Although the internal electric field(IEF)of photocatalysts is acknowledged as a potent driving force for photocharge separation,modulating the IEF intensity to achieve enhanced photocatalytic performances remains a ch...Although the internal electric field(IEF)of photocatalysts is acknowledged as a potent driving force for photocharge separation,modulating the IEF intensity to achieve enhanced photocatalytic performances remains a challenge.Herein,cuprous sulfide nanosheets with different Cu vacancy concentration were employed to study IEF modulation and corresponding direct charge transfer.Among the samples,Cu_(1.8)S nanosheets possessed intensified IEF intensity compared with those of Cu_(2)S and Cu_(1.95)S nanosheets,suggesting that an enhanced IEF intensity could be achieved by introducing more Cu vacancies.This intensified IEF of Cu_(1.8)S nanosheets induced numerous photogenerated electrons to migrate to its surface,and the dissociative electrons were then captured by Cu vacancies,resulting in efficient charge separation spatially.In addition,the Cu vacancies on Cu_(1.8)S nanosheets accumulated electrons as active sites to lower the energy barrier of rate-determining step of CO_(2)photoreduction,leading to the selective conversion of CO_(2)to CO.Herein,the manipulation of IEF intensity through Cu vacancy concentration regulation of cuprous sulfide photocatalysts for efficient charge separation has been discussed,providing a scientific strategy to rationally improve photocata lytic performances for solar energy conversion.展开更多
Constructing bismuth oxyhalide solid solutions with a single homogeneous phase have intrigued the research community;however,a deeper understanding of the intrinsic origin for improved bulk-charge separation is still ...Constructing bismuth oxyhalide solid solutions with a single homogeneous phase have intrigued the research community;however,a deeper understanding of the intrinsic origin for improved bulk-charge separation is still unclear.Herein,a series of Bi_(24)O_(31)Cl_(x)Br_(10-x) solid solutions with the same structural characteristics were synthesized by crystal structure regulation.Combining density functional theory calculation,Kelvin probe force microscopy,and zeta potential testing results,an enhanced internal electric field(IEF)intensity between[Bi_(24)O_(31)]and[X]layers was achieved by changing halogen types and ratios.This greatly facilitated bulk-charge separation and transfer efficiency,which is significant for the degradation of phenolic organic pollutants.Owing to the enhanced IEF intensity,the charge carrier density of Bi_(24)O_(31)Cl_(4)Br_(6) was 33.1 and 4.7 times stronger than that of Bi_(24)O_(31)Cl_(10) and Bi_(24)O_(31)Br_(10),respectively.Therefore,Bi24O31Cl4Br6 had an optimal photoactivity for the degradation of bisphenol A,which was 6.21 and 2.71 times higher than those of Bi_(24)O_(31)Cl_(10) and Bi_(24)O_(31)Br_(10),respectively.Thus,this study revealed the intrinsic mechanism of the solid solution strategy for photocatalytic performance enhancement with respect to an IEF.展开更多
Heteroatom doping has emerged as a prevailing strategy to enhance the storage of sodium ions in carbon materials.However,the underlying mechanism governing the performance enhancement remains undisclosed.Herein,we fab...Heteroatom doping has emerged as a prevailing strategy to enhance the storage of sodium ions in carbon materials.However,the underlying mechanism governing the performance enhancement remains undisclosed.Herein,we fabricated N/S co-doped carbon beaded fibers(S-N-CBFs),which exhibited glorious rate performance and durableness in Na+storage,showcasing no obvious capacity decay even after 3500 cycles.Furthermore,when used as anodes in sodium-ion capacitors,the S-N-CBFs delivered exceptional results,boasting a high energy density of 225 Wh·kg^(-1),superior power output of 22500 W·kg^(-1),and outstanding cycling stability with a capacity attenuation of merely 0.014%per cycle after 4000 cycles at 2 A·g^(-1).Mechanistic investigations revealed that the incorporation of both pyridinic N and pyrrolic N into the carbon matrix of S-N-CBFs induced internal electric fields(IEFs),with the former IEF being stronger than the latter,in conjunction with the doped S atom.Density functional theory calculations further unveiled that the intensity of the IEF directly influenced the adsorption of Na+,thereby resulting in the exceptional performances of S-N-CBFs as sodium-ion storage materials.This work uncovers the pivotal role of IEF in regulating the electronic structure of carbon materials and enhancing their Na^(+)storage capabilities,providing valuable insights for the development of more advanced electrode materials.展开更多
Energy storage devices are the hub of a multi-energy complementary distributed energy system.Hydrated salts are the most suitable phase change material for energy storage devices,but subcooling is the main obstacle to...Energy storage devices are the hub of a multi-energy complementary distributed energy system.Hydrated salts are the most suitable phase change material for energy storage devices,but subcooling is the main obstacle to their application.Nucleation requires a driving force so the use of nucleating agents alone does not reduce subcooling to a very low level.To address this issue,this paper first screened nucleating agents and then further reduced the subcooling of sodium acetate trihydrate in conjunction with stirring or direct current.The effects of rotor mass,rotational speed,direct current voltage,and electrode material on nucleation were analyzed.Finally,the stability of the composite phase change material in the presence of simultaneous stirring and energization was analyzed.The results showed that the addition of 1.5%in weight of disodium hydrogen phosphate dodecahydrate to sodium acetate trihydrate can reduce the subcooling to about 2.3℃.Continued addition of stirring or electricity can reduce the subcooling of sodium acetate trihydrate to within 0.5℃ or even eliminate it.The higher the momentum of the stirring,the better the improvement in subcooling,phase separation,and thermal conductivity.The higher the direct current voltage,the better the nucleation effect,but the electrode life will be lower.The silver electrode has the best nucleation effect.No new material was produced in the solution after 100 cycles in the presence of both stirring and direct current.The melting point of the phase change material was increased by 0.2℃ and the latent heat value decreased by 1.8%,still with good stability.The trace of deionized water should be added to the phase change material in subsequent studies to compensate for the consumption ofwaterby theanodicelution.展开更多
