Electrocatalytic reduction of Cr(Ⅵ)to less toxic Cr(Ⅲ)is deemed as a promising technique.Conventional electrocatalytic reduction is always driven by a constant cathodic potential,which exhibits a repelling action to...Electrocatalytic reduction of Cr(Ⅵ)to less toxic Cr(Ⅲ)is deemed as a promising technique.Conventional electrocatalytic reduction is always driven by a constant cathodic potential,which exhibits a repelling action to Cr(Ⅵ)oxyanions in wastewater and consequently suppresses reduction kinetics.In order to remarkably accelerate Cr(Ⅵ)electrocatalytic reduction,we applied a pulsed potential on an Fe^(2+)-NiFe LDH/NF electrode synthesized by in situ growth of Fe^(2+)-doped NiFe LDH nanosheets on Ni foam using a spontaneous redox reaction.Under anodic potential section,HCrO_(4)^(–) anions are adsorbed on the electrode surface and reduced to Cr(Ⅲ)by Fe^(2+).Then,Cr(Ⅲ)ions are desorbed from the electrode surface under coulombic force.The regeneration of Fe^(2+) and direct reduction of Cr(Ⅵ)are achieved under cathodic potential section.The pulsed potential can achieve complete elimination of Cr(Ⅵ)within 60 min at an initial concentration of 10 mg L^(-1),and the removal efficiency shows a 60%increase with respect to that under constant cathodic potential.展开更多
The degradation of acid orange II(AO II)by a nanoporous Fe-Si-B(NP-Fe Si B)electrode under the pulsed square-wave potential has been investigated in this research.Defect-enriched NP-Fe Si B electrode was fabricated th...The degradation of acid orange II(AO II)by a nanoporous Fe-Si-B(NP-Fe Si B)electrode under the pulsed square-wave potential has been investigated in this research.Defect-enriched NP-Fe Si B electrode was fabricated through dealloying of annealed Fe_(76)Si_(9)B_(15)amorphous ribbons.The results of UV-vis spectra and FTIR indicated that AO II solution was degraded efficiently into unharmful molecules H_(2)O and CO_(2)on NPFe Si B electrode within 5 mins under the square-wave potential of±1.5 V.The degradation efficiency of the NP-Fe Si B electrode remains 98.9%even after 5-time recycling.The large amount of active surface area of the nanoporous Fe Si B electrode with lattice disorders and stacking faults,and alternate electrochemical redox reactions were mainly responsible for the excellent degradation performance of the NP-Fe Si B electrode.The electrochemical pulsed square-wave process accelerated the redox of Fe element in Fe-based nanoporous electrode and promoted the generation of hydroxyl radicals(·OH)with strong oxidizability as predominant oxidants for the degradation of azo dye molecules,which was not only beneficial to improving the catalytic degradation activity,but also beneficial to enhancing the reusability of the nanoporous electrode.This work provides a highly possibility to efficiently degrade azo dyes and broadens the application fields of nanoporous metals.展开更多
The composites of poly[Ni（salen）] and multi-walled carbon nanotube （MWCNT） were synthesized by pulse potentiostatic method. The composites were characterized by field emission scanning electron microscopy, Fourier...The composites of poly[Ni（salen）] and multi-walled carbon nanotube （MWCNT） were synthesized by pulse potentiostatic method. The composites were characterized by field emission scanning electron microscopy, Fourier transform infrared spectra, and electrochemical impedance spectroscopy. The wrapping of carbon nanotubes with poly[Ni（salen）] varied significantly with anodic pulse duration. Variance of structure of poly[Ni（salen）] caused by anodic pulse duration affected the ability of absorption to solvent molecules or solvated ions, which was indicated by v （C≡N） intensity. The ability to store/release charge of poly[Ni（salen）] caused by redox switching was evaluated in the form of low-frequency capacitance. Correlations of chargetransfer resistance/ionic diffusion resistance with potential and anodic pulse duration were investigated.展开更多
One fundamental question facing electrocatalytic CO_(2)reduction reaction(CO_(2)RR)is how to identify and correlate the local catalyst activity and stability to their bulk performance.Here we develop a versatile scann...One fundamental question facing electrocatalytic CO_(2)reduction reaction(CO_(2)RR)is how to identify and correlate the local catalyst activity and stability to their bulk performance.Here we develop a versatile scanning electrochemical microscopy(SECM)platform to directly analyze catalyst stability,CO_(2)RR product distribution,and chemical environment in complex systems at the microscopic scale.Using two Cu-porphyrin complex isomers as molecular catalysts,we have demonstrated that alternating the Cu-complex catalyst center to asymmetric Cu-N3C structure leads to reduced stability under constant potential electrolysis but increases the electrocatalytic activity under pulsed potential electrolysis.Testing the electroreduction properties of the catalysts in diff erent electrolysis modes,we find alternating electrolysis pattern changes the catalyst product selectivity and the local pH environment at the vicinity of the catalyst surface,which sheds light on the origin of improved hydrocarbon propagation.This work introduces a fast,efficient,and multifunctional SECM technique for evaluating fundamental and mechanistic aspects of CO_(2)RR in situ.展开更多
基金financially supported by the National Natural Science Foundation of China(NSFC)(Nos.62004137,21878257 and 21978196)the Natural Science Foundation(NSF)of Shanxi Province(No.201701D221083)+5 种基金the Key Research and Development Program of Shanxi Province(No.201803D421079)the Scientific and Technological Innovation Programs of Higher Education Institutions in Shanxi(No.2019L0156)the Shanxi Provincial Key Innovative Research Team in Science and Technology(No.201605D131045–10)the Research Project Supported by Shanxi Scholarship Council of China(2020–050)Horizontal Project(203010675-J)Liaoning Baiqianwan Talents Program。
文摘Electrocatalytic reduction of Cr(Ⅵ)to less toxic Cr(Ⅲ)is deemed as a promising technique.Conventional electrocatalytic reduction is always driven by a constant cathodic potential,which exhibits a repelling action to Cr(Ⅵ)oxyanions in wastewater and consequently suppresses reduction kinetics.In order to remarkably accelerate Cr(Ⅵ)electrocatalytic reduction,we applied a pulsed potential on an Fe^(2+)-NiFe LDH/NF electrode synthesized by in situ growth of Fe^(2+)-doped NiFe LDH nanosheets on Ni foam using a spontaneous redox reaction.Under anodic potential section,HCrO_(4)^(–) anions are adsorbed on the electrode surface and reduced to Cr(Ⅲ)by Fe^(2+).Then,Cr(Ⅲ)ions are desorbed from the electrode surface under coulombic force.The regeneration of Fe^(2+) and direct reduction of Cr(Ⅵ)are achieved under cathodic potential section.The pulsed potential can achieve complete elimination of Cr(Ⅵ)within 60 min at an initial concentration of 10 mg L^(-1),and the removal efficiency shows a 60%increase with respect to that under constant cathodic potential.
