This study explores a symmetric configuration approach in anion exchange membrane(AEM)water electrolysis,focusing on overcoming adaptability challenges in dynamic conditions.Here,a rapid and mild synthesis technique f...This study explores a symmetric configuration approach in anion exchange membrane(AEM)water electrolysis,focusing on overcoming adaptability challenges in dynamic conditions.Here,a rapid and mild synthesis technique for fabricating fibrous membrane-type catalyst electrodes is developed.Our method leverages the contrasting oxidation states between the sulfur-doped NiFe(OH)2 shell and the metallic Ni core,as revealed by electron energy loss spectroscopy.Theoretical evaluations confirm that the S–NiFe(OH)_(2) active sites optimize free energy for alkaline water electrolysis intermediates.This technique bypasses traditional energy-intensive processes,achieving superior bifunctional activity beyond current benchmarks.The symmetric AEM water electrolyzer demonstrates a current density of 2 A cm^(-2) at 1.78 V at 60℃ in 1 M KOH electrolyte and also sustains ampere-scale water electrolysis below 2.0 V for 140 h even in ambient conditions.These results highlight the system's operational flexibility and structural stability,marking a significant advance-ment in AEM water electrolysis technology.展开更多
Ni-based porous electrocatalysts have been widely used in the hydrogen evolution reaction(HER)in alkaline water electrolysis,and the catalysts are produced by selective leaching of Al from Ni-Al alloys.It is well know...Ni-based porous electrocatalysts have been widely used in the hydrogen evolution reaction(HER)in alkaline water electrolysis,and the catalysts are produced by selective leaching of Al from Ni-Al alloys.It is well known that chemical leaching of Ni-Al intermetallic compound(IMC)generates a high surface area in Ni(OH)_(2).However,the Ni(OH)_(2) produced by leaching the Ni-Al intermetallic compound retards the hydrogen evolution reaction,which is attributed to its weak hydrogen adsorption energy.In this study,we controlled the chemical state of Ni using plasma vapor deposition(PVD)followed by heat treatment,selective Al leaching,and electrochemical reduction.X-ray diffraction(XRD),scanning microscopy(SEM),transmission electron microscopy(TEM),and energy-dispersive X-ray spectroscopy(EDS)were used to confirm the phase evolution of the electrocatalysts during fabrication.We reveal that the heat-treated Ni-Al alloy with a thick Ni2Al3surface layer underwent selective Al leaching and produced biphasic interfaces comprising Ni(OH)_(2) and NiAl IMCs at the edges of the grains in the outermost surface layer.Coupled oxidation of the interfacing NiAl IMCs facilitated the partial reduction of Ni(OH)_(2) to Ni(OH)_(2)/Ni in the grains during electrochemical reduction,as confirmed by X-ray photoelectron spectroscopy(XPS).An electrocatalyst containing partially reduced Ni(OH)_(2)/Ni exhibited an overpotential of 54 mV at 10 mA/cm^(2) in a half-cell measurement,and a cell voltage of 1.675 V at 0.4 A/cm2for single-cell operation.A combined experimental and theoretical study(density functional theory calculations)revealed that the superior HER activity was attributed to the presence of partially reduced metallic Ni with various defects and residual Al,which facilitated water adsorption,dissociation,and finally hydrogen evolution.展开更多
This paper presents the investigation of energy and cost saving of microgeneration systems which consist of conventional, load sharing, renewable energy and hybrid-renewable energy systems application featuring single...This paper presents the investigation of energy and cost saving of microgeneration systems which consist of conventional, load sharing, renewable energy and hybrid-renewable energy systems application featuring single detached house and office buildings by implementing spreadsheet modeling. Microsoft excel is employed as the spreadsheet application in this study. The system performance of each case is calculated under typical weather of ottawa, canada. These cases are calculated and analyzed in terms of thermal/cooling load （building demand） and natural gas/electricity consumption （energy supply） as well as the financial part by involving several parameters which are initial cost, annual energy consumption cost, annual operational and maintenance cost, inflation rate, and return on investment. Moreover, a house and an office have the same geometry of 200 mE. Total of seven cases modeling are developed; Case-1- a house with boiler and chiller, Case-2- an office with boiler and chiller, Case-3-a simple sum of Case l and Case 2, Case-4- a load-sharing model, Case-5- a load-sharing with GSHP （ground source heat pump）, Case-6- a load-sharing with ground source heat pump-fuel cell hybrid system （FC-GSHP）and Case-7- a load-sharing with GSHP--photovoltaic hybrid system （PVT-GSHP）. As the results, it will be observed the efficiency of the load-sharing, renewable energy, hybrid-renewable energy implementation comparing to the conventional system.展开更多
To demonstrate flexible and tandem device applications,a low-temperature Cu_(2)ZnSnSe_(4)(CZTSe)deposition process,combined with efficient alkali doping,was developed.First,high-quality CZTSe films were grown at 480℃...To demonstrate flexible and tandem device applications,a low-temperature Cu_(2)ZnSnSe_(4)(CZTSe)deposition process,combined with efficient alkali doping,was developed.First,high-quality CZTSe films were grown at 480℃by a single co-evaporation,which is applicable to polyimide(PI)substrate.Because of the alkali-free substrate,Na and K alkali doping were systematically studied and optimized to precisely control the alkali distribution in CZTSe.The bulk defect density was significantly reduced by suppression of deep acceptor states after the(NaF+KF)PDTs.Through the low-temperature deposition with(NaF+KF)PDTs,the CZTSe device on glass yields the best efficiency of 8.1%with an improved Voc deficit of 646 mV.The developed deposition technologies have been applied to PI.For the first time,we report the highest efficiency of 6.92%for flexible CZTSe solar cells on PI.Additionally,CZTSe devices were utilized as bottom cells to fabricate four-terminal CZTSe/perovskite tandem cells because of a low bandgap of CZTSe(~1.0 eV)so that the tandem cell yielded an efficiency of 20%.The obtained results show that CZTSe solar cells prepared by a low-temperature process with in-situ alkali doping can be utilized for flexible thin-film solar cells as well as tandem device applications.展开更多
The study on the removal of NOx from simulated flue gas has been carded out in a lab-scale bubbling reactor using acidic solutions of sodium chlorite. Experiments were performed at various pH values and inlet NO conce...The study on the removal of NOx from simulated flue gas has been carded out in a lab-scale bubbling reactor using acidic solutions of sodium chlorite. Experiments were performed at various pH values and inlet NO concentrations in the absence or presence of SO2 gas at 45℃. The effect of SO2 on NO oxidation and NO2 absorption was critically examined. The oxidative ability of sodium chlorite was investigated at different pH values and it was found to be a better oxidant at a pH less than 4. In acidic medium, sodium chlorite decomposed into C102 gas, which is believed to participate in NO oxidation as well as in NO2 absorption. A plausible NOx removal mechanism using acidic sodium chlorite solution has been postulated. A maximum NOx removal efficiency of about 81% has been achieved.展开更多