Stable potassium metal batteries(PMBs)are promising candidates for electrical energy storage due to their ability to reversibly store electrical energy at a low cost.However,dendritic growth and large volume changes h...Stable potassium metal batteries(PMBs)are promising candidates for electrical energy storage due to their ability to reversibly store electrical energy at a low cost.However,dendritic growth and large volume changes hinder their practical application.Here,referring to the morphology and structure of a virus,a bionic virus-like-carbon microsphere(BVC)was designed as the anode host for a PMB.A BVC with a three-dimensional structure can not only control the electric field,which can suppress dendrite formation,but can also provide a larger space to accommodate the volume change during the cycle progress.The designed potassium(K)metal anode exhibits excellent cycle life and stability(during 1800 h of repeated plating/stripping of K at a current density of 0.1 mA cm−2,K-BVC can realize a very stable K metal anode with low voltage hysteresis).Stable cyclability and improved rate capability can be realized in a full cell using Prussian blue over 400 cycles.This research provides a new idea for the development of stable K metal anodes and may pave the way for the practical application of next-generation metal batteries.展开更多
Conjugated linear polymers are promising metal-free photocatalysts for visible-light-driven photocatalytic water disinfection,but it was still bottlenecked by the insufficient photogenerated charge separation and tran...Conjugated linear polymers are promising metal-free photocatalysts for visible-light-driven photocatalytic water disinfection,but it was still bottlenecked by the insufficient photogenerated charge separation and transport(CST)process.Herein,we obtained the highly crystalline imine-linked conjugated linear poly-mer(ODA-BPAH)with a greatly enhanced CST process.The highly crystalline ODA-BPAH exhibited excel-lent broad-spectrum water disinfection efficiency up to 99.99999%in 1 h,which is among the reported highest of state-of-the-art photocatalysts.The crystallinity of ODA-BPAH was regulated by simply turn-ing the solvent and the experiment results revealed that the ODA-BPAH with high crystallinity exhibited higher internal electric field strength and photocatalytic performance than that with low crystallinity,which indicates that higher crystallinity in linear conjugated polymers contributes to superior CST ef-ficiency as well as the generation of reactive oxygen species.This work highlights the impact of poly-mer crystallinity on the internal electric field and proves that linear poly-imine could be a new type of promising metal-free photocatalyst for water treatment.展开更多
Heterojunction photocatalysts have shown considerable activities for organic pollutants degradation.However,the faint connection interface and inferior charge shift efficiency critically block the property of heteroju...Heterojunction photocatalysts have shown considerable activities for organic pollutants degradation.However,the faint connection interface and inferior charge shift efficiency critically block the property of heterojunction photocatalysis.Herein,Bi_(2)O_(2)S/NiFe_(2)O_(4) nanosheets heterojunction with ultrastrong inter-face interaction and high internal electric field are designed by an in-situ growth method.Tentative and theoretical consequences prove that the interfacial interaction and internal electric field not only act as the electron flow bridge but also decrease the electrons shift energy obstacle,thus speeding up electrons transfer and achieving effective spatial electron-hole separation.Therefore,a large amount of·O_(2)^(-)and holes as active species were generated.Remarkably,Bi_(2)O_(2) S/NiFe_(2)O_(4) establishes a considerably boosted photocatalytic performance for tetracycline degradation(0.032 min^(-1)),which is about 14.2-fold and 7.8-fold of the pristine BOS and NFO,respectively.This work provides a promising motivation for modulating charge transfer by interface control and internal electric field to boost photocatalytic performance.展开更多
Covalent organic frameworks(COFs)are promising materials for converting solar energy into green hydrogen.However,limited charge separation and transport in COFs impede their application in the photocatalytic hydrogen ...Covalent organic frameworks(COFs)are promising materials for converting solar energy into green hydrogen.However,limited charge separation and transport in COFs impede their application in the photocatalytic hydrogen evolution reaction(HER).In this study,the intrinsically tunable internal bond electric field(IBEF)at the imine bonds of COFs was manipulated to cooperate with the internal molecular electric field(IMEF)induced by the donor-acceptor(D-A)structure for an efficient HER.The aligned orientation of IBEF and IMEF resulted in a remarkable H_(2) evolution rate of 57.3 mmol·g^(-1)·h^(-1)on TNCA,which was approximately 520 times higher than that of TCNA(0.11 mmol·g^(-1)·h^(-1))with the opposing electric field orientation.The superposition of the dual electric fields enables the IBEF to function as an accelerating field for electron transfer,kinetically facilitat-ing the migration of photogenerated electrons from D to A.Furthermore,theoretical calculations indicate that the inhomogeneous charge distribution at the C and N atoms in TNCA not only pro-vides a strong driving force for carrier transfer but also effectively hinders the return of free elec-trons to the valence band,improving the utilization of photoelectrons.This strategy of fabricating dual electric fields in COFs offers a novel approach to designing photocatalysts for clean energy synthesis.展开更多
In this article, distributions of internal stress and internal electric fields around a triple point of ferroelectric polycrystals generated by the spontaneous deformation and spontaneous polarization were investigate...In this article, distributions of internal stress and internal electric fields around a triple point of ferroelectric polycrystals generated by the spontaneous deformation and spontaneous polarization were investigated. It was found that when all three grains consist of a single domain, the internal stresses and the internal electric fields do not vanish. Though it may be determined according to the principle of energy, the spontaneous configuration will not be unique without involving other conditions due to the symmetry of the crystal structure.展开更多
We have performed the first-principles calculation to investigate the origins of ferroelectricities and different po- larization behaviours of superlattices BaTiO3/SrTiO3 and PbTiO3/SrTiO3. The density of state （DOS...We have performed the first-principles calculation to investigate the origins of ferroelectricities and different po- larization behaviours of superlattices BaTiO3/SrTiO3 and PbTiO3/SrTiO3. The density of state （DOS） and electronic charge profiles show that there are strong hybridizations between atoms Ti and O and between atoms Pb and O which play very important roles in producing the ferroelectricities of superlattices BaTiO3/SrTiO3 and PbTiO3/SrTiO3. Ow- ing to the decline of internal electric field in SrTiO3 （ST） layer, the tetragonality and polarizations of superlattices decrease with increasing the fraction of SrTiO3 in the superlattices. We find that the polarization of PbTiO3/SrTiO3 is largerthan that of BaTiO3/SrTiO3 at the same ratio of components, because the polarization mismatch between PbTiO3 and SrTiO3 is larger than that between BaTiO3 and SrTiO3. The polarization and tetragonality are en- hanced with respect to those of bulk tetragonal BaTiO3 in the superlattices BaTiO3/SrTiO3, while the polarization and tetragonality are reduced with respect to those of bulk tetragonal PbTiO3 in superlattices PbTiO3/SrTiO3.展开更多
