The reconstruction during oxygen evolution reaction (OER) significantly affects the electronic and local geometry structure of metal sites in electrocatalyst.Compared with well-investigated cobalt-based materials,the ...The reconstruction during oxygen evolution reaction (OER) significantly affects the electronic and local geometry structure of metal sites in electrocatalyst.Compared with well-investigated cobalt-based materials,the reconstruction of rocksalt CoO with purely Co^(2+) in octahedral (Oh) coordination has not been revealed in detail.Herein,monolayer Co O supported on reduced graphene oxide (r GO) was synthesized via a one-pot hydrothermal strategy with calcinating in Ar atmosphere.The structure evolution of twodimension (2D) Co O/r GO during OER was revealed by in situ X-ray absorption spectroscopy (XAS).The transition from Co O toward Co3O_(4) already occurred at open circuit potential,further enhanced at 1.23 V (vs.RHE).The Co Ox(OH)ywas determined as the active phase at 1.53 V,displaying a tetrahedral Co coordination defective spinel Co_(3)O_(4) with the Co-O shell that featured the (oxy)hydroxide,not the standard Co OOH.After OER,the irreversible transition from CoO to Co_(3)O_(4) was observed.In contrast,in situ Raman spectra revealed a reversible amorphization process on Co_(3)O_(4)/r GO under operation conditions.Furthermore,this study indicated that the reconstruction behavior could be more effectively revealed by XAS using 2D materials.展开更多
Non-thermal plasma(NTP)catalysis is considered one of the most promising technologies to address a wide range of energy and environmental needs,such as carbon dioxide(CO_(2))conversion,NH3 synthesis,and volatile organ...Non-thermal plasma(NTP)catalysis is considered one of the most promising technologies to address a wide range of energy and environmental needs,such as carbon dioxide(CO_(2))conversion,NH3 synthesis,and volatile organic compounds(VOCs)removal.A systematic approach to optimizing NTP systems benefits from understanding VOCs'fundamental NTP destruction behavior and analyzing the correlations between molecular structures and conversion and selectivity.Herein,the mechanical performance of the toluene destruction in NTP is examined and compared with benzene bearing a similar molecular structure.Different experimental and theoretical techniques are applied,including synchrotron vacuum ultraviolet photoionization mass spectrometry(SVUV-PIMS),thermochemistry,and quantum chemistry.Comparatively,toluene is more readily destroyed under the same NTP conditions than benzene.More intriguingly,the distribution of the decomposition species is significantly different.The theoretical calculations reveal that the abundant methyl radicals generated in toluene decomposition mainly lead to the various species distribution.These radicals promote some reactions,such as the decomposition of o-benzoquinone,one of the key intermediates,thus leading to new reaction pathways and products different from benzene.Finally,the critical mechanistic steps of toluene decomposition under the present non-thermal plasma conditions are established,which include the interactions between toluene and electrons or reactive radicals,the cleavage of the aromatic ring,and the various reaction pathways involving of methyl radicals.This study presents an effective approach to elucidate the distinct fundamental reaction mechanisms arising from subtle structural differences,offering new insights into the underlying plasma chemistry crucial for advancing various promising environmental and energy applications of non-thermal plasma systems.展开更多
Non-thermal plasma(NTP)has been demonstrated as one of the promising technologies that can degrade volatile organic compounds(VOCs)under ambient condition.However,one of the key challenges of VOCs degradation in NTP i...Non-thermal plasma(NTP)has been demonstrated as one of the promising technologies that can degrade volatile organic compounds(VOCs)under ambient condition.However,one of the key challenges of VOCs degradation in NTP is its relatively low mineralization rate,which needs to be addressed by introducing catalysts.Therefore,the design and optimization of catalysts have become the focus of NTP coupling catalysis research.In thiswork,a series of two-dimensional nanosheet Co-Ni metal oxides were synthesized by microwave method and investigated for the catalytic oxidation of benzene in an NTP-catalysis coupling system.Among them,Co_(2)Ni_(1)O_(x)achieves 60%carbon dioxide(CO_(2))selectivity(SCO_(2))when the benzene removal efficiency(REbenzene)reaches more than 99%,which is a significant enhancement compared with the CO_(2)selectivity obtained without any catalysts(38%)under the same input power.More intriguingly,this SCO_(2)is also significantly higher than that of single metal oxides,NiO or Co_(3)O_(4),which is only around 40%.Such improved performance of this binary metal oxide catalyst is uniquely attributed to the synergistic effects of Co and Ni in Co_(2)Ni_(1)O_(x)catalyst.The introduction of Co_(2)Ni_(1)O_(x)was found to promote the generation of acrolein significantly,one of the key intermediates found in NTP alone system reported previously,suggest the benzene ring open reaction is promoted.Compared with monometallic oxides NiO and Co_(3)O_(4),Co_(2)Ni_(1)O_(x)also shows higher active oxygen proportion,better oxygenmobility,and stronger low-temperature redox capability.The above factors result in the improved catalytic performance of Co_(2)Ni_(1)O_(x)in the NTP coupling removal of benzene.展开更多