The carbon dioxide （CO2） removal efficiency, reaction rate, and CO2 loading into aqueous blended monoethanolamine （MEA） ＋ 2-amino-2-methyl-l-propanol （AMP） solutions to enhance absorption characteristics of MEA...The carbon dioxide （CO2） removal efficiency, reaction rate, and CO2 loading into aqueous blended monoethanolamine （MEA） ＋ 2-amino-2-methyl-l-propanol （AMP） solutions to enhance absorption characteristics of MEA and AMP were carried out by the absorption/regeneration process. As a result, compared to aqueous MEA and AMP solutions, aqueous blended MEA ＋ AMP solutions have a higher CO2 loading than MEA and a higher reaction rate than AMP. The CO2 loading of rich amine of aqueous 18 wt.% MEA ＋ 12 wt.% AMP solution was 0.62 mol CO2/mol amine, which is 51.2% more than 30 wt.% MEA （0.41 mol CO2/mol amine）. Consequently, blending MEA and AMP could be an effective way to design considering economical efficiency and used to operate absorber for a long time.展开更多
The objective of the present study is to characterize the production of hydrogen with a sorptionenhanced steam-methane reaction process using Ca(OH)2 as the CO2 adsorbent. Theoretical equilibrium compositions at diffe...The objective of the present study is to characterize the production of hydrogen with a sorptionenhanced steam-methane reaction process using Ca(OH)2 as the CO2 adsorbent. Theoretical equilibrium compositions at different operation conditions were calculated using an iterative method. It was found that with Ca(OH)2 as the CO2 sorbent, the concentration of CO2 adsorption was reduced in the product stream, that gave rise to higher methane conversion and higher H2 concentration. An experimental setup was built to test the theoretical calculation. The effects of sorbents and the particle size of Ca(OH)2 on the concentration of CO2 and H2 were investigated in detail. Results showed that the reactor packed with catalyst and Ca(OH)2 particles produced H2 concentration of 94%. It was nearly 96% of the theoretical equilibrium limit, much higher than H2 equilibrium concentration of 67.5% without CO2 sorption under the same conditions of 500℃, 0.2 MPa pressure and a steam-to-methane ratio 6. In addition, the residual mole fraction of CO2 was less than 0.001.展开更多
Attempts have been made to generate euchlorine gas by chlorate-chloride process and to utilize it further to clean up SO2 and NOx from the flue gas in a lab scale bubbling reactor. Preliminary experiments were carded ...Attempts have been made to generate euchlorine gas by chlorate-chloride process and to utilize it further to clean up SO2 and NOx from the flue gas in a lab scale bubbling reactor. Preliminary experiments were carded out to determine the gas and liquid phase mass transfer coefficients and their correlation equations have been established. Simultaneous removal of SO2 and NOx from the simulated flue gas using aqueous euchlorine scrubbing solution has been investigated. Euchlorine oxidized NO into NO2 completely and the later subsequently absorbed into the scrubbing solution in the form of nitrate. SO2 removal efficiency around 100% and NOx removal efficiency around 72% were achieved under optimal conditions. Mass balance has been confirmed by analyzing the sulfate, nitrate, euchlorine and chloride ion using ion chromatograph/auto-titrator and comparing it with their corresponding calculated values.展开更多
Pt-Ni alloy nanocrystals with Pt-enriched shells were prepared by selective etching of surface Ni using sulfuric acid and hydroquinone.The changes in the electronic and geometric structure of the alloy nanoparticles a...Pt-Ni alloy nanocrystals with Pt-enriched shells were prepared by selective etching of surface Ni using sulfuric acid and hydroquinone.The changes in the electronic and geometric structure of the alloy nanoparticles at the surface were elucidated from the electrochemical surface area,the potential of zero total charge(PZTC),and relative surface roughness,which were determined from CO-and CO_(2)-displacement experiments before and after 3000 potential cycles under oxygen reduction reaction conditions.While the highest activity and durability were achieved in hydroquinone-treated Pt–Ni,sulfuric acidtreated one showed the lower activity and durability despite its higher surface Pt concentration and alloying level.Both PZTC and QCO_(2)/QCO ratio(desorption charge of reductively adsorbed CO_(2) normalized by COad-stripping charge)depend on surface roughness.In particular,QCO_(2)/QCO ratio change better reflects the roughness on an atomic scale,and PZTC is also affected by the electronic modification of Pt atoms in surface layers.In this study,a comparative study is presented to find a relationship between surface structure and electrochemical properties,which reveals that surface roughness plays a critical role to improve the electrochemical performance of Pt-Ni alloy catalysts with Pt-rich surfaces.展开更多
The chemical looping gasification uses an oxygen carrier for solid fuel gasification by supplying insufficient lattice oxygen. The effect of gasifying medium on the coal chemical looping gasification with Ca SO4 as ox...The chemical looping gasification uses an oxygen carrier for solid fuel gasification by supplying insufficient lattice oxygen. The effect of gasifying medium on the coal chemical looping gasification with Ca SO4 as oxygen carrier is investigated in this paper. The thermodynamical analysis indicates that the addition of steam and CO2 into the system can reduce the reaction temperature, at which the concentration of syngas reaches its maximum value.Experimental result in thermogravimetric analyzer and a fixed-bed reactor shows that the mixture sample goes through three stages, drying stage, pyrolysis stage and chemical looping gasification stage, with the temperature for three different gaseous media. The peak fitting and isoconversional methods are used to determine the reaction mechanism of the complex reactions in the chemical looping gasification process. It demonstrates that the gasifying medium(steam or CO2) boosts the chemical looping process by reducing the activation energy in the overall reaction and gasification reactions of coal char. However, the mechanism using steam as the gasifying medium differs from that using CO2. With steam as the gasifying medium, parallel reactions occur in the beginning stage, followed by a limiting stage shifting from a kinetic to a diffusion regime. It is opposite to the reaction mechanism with CO2 as the gasifying medium.展开更多