In this work,a novel NiP_(2)/g-C_(3)N_(4)heterojunction via homogeneous precipitation method assisted by thermal phosphorization reaction was designed and constructed,and the optimized sample showed the excellent phot...In this work,a novel NiP_(2)/g-C_(3)N_(4)heterojunction via homogeneous precipitation method assisted by thermal phosphorization reaction was designed and constructed,and the optimized sample showed the excellent photocatalytic H_(2)evolution activity under visible-light irradiation,which was nearly 112 times higher than that of pristine g-C_(3)N_(4)sample.Experimental characterizations and DFT calculations demonstrated that the NiP_(2)nanoparticles covered on the g-C_(3)N_(4)surface can form a built-in electric field at the interface to accelerate the transfer of photoexcited electrons from g-C_(3)N_(4)to NiP_(2),crucial for hindering the recombination of electron-hole pairs.Moreover,the energy barrier of hydrogen evolution reaction can also vastly reduce when combined NiP_(2)and g-C_(3)N_(4)to construct NiP_(2)/g-C_(3)N_(4)heterojunction.This work represents a method through combing experimental and theoretical tools to thoroughly investigate the mechanism of photocatalytic process.展开更多
Carbon nitride(C_(3)N_(4))is promising for photocatalytic hydrogen production,but photogenerated electrons and holes in C_(3)N_(4)usually tend to exist as excitons due to intrinsic Coulomb interactions making its phot...Carbon nitride(C_(3)N_(4))is promising for photocatalytic hydrogen production,but photogenerated electrons and holes in C_(3)N_(4)usually tend to exist as excitons due to intrinsic Coulomb interactions making its photocatalytic activity unsatisfactory.Herein,a well‐designed intramolecular C_(3)N_(4)‐based donor‐acceptor(D‐A)photocatalytic system was constructed to promote exciton dissociation.Due to its good chemical compatibility with melamine and appropriate sublimation property,2‐amino‐4,6‐dichloropyrimidine unit was chosen as the monomer to react with melamine to construct intramolecular D‐A system(CNCl_(x)).The hydrogen evolution rate of CNCl_(0.15)is 15.3 times higher than that of bulk C_(3)N_(4)under visible light irradiation,with apparent quantum efficiency of 13.6%at 420 nm.The enhanced activity is attributed to introduced electron‐withdrawing−Cl group as terminal group in the resulted CNCl_(x) samples,which can build internal electric field to promote the exciton dissociation into free electron and hole.In addition,lower work function value of CNCl_(x) samples indicates that internal electric field can help free electrons and holes transfer to the surface of CNCl_(x) samples for photocatalytic reaction.展开更多
Devising a desirable nano-heterostructured photoelectrode based on the charge transfer kinetics mechanism is a pivotal strategy for implementing efficient photoelectrocatalytic(PEC)technology,since the charge separati...Devising a desirable nano-heterostructured photoelectrode based on the charge transfer kinetics mechanism is a pivotal strategy for implementing efficient photoelectrocatalytic(PEC)technology,since the charge separation and utilization efficiency of a photoelectrode is critical to its PEC performance.Herein,we fabricate a F–Co_(3)O_(4)@Bi_(2)WO_(6) core–shell hetero-array photoanode by coupling Bi_(2)WO_(6) nanosheets with F–Co_(3)O_(4) nanowires using a simple solvothermal solution method.The three-dimensional hierarchical heterostructure has a homogeneous chemical interface,helping it to promote an S-scheme-based carrier transport kinetics and maintain excellent cycling stability.Charge density difference calculations verify the electron migration trend from F–Co_(3)O_(4) to Bi_(2)WO_(6) upon hybridization and the formation of an internal electric field in the heterojunction,consistent with the S-scheme mechanism,which is identified by in situ irradiation X-ray photoelectron spectroscopy and by ultraviolet photoelectron spectroscopy.The optimized F–Co_(3)O_(4)@Bi_(2)WO_(6)-2 photoelectrode achieves high carrier utilization efficiency and exhibits superior PEC degradation performance for various organic pollutants,including reactive brilliant blue KN-R,rhodamine B,sulfamethoxazole,and bisphenol A.This work not only reveals that F–Co_(3)O_(4)@Bi_(2)WO_(6)-2 is effective for PEC water remediation but also provides a strategy to enhance carrier transport kinetics by designing binary oxides.展开更多
The effective separation and migration of photogenerated charge carriers in bulk and on the surface of photocatalysts will significantly promote photocatalytic efficiency.However,the synchronous regulation of photocha...The effective separation and migration of photogenerated charge carriers in bulk and on the surface of photocatalysts will significantly promote photocatalytic efficiency.However,the synchronous regulation of photocharges on both counts is challenging.Herein,the simultaneous separation of bulk and surface photocharges is conducted to enhance photocatalytic activity by coupling the surface defects and lattice engineering of bismuth oxybromide.The depth-modulated Bi_(5)O_(7)Br ultrathin nanosheets with an abundance of bismuth in the crystal structure increased the internal electric field,which propelled the separation and migration of photocharges from bulk to the surface.Creation of oxygen vacancies(OVs)on the nanosheet surface forms local electric fields,which can stimulate the migration of charges to active sites on the catalyst surface.Therefore,the OV-assembled Bi_(5)O_(7)Br nanosheets demonstrated enhanced photocatalytic degradation efficiency under simulated solar-light illumination.This study proved the possibility of charge governing via electric field modulation based on an integrated strategy.展开更多
