O_(3) in the slag pool.From the perspective of remelting slag composition,the slag with lower Al2O3 content can reduce the pollution of electrolysis on electroslag ingot.
基金financially supported by National Natural Science Foundation of China (No. 52174283)Shandong Provincial Natural Science Foundation (No. ZR2020MB044)+1 种基金Innovation Fund Project for Graduate Students of China University of Petroleum (East China) (No. 22CX04026A)the Fundameantal Research Funds for the Central Universities。
文摘Developing the high activity,low cost and robust large-current-density-based electrocatalysts is of great significance for the industrial electrolytic water splitting.However,the current range of most reported materials is small,which makes it difficult for them to play their roles in practical applications.Here,a self-supported amorphous FexNi1-xMo O4/IF treated with ammonium fluoride (AF_(0.1)-FNMO/IF) is synthesized by one-step hydrothermal method.With the help of NH4F,AF_(0.1)-FNMO/IF exhibits a vertically cross-linked nanosheet with spherical structure.Electrochemical measurement shows that AF_(0.1)-FNMO/IF affords a large current density ordeal and only need low overpotentials of 289 and 345 m V to reach a current response of 500 m A/cm ^(2)for oxygen evolution reaction and hydrogen evolution reaction,respectively,together with long-time stability (both at 500,1000 and 2000 m A/cm ^(2)) in 1.0 mol/L KOH solution.Using it as bifunctional catalyst for overall water splitting,the current densities of 100,500,1000 and1500 m A/cm ^(2)are achieved at a cell voltage of 1.71,1.88,1.94 and 1.97 V with excellent durability,which is much better than that of most published electrodes.The work provides valuable insight for designing higher activity nickel iron-based molybdate catalysts with large current density.
基金supported by the National Natural Science Foundation of China(22162004)the Natural Science Foundation of Guangxi Province(2022JJD120011)+1 种基金the Innovation Project of Guangxi Graduate Education(YCBZ2023012)the High-performance Computing Platform of Guangxi University.
文摘The application of Li-O_(2)batteries(LOBs)with ultra-high theoretical energy density is limited due to the slow redox kinetics and serious side reactions,especially in high-rate cycles.Herein,CeO_(2)is constructed on the surface of Mn_(2)O_(3)through an interface engineering strategy,and Mn_(2)O_(3)@CeO_(2)heterojunction with good activity and stability at high current density is prepared.The interfacial properties of catalyst and formation mechanism of Li_(2)O_(2)are deeply studied by density functional theory(DFT)and experiments,revealing the charge-discharge reaction mechanism of LOBs.The results show that the strong electron coupling between Mn_(2)O_(3)and CeO_(2)can promote the formation of oxygen vacancies.Heterojunction combined with oxygen vacancy can improve the affinity for O_(2)and LiO_(2)reaction intermediates,inducing the formation of thin-film Li_(2)O_(2)with low potential and easy decomposition,thus improving the cycle stability at high current density.Consequently,it achieved a high specific capacity of 12545 at 1000 mA g^(-1)and good cyclability of 120 cycles at 4000 mA g^(-1).This work thus sheds light on designing efficient and stable catalysts for LOBs under high current density.
基金support from the National Natural Science Foundation of China(Grant Nos.U2241267,12172155 and 11872195).
文摘In the applications of superconducting materials,the critical current density J_(c)(B)is a crucial performance parameter.The conventional method of measuring J_(c)(B)of bulk superconductor is magnetization method.However,there are errors in the estimation of J_(c)(B)in the lower field,and the estimation is not applicable in the region where the magnetic field reverses.In this paper,J_(c)(B)of the bulk superconductor is determined by the hysteresis and magnetostriction loops with artificial neural network(ANN),respectively.Compared with double‐output ANN,the critical current density obtained by single‐output ANN is more accurate.Finally,the prediction results given by the hysteresis and magnetostriction loops are discussed.
基金supported by National Natural Science Foundation of China(Grant No.42077171)the Special Fund of State Key Joint Laboratory of Environment Simulation and Pollution Control(No.20Y02ESPCT)+1 种基金the Basic Foresight Project of China Petroleum and Chemical Corporation(JC-2020-KF008)the support from Young Elite Scientist Sponsorship Program by CAST(No.2015QNRC001).