The influence of the dehydration by metal oxides on the synthesis of dimethyl carbonate （DMC） via oxidative carbonylation of methanol was studied. A Cu/Y-zeolite catalyst was prepared by the ion exchange method from...The influence of the dehydration by metal oxides on the synthesis of dimethyl carbonate （DMC） via oxidative carbonylation of methanol was studied. A Cu/Y-zeolite catalyst was prepared by the ion exchange method from CuCl2.2H2O and the commercial NH4-form of the Y type zeolite, The catalyst was characterized by X-ray fluorescence （XRF）, N2 adsorption （BET method）, X-ray diffraction （XRD）, and temperature-programmed de- sorption of ammonia （NH3-TPD） to evaluate its Cu and Cl content, surface area, structure, and acidity. Reaction tests were carried out using an autoclave （batch reactor） for 18 h at 403 K and 5.5 MPa （2CH3OH ＋ 1/2O2 ＋ CO （CH3O）2CO ＋ H2O）. The influence of various dehydrating agents （ZnO, MgO, and CaO） was examined with the aim of increasing the methanol conversion （XMeOH, MeOH conversion）. The MeOH conversion increased upon addition of metal oxides in the order CaO 〉〉 MgO 〉 ZnO, with the DMC selectivity （SDMC） following the order MgO 〉 CaO 〉 ZnO. The catalysts and dehydrating agents were characterized before and after the oxidative carbonylation of methanol by thermogravimetric and differential thermogravimetric （TG/DTG）, and XRD to con- firm that the dehydration reaction occurred via the metal oxide （MO ＋ H2O →M（OH）2）. The MeOH conversion increased from 8.7% to 14.6% and DMC selectivity increased from 39.0% to 53.1%, when using the dehydrating azent CaO.展开更多
Alcohol-assisted low-temperature methanol synthesis was conducted over Cu/ZnO;catalysts while varying the copper content（X）. Unlike conventional methanol synthesis, ethanol acted as both solvent and reaction interme...Alcohol-assisted low-temperature methanol synthesis was conducted over Cu/ZnO;catalysts while varying the copper content（X）. Unlike conventional methanol synthesis, ethanol acted as both solvent and reaction intermediate in this reaction, creating a different reaction pathway. The formation of crystalline phases and characteristic morphology of the co-precipitated precursors during the co-precipitation step were important factors in obtaining an efficient Cu/ZnO catalyst with a high dispersion of metallic copper,which is one of the main active sites for methanol synthesis. The acidic properties of the Cu/ZnO catalyst were also revealed as important factors, since alcohol esterification is considered the rate-limiting step in alcohol-assisted low-temperature methanol synthesis. As a consequence, bifunctionality of the Cu/ZnO catalyst such as metallic copper and acidic properties was required for this reaction. In this respect, the copper content（X） strongly affected the catalytic activity of the Cu/ZnO;catalysts, and accordingly, the Cu/ZnO;.5 catalyst with a high copper dispersion and sufficient acid sites exhibited the best catalytic performance in this reaction.展开更多
A precipitation system developed continuously along the western coastline of the Korean Peninsula and created considerable precipitation both along the coast and inland on 26 July 2011. In this study, the causes for t...A precipitation system developed continuously along the western coastline of the Korean Peninsula and created considerable precipitation both along the coast and inland on 26 July 2011. In this study, the causes for this nearshore convective system are investigated from observations and the results of model experiments. Three-dimensional radar fields clearly show that a change of wind at the surface border played an important role in the development of the nearshore convection system. The simulation results, which are very similar to the observations, show that the surface border generated and maintained the convergence zone. The roughness change enhanced the convergence, and the interaction between the deepening cold pool and downward flow maintained the convergence zone. The surface mechanical discontinuity affected by the roughness change between sea and land formed the convergence (gradient of wind stress), which induced momentum transfer to the upper layer. The cold pool created a steep gradient of potential temperature and provided the reason for the propagated convergence zone with the downward flow. The maximum value of the surface change factor, which comprises the influencing factors for the long-lasting convective system, reflects the enhancement of the system at the coast.展开更多
Carbon deposition via coke formation is one of the critical problems causing catalyst deactivation during the reforming of hydrocarbons. An effort was made to regenerate the catalyst （Ni/γ-alumina） by oxidation met...Carbon deposition via coke formation is one of the critical problems causing catalyst deactivation during the reforming of hydrocarbons. An effort was made to regenerate the catalyst （Ni/γ-alumina） by oxidation methods. Two approaches were carded out for the regeneration of the deactivated catalyst. The first one involves the plasma treatment of the deactivated catalyst in the presence of dry air over a temperature range of 300-500℃, while the second one only the thermal treatment in the same temperature range. The performance of the regenerated catalyst was evaluated in terms of C4H10 and CO2 conversions and the physicochemical characteristics were examined using a surface area analyzer, an elemental analyzer, scanning electron microscopy （SEM） and transmission electron microscopy （TEM）. It was observed that the carbon deposit （coke） on the catalyst was about 9.89 wt% after reforming C4H10 for 5 h at 540℃. The simple thermal treatment at 400 ℃ reduced carbon content to 6.59 wt% whereas it was decreased to 3.25 wt% by the plasma and heat combination. The specific surface area was fully restored to the original state by the plasma-assisted regeneration at 500℃. As far as the catalytic activity is concerned, the fresh and regenerated catalysts exhibited similar C4H10 and CO2 conversion efficiencies.展开更多
Ammonia (NH_(3)) plays a key role in the agricultural fertilizer and commodity chemical industries and is useful for exploring hydrogen storage carriers.The electrochemical nitrogen reduction reaction (NRR) is receivi...Ammonia (NH_(3)) plays a key role in the agricultural fertilizer and commodity chemical industries and is useful for exploring hydrogen storage carriers.The electrochemical nitrogen reduction reaction (NRR) is receiving attention as an environmentally sustainable NH_(3) synthesis replacement for the traditional Haber–Bosch process owing to its near ambient reaction conditions (<100℃ and 1 atm).However,its NH_(3) yield and faradaic efficiency are extremely low because of the sluggish kinetics of N≡N bond dissociation and the hindrance from competitive hydrogen evolution.To overcome these challenges,we herein introduce a dual-functionalized ionic liquid (1-(4-hydroxybutyl)-3-methylimidazolium hydroxide[HOBIM]OH) for a highly dispersed ruthenium oxide electrocatalyst to achieve a biased NRR.The observed uniform distribution of RuO_(2) on the carbon fiber and increase in the surface area for N_(2) adsorption by limiting proton access can be attributed to the presence of imidazolium ions.Moreover,extensive N_(2) adsorption contributes to enhanced NRR selectivity with an NH_(3) yield of 3.0×10^(-10)mol cm^(-2)s^(-1)(91.8μg h^(-1)mg^(-1)) and a faradaic efficiency of 2.2%at-0.20 V_(RHE).We expect our observations to provide new insights into the design of effective electrode structures for electrochemical NH;synthesis.展开更多