基金financially supported by Shi-changxu Innovation Center for Advanced Materials,Institute of Metal Research,Chinese Academy of Sciences,the National Natural Science Foundation of China(51790484,51671106)Chinese Academy of Sciences(ZDBSLY-JSC023)Fundamental Research Funds for the Central Universities(30919011404)。
文摘The degradation of acid orange II(AO II)by a nanoporous Fe-Si-B(NP-Fe Si B)electrode under the pulsed square-wave potential has been investigated in this research.Defect-enriched NP-Fe Si B electrode was fabricated through dealloying of annealed Fe_(76)Si_(9)B_(15)amorphous ribbons.The results of UV-vis spectra and FTIR indicated that AO II solution was degraded efficiently into unharmful molecules H_(2)O and CO_(2)on NPFe Si B electrode within 5 mins under the square-wave potential of±1.5 V.The degradation efficiency of the NP-Fe Si B electrode remains 98.9%even after 5-time recycling.The large amount of active surface area of the nanoporous Fe Si B electrode with lattice disorders and stacking faults,and alternate electrochemical redox reactions were mainly responsible for the excellent degradation performance of the NP-Fe Si B electrode.The electrochemical pulsed square-wave process accelerated the redox of Fe element in Fe-based nanoporous electrode and promoted the generation of hydroxyl radicals(·OH)with strong oxidizability as predominant oxidants for the degradation of azo dye molecules,which was not only beneficial to improving the catalytic degradation activity,but also beneficial to enhancing the reusability of the nanoporous electrode.This work provides a highly possibility to efficiently degrade azo dyes and broadens the application fields of nanoporous metals.
基金supports of this work by Beijing Natural Science Foundation(2093039)Program for New Century Excellent Talents in University of Ministry of Education of China (NCET-09-0215)State Key Laboratory of Multiphase Complex Systems (MPCS-2011-D-08)
文摘The composites of poly[Ni（salen）] and multi-walled carbon nanotube （MWCNT） were synthesized by pulse potentiostatic method. The composites were characterized by field emission scanning electron microscopy, Fourier transform infrared spectra, and electrochemical impedance spectroscopy. The wrapping of carbon nanotubes with poly[Ni（salen）] varied significantly with anodic pulse duration. Variance of structure of poly[Ni（salen）] caused by anodic pulse duration affected the ability of absorption to solvent molecules or solvated ions, which was indicated by v （C≡N） intensity. The ability to store/release charge of poly[Ni（salen）] caused by redox switching was evaluated in the form of low-frequency capacitance. Correlations of chargetransfer resistance/ionic diffusion resistance with potential and anodic pulse duration were investigated.
基金supported by the National Natural Science Foundation of China(22204115,22072101)the Natural Science Foundation of Jiangsu Province(BK20220485)+1 种基金the Suzhou Municipal Science and Technology Bureau(ZXL2022494)the start-up research grant for a distinguished professor at Soochow University(J.H.)。
文摘One fundamental question facing electrocatalytic CO_(2)reduction reaction(CO_(2)RR)is how to identify and correlate the local catalyst activity and stability to their bulk performance.Here we develop a versatile scanning electrochemical microscopy(SECM)platform to directly analyze catalyst stability,CO_(2)RR product distribution,and chemical environment in complex systems at the microscopic scale.Using two Cu-porphyrin complex isomers as molecular catalysts,we have demonstrated that alternating the Cu-complex catalyst center to asymmetric Cu-N3C structure leads to reduced stability under constant potential electrolysis but increases the electrocatalytic activity under pulsed potential electrolysis.Testing the electroreduction properties of the catalysts in diff erent electrolysis modes,we find alternating electrolysis pattern changes the catalyst product selectivity and the local pH environment at the vicinity of the catalyst surface,which sheds light on the origin of improved hydrocarbon propagation.This work introduces a fast,efficient,and multifunctional SECM technique for evaluating fundamental and mechanistic aspects of CO_(2)RR in situ.
