Nanostructured iron oxyhydroxide（Fe OOH） thin films have been synthesized using an electrodeposition method on a nickel foam（NF） substrate and effect of air annealing temperature on the catalytic performance is st...Nanostructured iron oxyhydroxide（Fe OOH） thin films have been synthesized using an electrodeposition method on a nickel foam（NF） substrate and effect of air annealing temperature on the catalytic performance is studied. The as-deposited and annealed thin films were characterized by X-ray diffraction（XRD）,X-ray photoelectron spectroscopy（XPS）, field emission scanning electron microscopy（FE-SEM） and linear sweep voltammetry（LSV） to determine their structural, morphological, compositional and electrochemical properties, respectively. The as-deposited nanostructured amorphous Fe OOH thin film is converted into a polycrystalline Fe;O;with hematite crystal structure at a high temperature. The Fe OOH thin film acts as an efficient electrocatalyst for the oxygen evolution reaction（OER） in an alkaline 1 M KOH electrolyte. The film annealed at 200 °C shows high catalytic activity with an onset overpotential of 240 m V with a smaller Tafel slope of 48 m V/dec. Additionally, it needs an overpotential of 290 mV to the drive the current density of 10 m A/cm;and shows good stability in the 1 M KOH electrolyte solution.展开更多
Rational design of low‐cost and efficient electrocatalysts for ethanol oxidation reaction(EOR)is imperative for electrocatalytic ethanol fuel cells.In this work,we developed a copper‐doped nickel oxyhydroxide(Cu‐do...Rational design of low‐cost and efficient electrocatalysts for ethanol oxidation reaction(EOR)is imperative for electrocatalytic ethanol fuel cells.In this work,we developed a copper‐doped nickel oxyhydroxide(Cu‐doped NiOOH)catalyst via in situ electrochemical reconstruction of a NiCu alloy.The introduction of Cu dopants increases the specific surface area and more defect sites,as well as forms high‐valence Ni sites.The Cu‐doped NiOOH electrocatalyst exhibited an excellent EOR performance with a peak current density of 227 mA·cm^(–2)at 1.72 V versus reversible hydrogen electrode,high Faradic efficiencies for acetate production(>98%),and excellent electrochemical stability.Our work suggests an attractive route of designing non‐noble metal based electrocatalysts for ethanol oxidation.展开更多
Developing stable and efficient nonprecious-metal-based oxygen evolution catalysts in the neutral electrolyte is a challenging but essential goal for various electrochemical systems.Particularly,cobalt-based spinels h...Developing stable and efficient nonprecious-metal-based oxygen evolution catalysts in the neutral electrolyte is a challenging but essential goal for various electrochemical systems.Particularly,cobalt-based spinels have drawn a considerable amount of attention but most of them operate in alkali solutions.However,the frequently studied Co-Fe spinel system never exhibits appreciable stability in nonbasic conditions,not to mention attract further investigation on its key structural motif and transition states for activity loss.Herein,we report exceptional stable Co-Fe spinel oxygen evolution catalysts(~30%Fe is optimal)in a neutral electrolyte,owing to its unique metal ion arrangements in the crystal lattice.The introduced iron content enters both the octahedral and tetrahedral