A specific type S-scheme photocatalyst CeO_(2)@N-GO/g-C_(3)N_(4)was successfully synthesized,resulting in a 2-mer-captobenzothiazole(MBT)degradation rate of 100%,which is more than twice that of g-C_(3)N_(4)and CeO_(2...A specific type S-scheme photocatalyst CeO_(2)@N-GO/g-C_(3)N_(4)was successfully synthesized,resulting in a 2-mer-captobenzothiazole(MBT)degradation rate of 100%,which is more than twice that of g-C_(3)N_(4)and CeO_(2).The improved degradation performance can be attributed to the introduction of N-graphene oxide(N-GO),which facilitates the electron transfer.Additionally,the unique Ce^(4+)→Ce^(3+)conversion property enhances the charge carrier utilization,and thereby the photocatalytic activity.Furthermore,theoretical calculations suggest the formation of an interfacial internal electric field(IEF)formed between CeO_(2)(the(200)and(311)planes)and g-C_(3)N_(4)(the(002)plane)to enhance the delocalization of the charge carriers.Moreover,various photo-electrochemical analyses are employed for the in-depth mechanism on MBT degradation and IEF-induced S-scheme over CeO_(2)@N-GO/g-C_(3)N_(4),where the differential charge proves the electron transfer path from CeO_(2)to g-C_(3)N_(4)that significantly prolongs its lifetime.The radical capture and electron spin resonance(ESR)results proved the existence of the active species of·OH,·O_(2)^(-),and h^(+)in the S-scheme photocatalytic system.展开更多
Photocatalysis has been expected to be a promising advanced oxidation process to endlessly convert exhaustless solar energy into storable,transportable,and usable chemical energy.As a kind of visible light-response se...Photocatalysis has been expected to be a promising advanced oxidation process to endlessly convert exhaustless solar energy into storable,transportable,and usable chemical energy.As a kind of visible light-response semiconductors,Bi-based semiconductors can be developed into step-scheme(S-scheme)heterojunction photocatalysts,consisting of a reductive photocatalyst(RP)and an oxidative photocatalyst(OP)with band edge bending.This review sums up the state-of-the-art progress in Bi-based S-scheme heterojunctions,as well as the in-/ex-situ experiments and theoretical calculations to uncover the unique heterostructure and charge transfer mechanism of Bi-based S-scheme heterojunctions in depth.We can find that Bi-based S-scheme heterojunction photocatalysts have advantages in impeding the recombination of photo-induced electron-hole pairs,expediting the charge transfer,broadening solar energy utilization,and maximizing the potential energy of photo-redox reaction sites.Additionally,the recently published work on the potential applications of Bi-based S-scheme heterojunctions is also summarized,including photocatalytic H_(2) production,CO_(2) reduction with water,pollutant degradation,H_(2)O_(2) production,and N_(2) photofixation for ammonia and urea production by comparing and discussing their photocatalytic efficiency.On the basis of research progress,the immediate challenges and future perspectives of Bi-based S-scheme heterojunction photocatalysts are critically debated.展开更多
Constructing heterojunction between two semiconductors with matched energy band structure is an effective modification method to obtain excellent photocatalysts.The experimental scheme adopts a simple solvent method t...Constructing heterojunction between two semiconductors with matched energy band structure is an effective modification method to obtain excellent photocatalysts.The experimental scheme adopts a simple solvent method to self-assemble nitrogen doped carbon dots(N-CDs)on the surface of sulfur doped carbon nitride(S-C_(3)N_(4))semiconductor throughπ-πconjugate interaction.Based on this,a novel 0D/2D S-scheme heterojunction N-CDs/S-C_(3)N_(4)hybrid was successfully prepared.The degradation kinetic constants of N-CDs/S-C_(3)N_(4)for rhodamine B(RhB)and p-nitrophenol(PNP)reached 0.23522 and 0.01342 min^(−1),repectively,which were 2.72 and 2.65 times that of S-C_(3)N_(4).The highest photocatalytic hydrogen evolution rate was observed under the simulated sunlight irradiation,which was 2.30 times that of S-C_(3)N_(4).The improvement of photocatalytic performance was mainly based on the formation of the S-scheme heterojunction between S-C_(3)N_(4)and N-CDs.The effects of internal electric field,π-πconjugate interaction and band bending promoted the photogenerated h^(+)and e^(−) with low redox ability to recombine and retained the beneficial h+and e−with strong redox ability,which contributed to the production of more active species of h^(+) and•O_(2)−,therefore the photocatalytic degradation and hydrogen evolution performance were significantly enhanced.展开更多
In this study,a facile alcoholysis method was developed to synthesize BiOCI_(x)Br_(1_x)nanoplates at room temperature and atmospheric pressure.In this route,strong acid or alkaline environment was absolutely avoided t...In this study,a facile alcoholysis method was developed to synthesize BiOCI_(x)Br_(1_x)nanoplates at room temperature and atmospheric pressure.In this route,strong acid or alkaline environment was absolutely avoided to realize the high exposure of{001}crystal facets.The regular changes in XRD peaks and cell parameters as a function of the Br content strongly declared that the obtained BiOCIxBrl_x products belonged to a group of solid solutions.The 2D nanosheets with in-plane wrinkles were clearly observed in TEM images.Interestingly,as the Br content increased,band gaps of BiOCI_(x)Br_(1_x)solid solutions gradually decreased.The photocatalytic degradation of RhB under simulated sunlight irradiation indicated that BiOCI0.sBr0.5 had the best photocatalytic activity.From the viewpoint of crystal chemistry,the photocatalytic activity of BiOCI_(x)Br_(1_x)solid solutions was closely related with the exposure amount of{001}facets,interlayer spacing of(001)plane and energy-level position of valence band.展开更多
基金supported by the National Natural Science Foundation of China(52200123)the Open Project of Key Laboratory of Green Chemical Engineering Process of Ministry of Education(GCP2022007)the Scientific Research and Innovation Team Program of Sichuan University of Science and Engineering(SUSE652A014)。
文摘Although the internal electric field(IEF)of photocatalysts is acknowledged as a potent driving force for photocharge separation,modulating the IEF intensity to achieve enhanced photocatalytic performances remains a challenge.Herein,cuprous sulfide nanosheets with different Cu vacancy concentration were employed to study IEF modulation and corresponding direct charge transfer.Among the samples,Cu_(1.8)S nanosheets possessed intensified IEF intensity compared with those of Cu_(2)S and Cu_(1.95)S nanosheets,suggesting that an enhanced IEF intensity could be achieved by introducing more Cu vacancies.This intensified IEF of Cu_(1.8)S nanosheets induced numerous photogenerated electrons to migrate to its surface,and the dissociative electrons were then captured by Cu vacancies,resulting in efficient charge separation spatially.In addition,the Cu vacancies on Cu_(1.8)S nanosheets accumulated electrons as active sites to lower the energy barrier of rate-determining step of CO_(2)photoreduction,leading to the selective conversion of CO_(2)to CO.Herein,the manipulation of IEF intensity through Cu vacancy concentration regulation of cuprous sulfide photocatalysts for efficient charge separation has been discussed,providing a scientific strategy to rationally improve photocata lytic performances for solar energy conversion.