In sludge treatment, drying sludge using typical technology with high water content to a water content of approximately 10% is always difficult because of adhesive characteristics of sludge in drying. Many methods hav...In sludge treatment, drying sludge using typical technology with high water content to a water content of approximately 10% is always difficult because of adhesive characteristics of sludge in drying. Many methods have been applied, including direct and indirect heat drying, but these approaches of reducing water content to below 40% after drying are very inefficient in energy utilization of drying sludge. In this study, fry-drying technology with a high heat transfer coefficient of approximately 500 W/m2·°C was used to dry swine excreta, sewage and industrial sludge. Also waste oil was used in the fry-drying process, and because the oil’s boiling point is between 240°C and 340°C and the specific heat is approximately 60% of that of water. In the fry-drying system, the sludge is input by molding it into a designated form after heating the waste oil at temperatures between 130°C and 150°C. At these temperatures, the heated oil rapidly evaporates the water contained in the sludge, leaving the oil itself. After approximately 8 - 10 min, the water content of the sludge was less than 10%, and its heating value surpassed 20,000 kJ/kg. Indeed, this makes the organic sludge appropriate for use as a solid fuel. The dried swine excreta, sewage and industrial sludge can be used in an incinerator like low-rank coal or solid fuel.展开更多
Characteristics of sulfur dioxide emission from coal and petroleum coke combustion were examined in a lab scale circulating fluidized bed (CFB) combustor. The rate constant of the first order rate expression for the a...Characteristics of sulfur dioxide emission from coal and petroleum coke combustion were examined in a lab scale circulating fluidized bed (CFB) combustor. The rate constant of the first order rate expression for the absorption SO2 on the CaO surface was similar regardless of the origin of the limestone, the particle size and the initial SO2 concentration. However, the total SO2 absorption capacity was different depending on the origin of the limestone. The breakability of the particle which provides new surface for the reaction seems to play a major role in the absorption characteristics.展开更多
Heating,ventilation,and air conditioning(HVAC)systems account for one-third of the total energy consumption in office buildings.The use of airflow measurements to control the operation of HVAC systems can reduce energ...Heating,ventilation,and air conditioning(HVAC)systems account for one-third of the total energy consumption in office buildings.The use of airflow measurements to control the operation of HVAC systems can reduce energy consumption;thus,a sensor capable of monitoring airflow in a duct system is critical.Triboelectric nanogenerators(TENGs)can be utilized as self-powered sensors in airflow-driven TENGs(ATENGs)as self-powered sensors.By employing ferroelectric materials and surface modifications,the surface charges of TENGs can be increased.In this study,fibrous-mat TENGs were prepared using ferroelectric materials consisting of poly(vinylidene fluoride-co-trifluoroethylene)(PVDF-TrFE)and polyamide 11(nylon-11).And these materials were subsequently investigated.Poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate)was added to PVDF-TrFE to enhance the ferroelectric crystalline phase.X-ray diffraction analysis revealed that this incorporation affects theβphase.In addition,the surface of nylon-11 was modified using the electrospray technique for post-treatment,thereby improving the interfacial adhesion between the fibers.These materials were then utilized in fibrous-mat ATENGs(FM-ATENGs)to demonstrate their practical application.The FM-ATENGs can be effectively used in an Arduino airflowcheck sensor,showcasing their potential for application in HVAC systems,to enhance airflow control and energy efficiency.展开更多
Traditional iridium (Ir) oxide catalysts have faced significant limitations in water electrolysis, particularly under acidic conditions where instability and degradation severely restrict the efficiency of the oxygen ...Traditional iridium (Ir) oxide catalysts have faced significant limitations in water electrolysis, particularly under acidic conditions where instability and degradation severely restrict the efficiency of the oxygen evolution reaction (OER) and hydrogen evolution reaction (HER). To overcome these challenges, this study successfully synthesized highly dispersed IrPtPdNi alloy nanoparticles on a graphene oxide support using a vertically moving reactor, demonstrating exceptional performance in water electrolysis. These nanoparticles, synthesized via a fast-moving bed pyrolysis method, combine iridium, platinum, palladium, and nickel. They exhibit lower overpotentials in OER and comparable performance in HER to commercial catalysts, while also offering enhanced stability. These results surpass the limitations of traditional catalysts, marking significant progress toward more efficient and sustainable hydrogen production technologies. This advancement is expected to contribute significantly to the development of sustainable energy systems by innovatively enhancing the performance of catalysts in the electrochemical water-splitting process.展开更多
The rapid growth of miniaturized electronics has led to an urgent demand for microscale energy storage devices(MESDs)to sustainably power the micro electronic devices.However,most MESDs reported to date have suffered ...The rapid growth of miniaturized electronics has led to an urgent demand for microscale energy storage devices(MESDs)to sustainably power the micro electronic devices.However,most MESDs reported to date have suffered from the limited energy densities and shape versatility compared to conventional large-scale counterparts because of the architectural constraints inherent in microfabrication-based cell manufacturing and cell dimension/structure.This review addresses the cell architecture design for MESDs that can achieve both miniaturization and high energy density.We provide a comprehensive overview of five types of cell architectures of MESDs and their fabrication techniques.In addition,to enable practical applications of MESDs,several cell design approaches are presented with the aim of minimizing the inactive parts of the cell and maximizing the performance metrics of MESDs.Finally,we discuss development direction and outlook of MESDs with a focus on materials chemistry,energy-dense electrochemical systems,and cell performance normalization,which will help to expand their applications and manufacturing scalability.展开更多
基金This research was supported by the“Regional Innovation Strategy(RIS)”through the National Research Foundation of Korea(NRF)funded by the Ministry of Education(MOE)(2021RIS-002)This work was supported by an NRF grant funded by the Ministry of Science,ICT,and Future Planning(No.NRF-2018R1C1B6005009,NRF-2021R1C1C1012676,and 2009-0082580).