sites of the spinel as Fe^(2+)and Fe^(3+)(with Co ions having mixed distribution as well).Combining density functional theory calculations,we find that the introduction of Fe to Co_(3)O_(4)lowers the covalency of metal-oxygen bonds and can help suppress the oxidation of Co^(2+/3+)and 0^(2-).It implies that the Co-Fe spinel will have minor surface reconstruction and less lattice oxygen loss during the oxygen evolution reaction process in comparison with Co_(3)O_(4)and hence show much better stability.These findings suggest that there is still much chance for the spinel structures,especially using reasonable sublattices engineering via multimetal doping to develop advanced oxygen evolution catalysts.展开更多
高炉煤气中硫化氢(H_(2)S)的脱除对实现钢铁行业超低排放具有重要意义。高炉煤气经余压透平发电装置(Blast Furnace Top Gas Recovery Turbine Unit,TRT)后,温度在50~80℃之间,宜选用低温下活性较高的针铁矿(α-FeOOH)作为高炉煤气水解...高炉煤气中硫化氢(H_(2)S)的脱除对实现钢铁行业超低排放具有重要意义。高炉煤气经余压透平发电装置(Blast Furnace Top Gas Recovery Turbine Unit,TRT)后,温度在50~80℃之间,宜选用低温下活性较高的针铁矿(α-FeOOH)作为高炉煤气水解后H_(2)S的吸附剂。采用共沉淀结晶法将不同摩尔比(1%、5%、11%)的Zn^(2+)掺杂到α-FeOOH中,在模拟的高炉煤气气氛中,利用固定床-气相色谱联用平台测试其对H_(2)S的吸附容量,Zn/FeOOH硫容提升至292.2 mg/g,提高了137%。采用BET、EPR、XPS等分析手段对吸附剂的理化性质进行表征,分析结果表明,Zn/FeOOH样品的比表面积提升近60%。比表面积的增加意味着更多的反应界面可用于H_(2)S的吸附和转化,更多的吸附位点是提高硫容的关键因素之一。此外,孔容积提升约116%,孔容积的增加可以缓解反应产物带来的孔道堵塞效应。在g=2.002的位置,Zn/FeOOH系列样品均出现了氧空位的特征峰,Zn/FeOOH-11样品表现出最高的氧空位信号强度,表明掺杂Zn后材料中的氧空位显著增加。当Zn^(2+)被引入α-FeOOH晶格时,由于Zn^(2+)和Fe3+的离子半径和电荷不完全匹配,其替代Fe3+会在晶格中引入局部应力和畸变,有助于氧原子从晶格中逸出,形成氧空位。氧空位能为H_(2)S的吸附和活化提供活性位点,增强材料的催化活性。Zn掺杂α-FeOOH中单羟基比例增加到36%。单羟基是提高硫容的关键,作为活性较高的基团能够与H_(2)S形成氢键,从而增强材料表面的吸附。通过原位红外光谱分析,表明Zn不仅作为催化剂的一部分,还直接参与H_(2)S的反应形成ZnS,Zn掺杂不仅改善了α-FeOOH的催化性能,还影响了硫产物的种类。结构和表面性能的改变,显著提升了Zn/FeOOH材料对H_(2)S的吸附和转化能力,为吸附剂硫容提高及高炉煤气净化技术应用提供了参考。展开更多
Developing low-cost,active and durable electrocatalysts for oxygen evolution reaction(OER)is an urgent task for the applications such as water splitting and rechargeable metal-air battery.Herein,this work reports the ...Developing low-cost,active and durable electrocatalysts for oxygen evolution reaction(OER)is an urgent task for the applications such as water splitting and rechargeable metal-air battery.Herein,this work reports the fabrication of a metal and hetero atom co-doped fibrous carbon structure derived from cotton textile wastes and its use as an efficient OER catalyst.The free-standing fibrous carbon structure,fabricated with a simple two-step carbonization process,has a high specific surface area of 1796 m^2/g and a uniform distribution of Fe_(3)O_(4)/NiS nanoparticles(Fe_(3)O_(4)/NiS@CC).The composite exhibits excellent OER performance with an onset potential of 1.44 V and a low overpotential of 310 mV at the current density of 10 mA/cm^2in a 1.0 M KOH solution,which even surpass commercial Ru O_(2)catalyst.Additionally,this ternary catalyst shows remarkable long-term stability without current density loss after continuous operation for 26 h.It can be believed that the outstanding OER performance is attributed to the synergistic effect between the iron oxides and nickel sulphides,as well as the micro-meso porous carbon structure.This study demonstrates a new strategy to use conventional textile materials to prepare highly efficient electrocatalysts;it also provides a simple approach to turn textile waste into valuable products.展开更多