文摘Constructing bismuth oxyhalide solid solutions with a single homogeneous phase have intrigued the research community;however,a deeper understanding of the intrinsic origin for improved bulk-charge separation is still unclear.Herein,a series of Bi_(24)O_(31)Cl_(x)Br_(10-x) solid solutions with the same structural characteristics were synthesized by crystal structure regulation.Combining density functional theory calculation,Kelvin probe force microscopy,and zeta potential testing results,an enhanced internal electric field(IEF)intensity between[Bi_(24)O_(31)]and[X]layers was achieved by changing halogen types and ratios.This greatly facilitated bulk-charge separation and transfer efficiency,which is significant for the degradation of phenolic organic pollutants.Owing to the enhanced IEF intensity,the charge carrier density of Bi_(24)O_(31)Cl_(4)Br_(6) was 33.1 and 4.7 times stronger than that of Bi_(24)O_(31)Cl_(10) and Bi_(24)O_(31)Br_(10),respectively.Therefore,Bi24O31Cl4Br6 had an optimal photoactivity for the degradation of bisphenol A,which was 6.21 and 2.71 times higher than those of Bi_(24)O_(31)Cl_(10) and Bi_(24)O_(31)Br_(10),respectively.Thus,this study revealed the intrinsic mechanism of the solid solution strategy for photocatalytic performance enhancement with respect to an IEF.
基金the National Natural Science Foundation of China(No.22138013).
文摘Heteroatom doping has emerged as a prevailing strategy to enhance the storage of sodium ions in carbon materials.However,the underlying mechanism governing the performance enhancement remains undisclosed.Herein,we fabricated N/S co-doped carbon beaded fibers(S-N-CBFs),which exhibited glorious rate performance and durableness in Na+storage,showcasing no obvious capacity decay even after 3500 cycles.Furthermore,when used as anodes in sodium-ion capacitors,the S-N-CBFs delivered exceptional results,boasting a high energy density of 225 Wh·kg^(-1),superior power output of 22500 W·kg^(-1),and outstanding cycling stability with a capacity attenuation of merely 0.014%per cycle after 4000 cycles at 2 A·g^(-1).Mechanistic investigations revealed that the incorporation of both pyridinic N and pyrrolic N into the carbon matrix of S-N-CBFs induced internal electric fields(IEFs),with the former IEF being stronger than the latter,in conjunction with the doped S atom.Density functional theory calculations further unveiled that the intensity of the IEF directly influenced the adsorption of Na+,thereby resulting in the exceptional performances of S-N-CBFs as sodium-ion storage materials.This work uncovers the pivotal role of IEF in regulating the electronic structure of carbon materials and enhancing their Na^(+)storage capabilities,providing valuable insights for the development of more advanced electrode materials.
基金the Shandong Province Natural Science Foundation (NO.ZR2020ME190)Cyrus Chung Ying Tang Foundation for the financial support
文摘Energy storage devices are the hub of a multi-energy complementary distributed energy system.Hydrated salts are the most suitable phase change material for energy storage devices,but subcooling is the main obstacle to their application.Nucleation requires a driving force so the use of nucleating agents alone does not reduce subcooling to a very low level.To address this issue,this paper first screened nucleating agents and then further reduced the subcooling of sodium acetate trihydrate in conjunction with stirring or direct current.The effects of rotor mass,rotational speed,direct current voltage,and electrode material on nucleation were analyzed.Finally,the stability of the composite phase change material in the presence of simultaneous stirring and energization was analyzed.The results showed that the addition of 1.5%in weight of disodium hydrogen phosphate dodecahydrate to sodium acetate trihydrate can reduce the subcooling to about 2.3℃.Continued addition of stirring or electricity can reduce the subcooling of sodium acetate trihydrate to within 0.5℃ or even eliminate it.The higher the momentum of the stirring,the better the improvement in subcooling,phase separation,and thermal conductivity.The higher the direct current voltage,the better the nucleation effect,but the electrode life will be lower.The silver electrode has the best nucleation effect.No new material was produced in the solution after 100 cycles in the presence of both stirring and direct current.The melting point of the phase change material was increased by 0.2℃ and the latent heat value decreased by 1.8%,still with good stability.The trace of deionized water should be added to the phase change material in subsequent studies to compensate for the consumption ofwaterby theanodicelution.
基金the National Nature Science Foundation of China(U20A20247 and 51922038).
文摘Stable potassium metal batteries(PMBs)are promising candidates for electrical energy storage due to their ability to reversibly store electrical energy at a low cost.However,dendritic growth and large volume changes hinder their practical application.Here,referring to the morphology and structure of a virus,a bionic virus-like-carbon microsphere(BVC)was designed as the anode host for a PMB.A BVC with a three-dimensional structure can not only control the electric field,which can suppress dendrite formation,but can also provide a larger space to accommodate the volume change during the cycle progress.The designed potassium(K)metal anode exhibits excellent cycle life and stability(during 1800 h of repeated plating/stripping of K at a current density of 0.1 mA cm−2,K-BVC can realize a very stable K metal anode with low voltage hysteresis).Stable cyclability and improved rate capability can be realized in a full cell using Prussian blue over 400 cycles.This research provides a new idea for the development of stable K metal anodes and may pave the way for the practical application of next-generation metal batteries.