文摘Naturally occurring arsenic enrichment in groundwater poses a huge threat to human health.Air cathode electrocoagulation(ACEC)has recently been proposed to enhance As(Ⅲ)oxidation and lower energy consumption.In this study,ACEC,EC/O_(2) and EC/N_(2) were evaluated with different current densities from 1 to 8 mA/cm^(2) to investigate the effect on As(Ⅲ)removal in different redox environments.Current density had no appreciable effect on arsenic removal efficiency given the same charge in ACEC because the concentration ratio of Fe/H2O_(2) under different current densities remained stable.However,in EC/O_(2) and EC/N_(2),As(Ⅲ)removal was inhibited at higher current densities(4–8 mA/cm^(2)),likely because more Fe(Ⅱ)competed with As(Ⅲ)for the oxidant,leading to less effective oxidation of As(Ⅲ).In all EC systems,the$OH units generated per power consumption reached the highest value at the lowest current density.Compared with other EC systems,the ACEC system showed lower energy consumption at all current densities due to the low energy consumption of the electrode reaction and more free radical generation.A lower current density saved more energy at the expense of time,showing the trade-off relationship between energy consumption and removal time.The operation costs for As(Ⅲ)removal under optimal conditions were calculated as 0.028$/m^(3) for ACEC,0.030$/m^(3) for EC/O_(2),and 0.085$/m^(3) for EC/N_(2)
基金This work is supported by the National Natural Science Foundation of China(No.21872040)the Hundred Talents Program of Guangxi Universities,the Excellent Scholars and Innovation Team of Guangxi Universities,Guangxi Major Projects of Science and Technology(No.GXMPSTAA17202032),Guangxi Ba-Gui Scholars Program.
文摘Developing high performance anode catalysts for oxygen evolution reaction (OER) and hydrazine oxidation reaction (HzOR) at large current density is an efficient pathway to produce hydrogen. Herein, we synthesize a FeWO_(4)-WO_(3) heterostructure catalyst growing on nickel foam (FeWO_(4)-WO_(3)/NF) by a combination of hydrothermal and calcination method. It shows good catalytic activity with ultralow potentials for OER (ζ_(10) = 1.43 V, ζ_(1.000) = 1.56 V) and HzOR (ζ_(10) = −0.034 V, ζ_(1.000) = 0.164 V). Moreover, there is little performance degradation after being tested for _(10)0 h at 1,000 (OER) and _(10)0 (HzOR) mA·cm−2, indicating good stability. The superior performance could be attributed to the wolframite structure and heterostructure: The former provides a high electrical conductivity to ensure the electronic transfer capability, and the later induces interfacial electron redistribution to enhance the intrinsic activity and stability. The work offers a brand-new way to prepare good performance catalysts for OER and HzOR, especially at large current density.
基金the National Natural Science Foundation of China(Nos.22279124 and 52261145700)Shandong Province Natural Science Foundation(No.ZR2022ZD30)National Research Foundation of Korea(NRF)grant funded by the Korea government(MSIT)(Nos.NRF-2020R1A2C3004146 and RS-2023-00235596).
文摘Employing the alkaline water electrolysis system to generate hydrogen holds great prospects but still poses significant challenges,particularly for the construction of hydrogen evolution reaction(HER)catalysts operating at ampere-level current density.Herein,the unique Ru and RuP_(2)dual nano-islands are deliberately implanted on N-doped carbon substrate(denoted as Ru-RuP_(2)/NC),in which a built-in electric field(BEF)is spontaneously generated between Ru-RuP_(2)dual nano-islands driven by their work function difference.Experimental and theoretical results unveil that such constructed BEF could serve as the driving force for triggering fast hydrogen spillover process on bridged Ru-RuP_(2)dual nano-islands,which could invalidate the inhibitory effect of high hydrogen coverage at ampere-level current density,and synchronously speed up the water dissociation on Ru nano-islands and hydrogen adsorption/desorption on RuP_(2)nano-islands through hydrogen spillover process.As a result,the Ru-RuP_(2)/NC affords an ultra-low overpotential of 218 mV to achieve 1.0 A·cm^(−2)along with the superior stability over 1000 h,holding the great promising prospect in practical applications at ampere-level current density.More importantly,this work is the first to advance the scientific understanding of the relationship between the constructed BEF and hydrogen spillover process,which could be enlightening for the rational design of the cost-effective alkaline HER catalysts at ampere-level current density.