Efficient and robust noble-metal-free bifunctional electrocatalysts for overall water splitting(OWS)is of great importance to realize the large-scale hydrogen production.Herein,we report the growth of undoped and Cr-d...Efficient and robust noble-metal-free bifunctional electrocatalysts for overall water splitting(OWS)is of great importance to realize the large-scale hydrogen production.Herein,we report the growth of undoped and Cr-doped NiCo2O4(Cr-NiCo2O4)nanoneedles(NNs)on nickel foam(NF)as bifunctional electrocatalysts for both hydrogen evolution reaction(HER)and oxygen evolution reaction(OER).We demonstrate that Cr-doping significantly improves activity for HER and OER by increasing the conductivity of NNs and allowing more active sites on NNs electrochemically accessible.When amorphous FeOOH is electrodeposited on the surface of Cr-NiCo2O4 NNs,the resulting FeOOH/Cr-NiCo2O4/NF exhibits itself as an excellent bifunctional catalyst for OWS.In the two-electrode cell where FeOOH/Cr-NiCo2O4/NF is used both as cathode and anode for OWS,a cell voltage of only 1.65 V is required to achieve an electrolysis current density of 100 mA·cm^−2.In addition,the catalyst shows a very high stability for OWS,the two-electrode cell can operate at a consist current density of 20 mA·cm^−2 for 10 h OWS with the cell voltage being stable at ca.1.60 V.These results demonstrate that FeOOH/Cr-NiCo2O4/NF possesses an OWS performance superior to most of transition-metal based bifunctional electrocatalysts working in alkaline medium.The excellent bifunctional activity and stability of FeOOH/Cr-NiCo2O4/NF are attributed to the following reasons:(i)The NN structure provides a large specific surface area;(ii)the high conductivity of Cr-NiCo2O4 enables more active centers on the far-end part of NNs to be electrochemically reached;(iii)the deposition of FeOOH supplies additional active sites for OWS.展开更多
基金supported by the Human Resources Development program(no.20124010203180) of the Korea Institute of Energy Technology Evaluation and Planning(KETEP)Grant funded by the Korea government Ministry of Trade,Industry and Energysupported by Basic Science Research Program through the National Research Foundation of Korea(NRF) funded by the Ministry of Science,ICT and Future Planning(NRF-2015R1A2A2A01006856)
文摘Nanostructured iron oxyhydroxide（Fe OOH） thin films have been synthesized using an electrodeposition method on a nickel foam（NF） substrate and effect of air annealing temperature on the catalytic performance is studied. The as-deposited and annealed thin films were characterized by X-ray diffraction（XRD）,X-ray photoelectron spectroscopy（XPS）, field emission scanning electron microscopy（FE-SEM） and linear sweep voltammetry（LSV） to determine their structural, morphological, compositional and electrochemical properties, respectively. The as-deposited nanostructured amorphous Fe OOH thin film is converted into a polycrystalline Fe;O;with hematite crystal structure at a high temperature. The Fe OOH thin film acts as an efficient electrocatalyst for the oxygen evolution reaction（OER） in an alkaline 1 M KOH electrolyte. The film annealed at 200 °C shows high catalytic activity with an onset overpotential of 240 m V with a smaller Tafel slope of 48 m V/dec. Additionally, it needs an overpotential of 290 mV to the drive the current density of 10 m A/cm;and shows good stability in the 1 M KOH electrolyte solution.