文摘This study explores a symmetric configuration approach in anion exchange membrane(AEM)water electrolysis,focusing on overcoming adaptability challenges in dynamic conditions.Here,a rapid and mild synthesis technique for fabricating fibrous membrane-type catalyst electrodes is developed.Our method leverages the contrasting oxidation states between the sulfur-doped NiFe(OH)2 shell and the metallic Ni core,as revealed by electron energy loss spectroscopy.Theoretical evaluations confirm that the S–NiFe(OH)_(2) active sites optimize free energy for alkaline water electrolysis intermediates.This technique bypasses traditional energy-intensive processes,achieving superior bifunctional activity beyond current benchmarks.The symmetric AEM water electrolyzer demonstrates a current density of 2 A cm^(-2) at 1.78 V at 60℃ in 1 M KOH electrolyte and also sustains ampere-scale water electrolysis below 2.0 V for 140 h even in ambient conditions.These results highlight the system's operational flexibility and structural stability,marking a significant advance-ment in AEM water electrolysis technology.
基金supported by a Korea Evaluation Institute of Industrial Technology(KEIT)grant funded by the Korean government(MOTIE)(No.20022449)Commercialization Promotion Agency for R&D Outcomes(COMPA)grant funded by the Korean government(MSIT)(No.2021E100)+1 种基金supported by the Korea Electric Power Corporation(KEPCO),Open R&D(R22X004)the National Institute of Supercomputing and Network/Korea Institute of Science and Technology Information,which provided supercomputing resources,including technical support(KSC-2021-CRE-0568)。
文摘Ni-based porous electrocatalysts have been widely used in the hydrogen evolution reaction(HER)in alkaline water electrolysis,and the catalysts are produced by selective leaching of Al from Ni-Al alloys.It is well known that chemical leaching of Ni-Al intermetallic compound(IMC)generates a high surface area in Ni(OH)_(2).However,the Ni(OH)_(2) produced by leaching the Ni-Al intermetallic compound retards the hydrogen evolution reaction,which is attributed to its weak hydrogen adsorption energy.In this study,we controlled the chemical state of Ni using plasma vapor deposition(PVD)followed by heat treatment,selective Al leaching,and electrochemical reduction.X-ray diffraction(XRD),scanning microscopy(SEM),transmission electron microscopy(TEM),and energy-dispersive X-ray spectroscopy(EDS)were used to confirm the phase evolution of the electrocatalysts during fabrication.We reveal that the heat-treated Ni-Al alloy with a thick Ni2Al3surface layer underwent selective Al leaching and produced biphasic interfaces comprising Ni(OH)_(2) and NiAl IMCs at the edges of the grains in the outermost surface layer.Coupled oxidation of the interfacing NiAl IMCs facilitated the partial reduction of Ni(OH)_(2) to Ni(OH)_(2)/Ni in the grains during electrochemical reduction,as confirmed by X-ray photoelectron spectroscopy(XPS).An electrocatalyst containing partially reduced Ni(OH)_(2)/Ni exhibited an overpotential of 54 mV at 10 mA/cm^(2) in a half-cell measurement,and a cell voltage of 1.675 V at 0.4 A/cm2for single-cell operation.A combined experimental and theoretical study(density functional theory calculations)revealed that the superior HER activity was attributed to the presence of partially reduced metallic Ni with various defects and residual Al,which facilitated water adsorption,dissociation,and finally hydrogen evolution.
文摘This paper presents the investigation of energy and cost saving of microgeneration systems which consist of conventional, load sharing, renewable energy and hybrid-renewable energy systems application featuring single detached house and office buildings by implementing spreadsheet modeling. Microsoft excel is employed as the spreadsheet application in this study. The system performance of each case is calculated under typical weather of ottawa, canada. These cases are calculated and analyzed in terms of thermal/cooling load （building demand） and natural gas/electricity consumption （energy supply） as well as the financial part by involving several parameters which are initial cost, annual energy consumption cost, annual operational and maintenance cost, inflation rate, and return on investment. Moreover, a house and an office have the same geometry of 200 mE. Total of seven cases modeling are developed; Case-1- a house with boiler and chiller, Case-2- an office with boiler and chiller, Case-3-a simple sum of Case l and Case 2, Case-4- a load-sharing model, Case-5- a load-sharing with GSHP （ground source heat pump）, Case-6- a load-sharing with ground source heat pump-fuel cell hybrid system （FC-GSHP）and Case-7- a load-sharing with GSHP--photovoltaic hybrid system （PVT-GSHP）. As the results, it will be observed the efficiency of the load-sharing, renewable energy, hybrid-renewable energy implementation comparing to the conventional system.