基金supported by the National Natural Science Foundation of China(21872093)the National Key Research and Development Program of China(2018YFB1502001)funding support from the Center of Hydrogen Science,Shanghai Jiao Tong University,China。
文摘The reconstruction during oxygen evolution reaction (OER) significantly affects the electronic and local geometry structure of metal sites in electrocatalyst.Compared with well-investigated cobalt-based materials,the reconstruction of rocksalt CoO with purely Co^(2+) in octahedral (Oh) coordination has not been revealed in detail.Herein,monolayer Co O supported on reduced graphene oxide (r GO) was synthesized via a one-pot hydrothermal strategy with calcinating in Ar atmosphere.The structure evolution of twodimension (2D) Co O/r GO during OER was revealed by in situ X-ray absorption spectroscopy (XAS).The transition from Co O toward Co3O_(4) already occurred at open circuit potential,further enhanced at 1.23 V (vs.RHE).The Co Ox(OH)ywas determined as the active phase at 1.53 V,displaying a tetrahedral Co coordination defective spinel Co_(3)O_(4) with the Co-O shell that featured the (oxy)hydroxide,not the standard Co OOH.After OER,the irreversible transition from CoO to Co_(3)O_(4) was observed.In contrast,in situ Raman spectra revealed a reversible amorphization process on Co_(3)O_(4)/r GO under operation conditions.Furthermore,this study indicated that the reconstruction behavior could be more effectively revealed by XAS using 2D materials.
基金supported by the National Natural Science Foundation of China(U1832155)National Key Research and Development Program of China(2017YFE0127500)。
文摘Non-thermal plasma(NTP)catalysis is considered one of the most promising technologies to address a wide range of energy and environmental needs,such as carbon dioxide(CO_(2))conversion,NH3 synthesis,and volatile organic compounds(VOCs)removal.A systematic approach to optimizing NTP systems benefits from understanding VOCs'fundamental NTP destruction behavior and analyzing the correlations between molecular structures and conversion and selectivity.Herein,the mechanical performance of the toluene destruction in NTP is examined and compared with benzene bearing a similar molecular structure.Different experimental and theoretical techniques are applied,including synchrotron vacuum ultraviolet photoionization mass spectrometry(SVUV-PIMS),thermochemistry,and quantum chemistry.Comparatively,toluene is more readily destroyed under the same NTP conditions than benzene.More intriguingly,the distribution of the decomposition species is significantly different.The theoretical calculations reveal that the abundant methyl radicals generated in toluene decomposition mainly lead to the various species distribution.These radicals promote some reactions,such as the decomposition of o-benzoquinone,one of the key intermediates,thus leading to new reaction pathways and products different from benzene.Finally,the critical mechanistic steps of toluene decomposition under the present non-thermal plasma conditions are established,which include the interactions between toluene and electrons or reactive radicals,the cleavage of the aromatic ring,and the various reaction pathways involving of methyl radicals.This study presents an effective approach to elucidate the distinct fundamental reaction mechanisms arising from subtle structural differences,offering new insights into the underlying plasma chemistry crucial for advancing various promising environmental and energy applications of non-thermal plasma systems.
基金supported by the National Key Research and Development Program of China(No.2017YFE0127500)National Natural Science Foundation of China(No.U1832155).
文摘Non-thermal plasma(NTP)has been demonstrated as one of the promising technologies that can degrade volatile organic compounds(VOCs)under ambient condition.However,one of the key challenges of VOCs degradation in NTP is its relatively low mineralization rate,which needs to be addressed by introducing catalysts.Therefore,the design and optimization of catalysts have become the focus of NTP coupling catalysis research.In thiswork,a series of two-dimensional nanosheet Co-Ni metal oxides were synthesized by microwave method and investigated for the catalytic oxidation of benzene in an NTP-catalysis coupling system.Among them,Co_(2)Ni_(1)O_(x)achieves 60%carbon dioxide(CO_(2))selectivity(SCO_(2))when the benzene removal efficiency(REbenzene)reaches more than 99%,which is a significant enhancement compared with the CO_(2)selectivity obtained without any catalysts(38%)under the same input power.More intriguingly,this SCO_(2)is also significantly higher than that of single metal oxides,NiO or Co_(3)O_(4),which is only around 40%.Such improved performance of this binary metal oxide catalyst is uniquely attributed to the synergistic effects of Co and Ni in Co_(2)Ni_(1)O_(x)catalyst.The introduction of Co_(2)Ni_(1)O_(x)was found to promote the generation of acrolein significantly,one of the key intermediates found in NTP alone system reported previously,suggest the benzene ring open reaction is promoted.Compared with monometallic oxides NiO and Co_(3)O_(4),Co_(2)Ni_(1)O_(x)also shows higher active oxygen proportion,better oxygenmobility,and stronger low-temperature redox capability.The above factors result in the improved catalytic performance of Co_(2)Ni_(1)O_(x)in the NTP coupling removal of benzene.