文摘Rational design of low‐cost and efficient electrocatalysts for ethanol oxidation reaction(EOR)is imperative for electrocatalytic ethanol fuel cells.In this work,we developed a copper‐doped nickel oxyhydroxide(Cu‐doped NiOOH)catalyst via in situ electrochemical reconstruction of a NiCu alloy.The introduction of Cu dopants increases the specific surface area and more defect sites,as well as forms high‐valence Ni sites.The Cu‐doped NiOOH electrocatalyst exhibited an excellent EOR performance with a peak current density of 227 mA·cm^(–2)at 1.72 V versus reversible hydrogen electrode,high Faradic efficiencies for acetate production(>98%),and excellent electrochemical stability.Our work suggests an attractive route of designing non‐noble metal based electrocatalysts for ethanol oxidation.
基金the financial support by the National Natural Science Foundation of China(NSFC,grant nos.21905288 and 51904288)Zhejiang Provincial Natural Science Foundation(LZ21B030001)+3 种基金K.C.Wong Education Foundation(GJTD-2019-13)Ningbo major special projects of the Plan“Science and Technology Innovation 2025”(grant nos.2018B10056 and 2019B10046)Ningbo 3315 ProgramYongjiang Talent Introduction Program(no.2021A-115-G)
文摘Developing stable and efficient nonprecious-metal-based oxygen evolution catalysts in the neutral electrolyte is a challenging but essential goal for various electrochemical systems.Particularly,cobalt-based spinels have drawn a considerable amount of attention but most of them operate in alkali solutions.However,the frequently studied Co-Fe spinel system never exhibits appreciable stability in nonbasic conditions,not to mention attract further investigation on its key structural motif and transition states for activity loss.Herein,we report exceptional stable Co-Fe spinel oxygen evolution catalysts(~30%Fe is optimal)in a neutral electrolyte,owing to its unique metal ion arrangements in the crystal lattice.The introduced iron content enters both the octahedral and tetrahedral sites of the spinel as Fe^(2+)and Fe^(3+)(with Co ions having mixed distribution as well).Combining density functional theory calculations,we find that the introduction of Fe to Co_(3)O_(4)lowers the covalency of metal-oxygen bonds and can help suppress the oxidation of Co^(2+/3+)and 0^(2-).It implies that the Co-Fe spinel will have minor surface reconstruction and less lattice oxygen loss during the oxygen evolution reaction process in comparison with Co_(3)O_(4)and hence show much better stability.These findings suggest that there is still much chance for the spinel structures,especially using reasonable sublattices engineering via multimetal doping to develop advanced oxygen evolution catalysts.
文摘高炉煤气中硫化氢(H_(2)S)的脱除对实现钢铁行业超低排放具有重要意义。高炉煤气经余压透平发电装置(Blast Furnace Top Gas Recovery Turbine Unit,TRT)后,温度在50~80℃之间,宜选用低温下活性较高的针铁矿(α-FeOOH)作为高炉煤气水解后H_(2)S的吸附剂。采用共沉淀结晶法将不同摩尔比(1%、5%、11%)的Zn^(2+)掺杂到α-FeOOH中,在模拟的高炉煤气气氛中,利用固定床-气相色谱联用平台测试其对H_(2)S的吸附容量,Zn/FeOOH硫容提升至292.2 mg/g,提高了137%。采用BET、EPR、XPS等分析手段对吸附剂的理化性质进行表征,分析结果表明,Zn/FeOOH样品的比表面积提升近60%。比表面积的增加意味着更多的反应界面可用于H_(2)S的吸附和转化,更多的吸附位点是提高硫容的关键因素之一。此外,孔容积提升约116%,孔容积的增加可以缓解反应产物带来的孔道堵塞效应。在g=2.002的位置,Zn/FeOOH系列样品均出现了氧空位的特征峰,Zn/FeOOH-11样品表现出最高的氧空位信号强度,表明掺杂Zn后材料中的氧空位显著增加。当Zn^(2+)被引入α-FeOOH晶格时,由于Zn^(2+)和Fe3+的离子半径和电荷不完全匹配,其替代Fe3+会在晶格中引入局部应力和畸变,有助于氧原子从晶格中逸出,形成氧空位。氧空位能为H_(2)S的吸附和活化提供活性位点,增强材料的催化活性。Zn掺杂α-FeOOH中单羟基比例增加到36%。单羟基是提高硫容的关键,作为活性较高的基团能够与H_(2)S形成氢键,从而增强材料表面的吸附。通过原位红外光谱分析,表明Zn不仅作为催化剂的一部分,还直接参与H_(2)S的反应形成ZnS,Zn掺杂不仅改善了α-FeOOH的催化性能,还影响了硫产物的种类。结构和表面性能的改变,显著提升了Zn/FeOOH材料对H_(2)S的吸附和转化能力,为吸附剂硫容提高及高炉煤气净化技术应用提供了参考。