基金financially supported by the Korea Institute of Energy Research(KIER)(grant no.C3-2401,2402,2403)the National Research Foundation(grant no.2022M3J1A1063019)funded by the Ministry of Science and ICT
文摘To demonstrate flexible and tandem device applications,a low-temperature Cu_(2)ZnSnSe_(4)(CZTSe)deposition process,combined with efficient alkali doping,was developed.First,high-quality CZTSe films were grown at 480℃by a single co-evaporation,which is applicable to polyimide(PI)substrate.Because of the alkali-free substrate,Na and K alkali doping were systematically studied and optimized to precisely control the alkali distribution in CZTSe.The bulk defect density was significantly reduced by suppression of deep acceptor states after the(NaF+KF)PDTs.Through the low-temperature deposition with(NaF+KF)PDTs,the CZTSe device on glass yields the best efficiency of 8.1%with an improved Voc deficit of 646 mV.The developed deposition technologies have been applied to PI.For the first time,we report the highest efficiency of 6.92%for flexible CZTSe solar cells on PI.Additionally,CZTSe devices were utilized as bottom cells to fabricate four-terminal CZTSe/perovskite tandem cells because of a low bandgap of CZTSe(~1.0 eV)so that the tandem cell yielded an efficiency of 20%.The obtained results show that CZTSe solar cells prepared by a low-temperature process with in-situ alkali doping can be utilized for flexible thin-film solar cells as well as tandem device applications.
文摘The study on the removal of NOx from simulated flue gas has been carded out in a lab-scale bubbling reactor using acidic solutions of sodium chlorite. Experiments were performed at various pH values and inlet NO concentrations in the absence or presence of SO2 gas at 45℃. The effect of SO2 on NO oxidation and NO2 absorption was critically examined. The oxidative ability of sodium chlorite was investigated at different pH values and it was found to be a better oxidant at a pH less than 4. In acidic medium, sodium chlorite decomposed into C102 gas, which is believed to participate in NO oxidation as well as in NO2 absorption. A plausible NOx removal mechanism using acidic sodium chlorite solution has been postulated. A maximum NOx removal efficiency of about 81% has been achieved.
基金supported by Korea Ministry of Environment (MOE) as "Human Resource Development Project for Waste to Energy"
文摘The carbon dioxide （CO2） removal efficiency, reaction rate, and CO2 loading into aqueous blended monoethanolamine （MEA） ＋ 2-amino-2-methyl-l-propanol （AMP） solutions to enhance absorption characteristics of MEA and AMP were carried out by the absorption/regeneration process. As a result, compared to aqueous MEA and AMP solutions, aqueous blended MEA ＋ AMP solutions have a higher CO2 loading than MEA and a higher reaction rate than AMP. The CO2 loading of rich amine of aqueous 18 wt.% MEA ＋ 12 wt.% AMP solution was 0.62 mol CO2/mol amine, which is 51.2% more than 30 wt.% MEA （0.41 mol CO2/mol amine）. Consequently, blending MEA and AMP could be an effective way to design considering economical efficiency and used to operate absorber for a long time.
文摘The objective of the present study is to characterize the production of hydrogen with a sorptionenhanced steam-methane reaction process using Ca(OH)2 as the CO2 adsorbent. Theoretical equilibrium compositions at different operation conditions were calculated using an iterative method. It was found that with Ca(OH)2 as the CO2 sorbent, the concentration of CO2 adsorption was reduced in the product stream, that gave rise to higher methane conversion and higher H2 concentration. An experimental setup was built to test the theoretical calculation. The effects of sorbents and the particle size of Ca(OH)2 on the concentration of CO2 and H2 were investigated in detail. Results showed that the reactor packed with catalyst and Ca(OH)2 particles produced H2 concentration of 94%. It was nearly 96% of the theoretical equilibrium limit, much higher than H2 equilibrium concentration of 67.5% without CO2 sorption under the same conditions of 500℃, 0.2 MPa pressure and a steam-to-methane ratio 6. In addition, the residual mole fraction of CO2 was less than 0.001.
文摘Attempts have been made to generate euchlorine gas by chlorate-chloride process and to utilize it further to clean up SO2 and NOx from the flue gas in a lab scale bubbling reactor. Preliminary experiments were carded out to determine the gas and liquid phase mass transfer coefficients and their correlation equations have been established. Simultaneous removal of SO2 and NOx from the simulated flue gas using aqueous euchlorine scrubbing solution has been investigated. Euchlorine oxidized NO into NO2 completely and the later subsequently absorbed into the scrubbing solution in the form of nitrate. SO2 removal efficiency around 100% and NOx removal efficiency around 72% were achieved under optimal conditions. Mass balance has been confirmed by analyzing the sulfate, nitrate, euchlorine and chloride ion using ion chromatograph/auto-titrator and comparing it with their corresponding calculated values.
基金This study was supported by the National Research Foundation of Korea(NRF)grant funded by the Korea government(MSIT)(No.2019R1F1A1062193).
文摘Pt-Ni alloy nanocrystals with Pt-enriched shells were prepared by selective etching of surface Ni using sulfuric acid and hydroquinone.The changes in the electronic and geometric structure of the alloy nanoparticles at the surface were elucidated from the electrochemical surface area,the potential of zero total charge(PZTC),and relative surface roughness,which were determined from CO-and CO_(2)-displacement experiments before and after 3000 potential cycles under oxygen reduction reaction conditions.While the highest activity and durability were achieved in hydroquinone-treated Pt–Ni,sulfuric acidtreated one showed the lower activity and durability despite its higher surface Pt concentration and alloying level.Both PZTC and QCO_(2)/QCO ratio(desorption charge of reductively adsorbed CO_(2) normalized by COad-stripping charge)depend on surface roughness.In particular,QCO_(2)/QCO ratio change better reflects the roughness on an atomic scale,and PZTC is also affected by the electronic modification of Pt atoms in surface layers.In this study,a comparative study is presented to find a relationship between surface structure and electrochemical properties,which reveals that surface roughness plays a critical role to improve the electrochemical performance of Pt-Ni alloy catalysts with Pt-rich surfaces.