基金This work was financially supported by the Liaoning Revital-ization Talents Program(No.1808013)the Shenyang National Laboratory for Materials Science.The authors thank Mr.Long Guan and Mr.Zhiyong Yang from Shenyang Dequan Instrument and Equipment Sales Co.,Ltd.for the Fluorescence microscope analysis and Mr.Jilong Gao from Shiyanjia Lab(www.shiyanjia.com)for the ss NMR analysis.
文摘Conjugated linear polymers are promising metal-free photocatalysts for visible-light-driven photocatalytic water disinfection,but it was still bottlenecked by the insufficient photogenerated charge separation and transport(CST)process.Herein,we obtained the highly crystalline imine-linked conjugated linear poly-mer(ODA-BPAH)with a greatly enhanced CST process.The highly crystalline ODA-BPAH exhibited excel-lent broad-spectrum water disinfection efficiency up to 99.99999%in 1 h,which is among the reported highest of state-of-the-art photocatalysts.The crystallinity of ODA-BPAH was regulated by simply turn-ing the solvent and the experiment results revealed that the ODA-BPAH with high crystallinity exhibited higher internal electric field strength and photocatalytic performance than that with low crystallinity,which indicates that higher crystallinity in linear conjugated polymers contributes to superior CST ef-ficiency as well as the generation of reactive oxygen species.This work highlights the impact of poly-mer crystallinity on the internal electric field and proves that linear poly-imine could be a new type of promising metal-free photocatalyst for water treatment.
基金the financial support by the National Natural Science Foundation of China as general projects(Grant Nos.51779068,52070066,52211530084,42277059,and 22006029)Tianjin Commission of Science and Technology as key technologies R&D projects(No.21YFSNSN00250)+1 种基金Doctoral Inno-vation Project of Hebei Province(CXZZBS2023031)the Royal Society/International Exchanges 2021 Cost Share/NSFC(Grant No.IEC\NSFC\211142).
文摘Heterojunction photocatalysts have shown considerable activities for organic pollutants degradation.However,the faint connection interface and inferior charge shift efficiency critically block the property of heterojunction photocatalysis.Herein,Bi_(2)O_(2)S/NiFe_(2)O_(4) nanosheets heterojunction with ultrastrong inter-face interaction and high internal electric field are designed by an in-situ growth method.Tentative and theoretical consequences prove that the interfacial interaction and internal electric field not only act as the electron flow bridge but also decrease the electrons shift energy obstacle,thus speeding up electrons transfer and achieving effective spatial electron-hole separation.Therefore,a large amount of·O_(2)^(-)and holes as active species were generated.Remarkably,Bi_(2)O_(2) S/NiFe_(2)O_(4) establishes a considerably boosted photocatalytic performance for tetracycline degradation(0.032 min^(-1)),which is about 14.2-fold and 7.8-fold of the pristine BOS and NFO,respectively.This work provides a promising motivation for modulating charge transfer by interface control and internal electric field to boost photocatalytic performance.
文摘Covalent organic frameworks(COFs)are promising materials for converting solar energy into green hydrogen.However,limited charge separation and transport in COFs impede their application in the photocatalytic hydrogen evolution reaction(HER).In this study,the intrinsically tunable internal bond electric field(IBEF)at the imine bonds of COFs was manipulated to cooperate with the internal molecular electric field(IMEF)induced by the donor-acceptor(D-A)structure for an efficient HER.The aligned orientation of IBEF and IMEF resulted in a remarkable H_(2) evolution rate of 57.3 mmol·g^(-1)·h^(-1)on TNCA,which was approximately 520 times higher than that of TCNA(0.11 mmol·g^(-1)·h^(-1))with the opposing electric field orientation.The superposition of the dual electric fields enables the IBEF to function as an accelerating field for electron transfer,kinetically facilitat-ing the migration of photogenerated electrons from D to A.Furthermore,theoretical calculations indicate that the inhomogeneous charge distribution at the C and N atoms in TNCA not only pro-vides a strong driving force for carrier transfer but also effectively hinders the return of free elec-trons to the valence band,improving the utilization of photoelectrons.This strategy of fabricating dual electric fields in COFs offers a novel approach to designing photocatalysts for clean energy synthesis.
基金National Natural Science Foundation of China(No.19672053)Special Funds for Doctoral Programs(No.96061305)
文摘In this article, distributions of internal stress and internal electric fields around a triple point of ferroelectric polycrystals generated by the spontaneous deformation and spontaneous polarization were investigated. It was found that when all three grains consist of a single domain, the internal stresses and the internal electric fields do not vanish. Though it may be determined according to the principle of energy, the spontaneous configuration will not be unique without involving other conditions due to the symmetry of the crystal structure.
基金Project supported by the National Natural Science Foundation of China （Grant Nos 10572155, 10172030 and 50232030）.
文摘We have performed the first-principles calculation to investigate the origins of ferroelectricities and different po- larization behaviours of superlattices BaTiO3/SrTiO3 and PbTiO3/SrTiO3. The density of state （DOS） and electronic charge profiles show that there are strong hybridizations between atoms Ti and O and between atoms Pb and O which play very important roles in producing the ferroelectricities of superlattices BaTiO3/SrTiO3 and PbTiO3/SrTiO3. Ow- ing to the decline of internal electric field in SrTiO3 （ST） layer, the tetragonality and polarizations of superlattices decrease with increasing the fraction of SrTiO3 in the superlattices. We find that the polarization of PbTiO3/SrTiO3 is largerthan that of BaTiO3/SrTiO3 at the same ratio of components, because the polarization mismatch between PbTiO3 and SrTiO3 is larger than that between BaTiO3 and SrTiO3. The polarization and tetragonality are en- hanced with respect to those of bulk tetragonal BaTiO3 in the superlattices BaTiO3/SrTiO3, while the polarization and tetragonality are reduced with respect to those of bulk tetragonal PbTiO3 in superlattices PbTiO3/SrTiO3.