基金support from Australian Research Council(ARC)through ARC Centre of Excellence for Electromaterials Science(CE140100012)ARC Research Hub for Future Fibres(IH140100018)。
文摘Developing low-cost,active and durable electrocatalysts for oxygen evolution reaction(OER)is an urgent task for the applications such as water splitting and rechargeable metal-air battery.Herein,this work reports the fabrication of a metal and hetero atom co-doped fibrous carbon structure derived from cotton textile wastes and its use as an efficient OER catalyst.The free-standing fibrous carbon structure,fabricated with a simple two-step carbonization process,has a high specific surface area of 1796 m^2/g and a uniform distribution of Fe_(3)O_(4)/NiS nanoparticles(Fe_(3)O_(4)/NiS@CC).The composite exhibits excellent OER performance with an onset potential of 1.44 V and a low overpotential of 310 mV at the current density of 10 mA/cm^2in a 1.0 M KOH solution,which even surpass commercial Ru O_(2)catalyst.Additionally,this ternary catalyst shows remarkable long-term stability without current density loss after continuous operation for 26 h.It can be believed that the outstanding OER performance is attributed to the synergistic effect between the iron oxides and nickel sulphides,as well as the micro-meso porous carbon structure.This study demonstrates a new strategy to use conventional textile materials to prepare highly efficient electrocatalysts;it also provides a simple approach to turn textile waste into valuable products.
基金We gratefully acknowledge the financial support of this work by the National Natural Science Foundation of China(Nos.51872015 and 51672017).
文摘Efficient and robust noble-metal-free bifunctional electrocatalysts for overall water splitting(OWS)is of great importance to realize the large-scale hydrogen production.Herein,we report the growth of undoped and Cr-doped NiCo2O4(Cr-NiCo2O4)nanoneedles(NNs)on nickel foam(NF)as bifunctional electrocatalysts for both hydrogen evolution reaction(HER)and oxygen evolution reaction(OER).We demonstrate that Cr-doping significantly improves activity for HER and OER by increasing the conductivity of NNs and allowing more active sites on NNs electrochemically accessible.When amorphous FeOOH is electrodeposited on the surface of Cr-NiCo2O4 NNs,the resulting FeOOH/Cr-NiCo2O4/NF exhibits itself as an excellent bifunctional catalyst for OWS.In the two-electrode cell where FeOOH/Cr-NiCo2O4/NF is used both as cathode and anode for OWS,a cell voltage of only 1.65 V is required to achieve an electrolysis current density of 100 mA·cm^−2.In addition,the catalyst shows a very high stability for OWS,the two-electrode cell can operate at a consist current density of 20 mA·cm^−2 for 10 h OWS with the cell voltage being stable at ca.1.60 V.These results demonstrate that FeOOH/Cr-NiCo2O4/NF possesses an OWS performance superior to most of transition-metal based bifunctional electrocatalysts working in alkaline medium.The excellent bifunctional activity and stability of FeOOH/Cr-NiCo2O4/NF are attributed to the following reasons:(i)The NN structure provides a large specific surface area;(ii)the high conductivity of Cr-NiCo2O4 enables more active centers on the far-end part of NNs to be electrochemically reached;(iii)the deposition of FeOOH supplies additional active sites for OWS.