基金Supported by the Research and Development Program of the Korea Institute of Energy Research(KIER)(B4-2431-04)the National Natural Science Foundation of China(21276129,20876079)the Natural Science Funds for Distinguished Young Scholar in Shandong Province(JQ200904)
文摘The chemical looping gasification uses an oxygen carrier for solid fuel gasification by supplying insufficient lattice oxygen. The effect of gasifying medium on the coal chemical looping gasification with Ca SO4 as oxygen carrier is investigated in this paper. The thermodynamical analysis indicates that the addition of steam and CO2 into the system can reduce the reaction temperature, at which the concentration of syngas reaches its maximum value.Experimental result in thermogravimetric analyzer and a fixed-bed reactor shows that the mixture sample goes through three stages, drying stage, pyrolysis stage and chemical looping gasification stage, with the temperature for three different gaseous media. The peak fitting and isoconversional methods are used to determine the reaction mechanism of the complex reactions in the chemical looping gasification process. It demonstrates that the gasifying medium(steam or CO2) boosts the chemical looping process by reducing the activation energy in the overall reaction and gasification reactions of coal char. However, the mechanism using steam as the gasifying medium differs from that using CO2. With steam as the gasifying medium, parallel reactions occur in the beginning stage, followed by a limiting stage shifting from a kinetic to a diffusion regime. It is opposite to the reaction mechanism with CO2 as the gasifying medium.
文摘The influence of the dehydration by metal oxides on the synthesis of dimethyl carbonate （DMC） via oxidative carbonylation of methanol was studied. A Cu/Y-zeolite catalyst was prepared by the ion exchange method from CuCl2.2H2O and the commercial NH4-form of the Y type zeolite, The catalyst was characterized by X-ray fluorescence （XRF）, N2 adsorption （BET method）, X-ray diffraction （XRD）, and temperature-programmed de- sorption of ammonia （NH3-TPD） to evaluate its Cu and Cl content, surface area, structure, and acidity. Reaction tests were carried out using an autoclave （batch reactor） for 18 h at 403 K and 5.5 MPa （2CH3OH ＋ 1/2O2 ＋ CO （CH3O）2CO ＋ H2O）. The influence of various dehydrating agents （ZnO, MgO, and CaO） was examined with the aim of increasing the methanol conversion （XMeOH, MeOH conversion）. The MeOH conversion increased upon addition of metal oxides in the order CaO 〉〉 MgO 〉 ZnO, with the DMC selectivity （SDMC） following the order MgO 〉 CaO 〉 ZnO. The catalysts and dehydrating agents were characterized before and after the oxidative carbonylation of methanol by thermogravimetric and differential thermogravimetric （TG/DTG）, and XRD to con- firm that the dehydration reaction occurred via the metal oxide （MO ＋ H2O →M（OH）2）. The MeOH conversion increased from 8.7% to 14.6% and DMC selectivity increased from 39.0% to 53.1%, when using the dehydrating azent CaO.
基金supported by C1 Gas Refinery Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Science,ICT & Future Planning (2015M3D3A1A01064908)
文摘Alcohol-assisted low-temperature methanol synthesis was conducted over Cu/ZnO;catalysts while varying the copper content（X）. Unlike conventional methanol synthesis, ethanol acted as both solvent and reaction intermediate in this reaction, creating a different reaction pathway. The formation of crystalline phases and characteristic morphology of the co-precipitated precursors during the co-precipitation step were important factors in obtaining an efficient Cu/ZnO catalyst with a high dispersion of metallic copper,which is one of the main active sites for methanol synthesis. The acidic properties of the Cu/ZnO catalyst were also revealed as important factors, since alcohol esterification is considered the rate-limiting step in alcohol-assisted low-temperature methanol synthesis. As a consequence, bifunctionality of the Cu/ZnO catalyst such as metallic copper and acidic properties was required for this reaction. In this respect, the copper content（X） strongly affected the catalytic activity of the Cu/ZnO;catalysts, and accordingly, the Cu/ZnO;.5 catalyst with a high copper dispersion and sufficient acid sites exhibited the best catalytic performance in this reaction.
基金funded by the Korea Meteorological Institute (Grant No. KMI 2018-05410)
文摘A precipitation system developed continuously along the western coastline of the Korean Peninsula and created considerable precipitation both along the coast and inland on 26 July 2011. In this study, the causes for this nearshore convective system are investigated from observations and the results of model experiments. Three-dimensional radar fields clearly show that a change of wind at the surface border played an important role in the development of the nearshore convection system. The simulation results, which are very similar to the observations, show that the surface border generated and maintained the convergence zone. The roughness change enhanced the convergence, and the interaction between the deepening cold pool and downward flow maintained the convergence zone. The surface mechanical discontinuity affected by the roughness change between sea and land formed the convergence (gradient of wind stress), which induced momentum transfer to the upper layer. The cold pool created a steep gradient of potential temperature and provided the reason for the propagated convergence zone with the downward flow. The maximum value of the surface change factor, which comprises the influencing factors for the long-lasting convective system, reflects the enhancement of the system at the coast.
基金supported by Basic Science Research Program through the National Research Foundation of Korea(NRF) funded by the Ministry of Education,Science and Technology(Grant number 2012-0007231)
文摘Carbon deposition via coke formation is one of the critical problems causing catalyst deactivation during the reforming of hydrocarbons. An effort was made to regenerate the catalyst （Ni/γ-alumina） by oxidation methods. Two approaches were carded out for the regeneration of the deactivated catalyst. The first one involves the plasma treatment of the deactivated catalyst in the presence of dry air over a temperature range of 300-500℃, while the second one only the thermal treatment in the same temperature range. The performance of the regenerated catalyst was evaluated in terms of C4H10 and CO2 conversions and the physicochemical characteristics were examined using a surface area analyzer, an elemental analyzer, scanning electron microscopy （SEM） and transmission electron microscopy （TEM）. It was observed that the carbon deposit （coke） on the catalyst was about 9.89 wt% after reforming C4H10 for 5 h at 540℃. The simple thermal treatment at 400 ℃ reduced carbon content to 6.59 wt% whereas it was decreased to 3.25 wt% by the plasma and heat combination. The specific surface area was fully restored to the original state by the plasma-assisted regeneration at 500℃. As far as the catalytic activity is concerned, the fresh and regenerated catalysts exhibited similar C4H10 and CO2 conversion efficiencies.