基金supported by the National Natural Science Foundation of China(Grant Nos.U1862105,22108214,22050410267)Natural Science Basic Research Plan in Shaanxi Province of China(Grant Nos.2017JZ001,2018KJXX-008)+3 种基金Fundamental Research Funds for the Central Universities(Grant No.cxtd2017004)China Postdoctoral Science Foundation(Grant No.2021TQ0262)the Promotion Plan for Young People of Shaanxi Association for Science and Technology(20210605)K.C.Wong Education Foundation,Hong Kong,China。
文摘In this work,a novel NiP_(2)/g-C_(3)N_(4)heterojunction via homogeneous precipitation method assisted by thermal phosphorization reaction was designed and constructed,and the optimized sample showed the excellent photocatalytic H_(2)evolution activity under visible-light irradiation,which was nearly 112 times higher than that of pristine g-C_(3)N_(4)sample.Experimental characterizations and DFT calculations demonstrated that the NiP_(2)nanoparticles covered on the g-C_(3)N_(4)surface can form a built-in electric field at the interface to accelerate the transfer of photoexcited electrons from g-C_(3)N_(4)to NiP_(2),crucial for hindering the recombination of electron-hole pairs.Moreover,the energy barrier of hydrogen evolution reaction can also vastly reduce when combined NiP_(2)and g-C_(3)N_(4)to construct NiP_(2)/g-C_(3)N_(4)heterojunction.This work represents a method through combing experimental and theoretical tools to thoroughly investigate the mechanism of photocatalytic process.
文摘Carbon nitride(C_(3)N_(4))is promising for photocatalytic hydrogen production,but photogenerated electrons and holes in C_(3)N_(4)usually tend to exist as excitons due to intrinsic Coulomb interactions making its photocatalytic activity unsatisfactory.Herein,a well‐designed intramolecular C_(3)N_(4)‐based donor‐acceptor(D‐A)photocatalytic system was constructed to promote exciton dissociation.Due to its good chemical compatibility with melamine and appropriate sublimation property,2‐amino‐4,6‐dichloropyrimidine unit was chosen as the monomer to react with melamine to construct intramolecular D‐A system(CNCl_(x)).The hydrogen evolution rate of CNCl_(0.15)is 15.3 times higher than that of bulk C_(3)N_(4)under visible light irradiation,with apparent quantum efficiency of 13.6%at 420 nm.The enhanced activity is attributed to introduced electron‐withdrawing−Cl group as terminal group in the resulted CNCl_(x) samples,which can build internal electric field to promote the exciton dissociation into free electron and hole.In addition,lower work function value of CNCl_(x) samples indicates that internal electric field can help free electrons and holes transfer to the surface of CNCl_(x) samples for photocatalytic reaction.
基金supported by the National Natural Science Foundation of China(U1809214)the Natural Science Foundation of Zhejiang Province(LY20E080014,LTGN23E080001)the Science and Technology Project of Zhoushan(2022C41011)。
基金supported by the National Natural Science Foundation of China(21875026,21878031)the Program for Liaoning Excellent Talents in University(LR2014013)+2 种基金the Science and Technology Foundation of Liaoning Province(No.201602052)the Natural Science Foundation of Liaoning Province(No.20170520427)by the Liaoning Revitalization Talents Program(XLYC1802124).
文摘Devising a desirable nano-heterostructured photoelectrode based on the charge transfer kinetics mechanism is a pivotal strategy for implementing efficient photoelectrocatalytic(PEC)technology,since the charge separation and utilization efficiency of a photoelectrode is critical to its PEC performance.Herein,we fabricate a F–Co_(3)O_(4)@Bi_(2)WO_(6) core–shell hetero-array photoanode by coupling Bi_(2)WO_(6) nanosheets with F–Co_(3)O_(4) nanowires using a simple solvothermal solution method.The three-dimensional hierarchical heterostructure has a homogeneous chemical interface,helping it to promote an S-scheme-based carrier transport kinetics and maintain excellent cycling stability.Charge density difference calculations verify the electron migration trend from F–Co_(3)O_(4) to Bi_(2)WO_(6) upon hybridization and the formation of an internal electric field in the heterojunction,consistent with the S-scheme mechanism,which is identified by in situ irradiation X-ray photoelectron spectroscopy and by ultraviolet photoelectron spectroscopy.The optimized F–Co_(3)O_(4)@Bi_(2)WO_(6)-2 photoelectrode achieves high carrier utilization efficiency and exhibits superior PEC degradation performance for various organic pollutants,including reactive brilliant blue KN-R,rhodamine B,sulfamethoxazole,and bisphenol A.This work not only reveals that F–Co_(3)O_(4)@Bi_(2)WO_(6)-2 is effective for PEC water remediation but also provides a strategy to enhance carrier transport kinetics by designing binary oxides.
基金supported by the National Natural Science Foundation of China (22106072 and 42177356)the Fundamental Research Funds for the Central Universities (2022300301)+4 种基金the Natural Science Research Major Project of Jiangsu Higher Education Institutions of China (22KJA610003)the State Key Laboratory of Pollution Control and Resource Reuse Foundation (PCRRF21032)the Open Fund of Key Laboratory of Green Chemical Technology of Fujian Province University (WYKFGCT2022-3)China Postdoctoral Science Foundation (2022M721555)Jiangsu Funding Program for Excellent Postdoctoral Talent (2023ZB081)。
基金This work was supported by the National Natural Science Foundation of China(No.52002089)the innovation team of Xiangsi Lake Young Scholars of Guangxi Minzu University(No.2020RSCXSHQN06)the training program for thousands of backbone young teachers in Guangxi universities,and the undergraduate innovation and entrepreneurship project of Guangxi Minzu University(No.202110608002).
文摘The effective separation and migration of photogenerated charge carriers in bulk and on the surface of photocatalysts will significantly promote photocatalytic efficiency.However,the synchronous regulation of photocharges on both counts is challenging.Herein,the simultaneous separation of bulk and surface photocharges is conducted to enhance photocatalytic activity by coupling the surface defects and lattice engineering of bismuth oxybromide.The depth-modulated Bi_(5)O_(7)Br ultrathin nanosheets with an abundance of bismuth in the crystal structure increased the internal electric field,which propelled the separation and migration of photocharges from bulk to the surface.Creation of oxygen vacancies(OVs)on the nanosheet surface forms local electric fields,which can stimulate the migration of charges to active sites on the catalyst surface.Therefore,the OV-assembled Bi_(5)O_(7)Br nanosheets demonstrated enhanced photocatalytic degradation efficiency under simulated solar-light illumination.This study proved the possibility of charge governing via electric field modulation based on an integrated strategy.