基金supported by the National R&D Program through the National Research Foundation of Korea(NRF)funded by Ministry of Science and ICT(2021K1A4A8A01079455)。
文摘Ammonia (NH_(3)) plays a key role in the agricultural fertilizer and commodity chemical industries and is useful for exploring hydrogen storage carriers.The electrochemical nitrogen reduction reaction (NRR) is receiving attention as an environmentally sustainable NH_(3) synthesis replacement for the traditional Haber–Bosch process owing to its near ambient reaction conditions (<100℃ and 1 atm).However,its NH_(3) yield and faradaic efficiency are extremely low because of the sluggish kinetics of N≡N bond dissociation and the hindrance from competitive hydrogen evolution.To overcome these challenges,we herein introduce a dual-functionalized ionic liquid (1-(4-hydroxybutyl)-3-methylimidazolium hydroxide[HOBIM]OH) for a highly dispersed ruthenium oxide electrocatalyst to achieve a biased NRR.The observed uniform distribution of RuO_(2) on the carbon fiber and increase in the surface area for N_(2) adsorption by limiting proton access can be attributed to the presence of imidazolium ions.Moreover,extensive N_(2) adsorption contributes to enhanced NRR selectivity with an NH_(3) yield of 3.0×10^(-10)mol cm^(-2)s^(-1)(91.8μg h^(-1)mg^(-1)) and a faradaic efficiency of 2.2%at-0.20 V_(RHE).We expect our observations to provide new insights into the design of effective electrode structures for electrochemical NH;synthesis.
文摘In sludge treatment, drying sludge using typical technology with high water content to a water content of approximately 10% is always difficult because of adhesive characteristics of sludge in drying. Many methods have been applied, including direct and indirect heat drying, but these approaches of reducing water content to below 40% after drying are very inefficient in energy utilization of drying sludge. In this study, fry-drying technology with a high heat transfer coefficient of approximately 500 W/m2·°C was used to dry swine excreta, sewage and industrial sludge. Also waste oil was used in the fry-drying process, and because the oil’s boiling point is between 240°C and 340°C and the specific heat is approximately 60% of that of water. In the fry-drying system, the sludge is input by molding it into a designated form after heating the waste oil at temperatures between 130°C and 150°C. At these temperatures, the heated oil rapidly evaporates the water contained in the sludge, leaving the oil itself. After approximately 8 - 10 min, the water content of the sludge was less than 10%, and its heating value surpassed 20,000 kJ/kg. Indeed, this makes the organic sludge appropriate for use as a solid fuel. The dried swine excreta, sewage and industrial sludge can be used in an incinerator like low-rank coal or solid fuel.
文摘Characteristics of sulfur dioxide emission from coal and petroleum coke combustion were examined in a lab scale circulating fluidized bed (CFB) combustor. The rate constant of the first order rate expression for the absorption SO2 on the CaO surface was similar regardless of the origin of the limestone, the particle size and the initial SO2 concentration. However, the total SO2 absorption capacity was different depending on the origin of the limestone. The breakability of the particle which provides new surface for the reaction seems to play a major role in the absorption characteristics.
基金supported by the Korea Institute of Energy Technology Evaluation and Planning(KETEP)grant funded by the Korean government(MOTIE)(grant number:20202020800030).
文摘Heating,ventilation,and air conditioning(HVAC)systems account for one-third of the total energy consumption in office buildings.The use of airflow measurements to control the operation of HVAC systems can reduce energy consumption;thus,a sensor capable of monitoring airflow in a duct system is critical.Triboelectric nanogenerators(TENGs)can be utilized as self-powered sensors in airflow-driven TENGs(ATENGs)as self-powered sensors.By employing ferroelectric materials and surface modifications,the surface charges of TENGs can be increased.In this study,fibrous-mat TENGs were prepared using ferroelectric materials consisting of poly(vinylidene fluoride-co-trifluoroethylene)(PVDF-TrFE)and polyamide 11(nylon-11).And these materials were subsequently investigated.Poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate)was added to PVDF-TrFE to enhance the ferroelectric crystalline phase.X-ray diffraction analysis revealed that this incorporation affects theβphase.In addition,the surface of nylon-11 was modified using the electrospray technique for post-treatment,thereby improving the interfacial adhesion between the fibers.These materials were then utilized in fibrous-mat ATENGs(FM-ATENGs)to demonstrate their practical application.The FM-ATENGs can be effectively used in an Arduino airflowcheck sensor,showcasing their potential for application in HVAC systems,to enhance airflow control and energy efficiency.
基金conducted within the framework of a research and development program at the Korea Institute of Energy Research(Nos.C3-2420 and C4-2403).
文摘Traditional iridium (Ir) oxide catalysts have faced significant limitations in water electrolysis, particularly under acidic conditions where instability and degradation severely restrict the efficiency of the oxygen evolution reaction (OER) and hydrogen evolution reaction (HER). To overcome these challenges, this study successfully synthesized highly dispersed IrPtPdNi alloy nanoparticles on a graphene oxide support using a vertically moving reactor, demonstrating exceptional performance in water electrolysis. These nanoparticles, synthesized via a fast-moving bed pyrolysis method, combine iridium, platinum, palladium, and nickel. They exhibit lower overpotentials in OER and comparable performance in HER to commercial catalysts, while also offering enhanced stability. These results surpass the limitations of traditional catalysts, marking significant progress toward more efficient and sustainable hydrogen production technologies. This advancement is expected to contribute significantly to the development of sustainable energy systems by innovatively enhancing the performance of catalysts in the electrochemical water-splitting process.
基金the Basic Science Research Program(Nos.2021R1A2B5B03001615,2021M3H4A1A02099355,and 2021M3D1A2043791)through the National Research Foundation of Korea(NRF)grant by the Korean Government(MSIT).
文摘The rapid growth of miniaturized electronics has led to an urgent demand for microscale energy storage devices(MESDs)to sustainably power the micro electronic devices.However,most MESDs reported to date have suffered from the limited energy densities and shape versatility compared to conventional large-scale counterparts because of the architectural constraints inherent in microfabrication-based cell manufacturing and cell dimension/structure.This review addresses the cell architecture design for MESDs that can achieve both miniaturization and high energy density.We provide a comprehensive overview of five types of cell architectures of MESDs and their fabrication techniques.In addition,to enable practical applications of MESDs,several cell design approaches are presented with the aim of minimizing the inactive parts of the cell and maximizing the performance metrics of MESDs.Finally,we discuss development direction and outlook of MESDs with a focus on materials chemistry,energy-dense electrochemical systems,and cell performance normalization,which will help to expand their applications and manufacturing scalability.