基金supported by the National Natural Science Foundation of China(Nos.22208127,22108102)the Senior Talent Research Foundation of Jiangsu University(23JDG030)+1 种基金Hong Kong Scholar Program(XJ2020031)the RGC Postdoctoral Fellowship Scheme of Hong Kong.
文摘A specific type S-scheme photocatalyst CeO_(2)@N-GO/g-C_(3)N_(4)was successfully synthesized,resulting in a 2-mer-captobenzothiazole(MBT)degradation rate of 100%,which is more than twice that of g-C_(3)N_(4)and CeO_(2).The improved degradation performance can be attributed to the introduction of N-graphene oxide(N-GO),which facilitates the electron transfer.Additionally,the unique Ce^(4+)→Ce^(3+)conversion property enhances the charge carrier utilization,and thereby the photocatalytic activity.Furthermore,theoretical calculations suggest the formation of an interfacial internal electric field(IEF)formed between CeO_(2)(the(200)and(311)planes)and g-C_(3)N_(4)(the(002)plane)to enhance the delocalization of the charge carriers.Moreover,various photo-electrochemical analyses are employed for the in-depth mechanism on MBT degradation and IEF-induced S-scheme over CeO_(2)@N-GO/g-C_(3)N_(4),where the differential charge proves the electron transfer path from CeO_(2)to g-C_(3)N_(4)that significantly prolongs its lifetime.The radical capture and electron spin resonance(ESR)results proved the existence of the active species of·OH,·O_(2)^(-),and h^(+)in the S-scheme photocatalytic system.
基金jointly supported by the Fundamental Research Funds for Zhejiang Provincial Universities and Research Institutes(grant no.2022J002)Natural Science Foundation of Zhejiang Province(grant nos.LY20E080014 and TGN23E080003)+1 种基金the National Natural Science Foundation of China(grant no.51708504)the Science and Technology Project of Zhoushan(grant no.2022C41011).
文摘Photocatalysis has been expected to be a promising advanced oxidation process to endlessly convert exhaustless solar energy into storable,transportable,and usable chemical energy.As a kind of visible light-response semiconductors,Bi-based semiconductors can be developed into step-scheme(S-scheme)heterojunction photocatalysts,consisting of a reductive photocatalyst(RP)and an oxidative photocatalyst(OP)with band edge bending.This review sums up the state-of-the-art progress in Bi-based S-scheme heterojunctions,as well as the in-/ex-situ experiments and theoretical calculations to uncover the unique heterostructure and charge transfer mechanism of Bi-based S-scheme heterojunctions in depth.We can find that Bi-based S-scheme heterojunction photocatalysts have advantages in impeding the recombination of photo-induced electron-hole pairs,expediting the charge transfer,broadening solar energy utilization,and maximizing the potential energy of photo-redox reaction sites.Additionally,the recently published work on the potential applications of Bi-based S-scheme heterojunctions is also summarized,including photocatalytic H_(2) production,CO_(2) reduction with water,pollutant degradation,H_(2)O_(2) production,and N_(2) photofixation for ammonia and urea production by comparing and discussing their photocatalytic efficiency.On the basis of research progress,the immediate challenges and future perspectives of Bi-based S-scheme heterojunction photocatalysts are critically debated.
基金support from the National Natural Science Foundation of China (Nos. 51962023, 51772139)the Natural Science Foundation of Jiangxi Province, China (No. 20192ACBL21047, 20212BAB204045)+1 种基金the Key Laboratory of Jiangxi Province for Persistent Pollutants Control and Resources Recycle (Nanchang Hangkong University) (No. ES202002077)the 2019 Project of Liaoning Education Department (No. 2019LNJC20)
文摘Constructing heterojunction between two semiconductors with matched energy band structure is an effective modification method to obtain excellent photocatalysts.The experimental scheme adopts a simple solvent method to self-assemble nitrogen doped carbon dots(N-CDs)on the surface of sulfur doped carbon nitride(S-C_(3)N_(4))semiconductor throughπ-πconjugate interaction.Based on this,a novel 0D/2D S-scheme heterojunction N-CDs/S-C_(3)N_(4)hybrid was successfully prepared.The degradation kinetic constants of N-CDs/S-C_(3)N_(4)for rhodamine B(RhB)and p-nitrophenol(PNP)reached 0.23522 and 0.01342 min^(−1),repectively,which were 2.72 and 2.65 times that of S-C_(3)N_(4).The highest photocatalytic hydrogen evolution rate was observed under the simulated sunlight irradiation,which was 2.30 times that of S-C_(3)N_(4).The improvement of photocatalytic performance was mainly based on the formation of the S-scheme heterojunction between S-C_(3)N_(4)and N-CDs.The effects of internal electric field,π-πconjugate interaction and band bending promoted the photogenerated h^(+)and e^(−) with low redox ability to recombine and retained the beneficial h+and e−with strong redox ability,which contributed to the production of more active species of h^(+) and•O_(2)−,therefore the photocatalytic degradation and hydrogen evolution performance were significantly enhanced.
文摘In this study,a facile alcoholysis method was developed to synthesize BiOCI_(x)Br_(1_x)nanoplates at room temperature and atmospheric pressure.In this route,strong acid or alkaline environment was absolutely avoided to realize the high exposure of{001}crystal facets.The regular changes in XRD peaks and cell parameters as a function of the Br content strongly declared that the obtained BiOCIxBrl_x products belonged to a group of solid solutions.The 2D nanosheets with in-plane wrinkles were clearly observed in TEM images.Interestingly,as the Br content increased,band gaps of BiOCI_(x)Br_(1_x)solid solutions gradually decreased.The photocatalytic degradation of RhB under simulated sunlight irradiation indicated that BiOCI0.sBr0.5 had the best photocatalytic activity.From the viewpoint of crystal chemistry,the photocatalytic activity of BiOCI_(x)Br_(1_x)solid solutions was closely related with the exposure amount of{001}facets,interlayer spacing of(001)plane and energy-level position of valence band.
