Developing cost-effective and high-activity catalysts for the methanolysis of ammonia borane(AB)has attracted great attention in the field of hydrogen energy recently.Besides the modification of the electronic structu...Developing cost-effective and high-activity catalysts for the methanolysis of ammonia borane(AB)has attracted great attention in the field of hydrogen energy recently.Besides the modification of the electronic structure of the catalysts,external factors such as visible light irradiation can improve the efficiency of hydrogen production as well.In the present study,a Z-scheme heterostructured VO-Cu_(0.5)Ni_(0.5)O catalysts were constructed by introducing a plenteous phase interface and oxygen vacancy(Vo).The catalytic activity of as-prepared VO-Cu_(0.5)Ni_(0.5)O toward AB methanolysis has been improved dramatically with the assistance of visible light irradiation.The turnover frequency(TOF)under visible light irradiation was measured to be 29_(mol)H_(2)·mol_(cat.)^(-1)·min^(-1),which is 1.4 times larger than the TOF in the absence of visible light.Systematic characterization experiments and density functional theory(DFT)calculations were conducted to unveil the causation of enhanced catalytic activity.The results demonstrated that the enhancement of the catalytic activity of VO-Cu_(0.5)Ni_(0.5)O originated from the electronic structure modification induced by the formation of heterojunctions,the introduction of oxygen vacancies,and the assistance of visible light cooperatively.The formation of heterojunction and the introduction of oxygen vacancies provoked the upshift of the d-band center;while the visible light irradiation induced the photogenerated electrons to transfer from Cu to Ni sites at the interface.Such electron structure modulation is beneficial for the construction of abundant active sites,thereby enhancing the adsorption of methanol on the Ni sites,which is considered as the rate-determine step for the methanolysis of AB.The strong interaction between Ni and O weakened the O-H bond of methanol,accelerating the methanolysis of AB.These results demonstrate the utilization of combined heterojunction,oxygen vacancy,and visible light to explore highly active AB methanolysis catalysts,which should shed light on the exploration of more effective catalysts for AB methanolysis.展开更多
Ammonia borane(NH_(3)BH_(3),AB)has been regarded as a promising chemical hydrogen storage material owing to its high hydrogen density and superior stability.Thus,the development of low-cost and high-efficient heteroge...Ammonia borane(NH_(3)BH_(3),AB)has been regarded as a promising chemical hydrogen storage material owing to its high hydrogen density and superior stability.Thus,the development of low-cost and high-efficient heterogeneous catalysts for the dehydrogenation of AB has attracted considerable scholarly attention.In this study,heterostructured Co_(3)O_(4)-SnO_(2)catalysts containing oxygen vacancy(V_(o))with different Co/Sn atomic ratios(designated as V_(o)-Co-Sn_(5:x))were synthesized via a simple coprecipitation-calcination method under mild reaction conditions.The catalyst containing an optimized Co/Sn atomic ratio of 5:2(V_(o)-Co-Sn_(5:2))exhibited robust catalytic performance with a turnover frequency value of 17.6mol_(H2)·mol^(-1)_(metal)·min^(-1).Moreover,82.6%of the original activity of the catalyst was retained after 14 catalytic cycles,indicating the high stability of the catalyst.Diversified characterization combined with the density functional theory(DFT)calculation confirmed the transfer of electrons from Co_(3)O_(4)to Sn O_(2)and the distribution of the separated charges on SnO_(2)-Co_(3)O_(4)interface.The transfer of electrons and the distribution of charges facilitated the adsorption and activation of water on the catalyst,thus accelerating the dissociation of H_(2)O molecule(the ratedetermining step of AB hydrolysis).It was found that the V_(o)adjusted the electron structure of the catalysts rather than acted as active sites.These findings will provide researchers with useful information for designing cheap and highly efficient catalysts for catalytic AB hydrolysis.展开更多
基金supported the Natural Science Foundation of Guangdong Province(Nos.2022A1515140085,2022A1515111022 and 2022A1515110275)the Major and Special Project in the Field of Intelligent Manufacturing of the Universities in Guangdong Province(No.2020ZDZX2067)+2 种基金the Natural Science Foundation of Huizhou University(No.HZU202004)the Professorial and Doctoral Scientific Research Foundation of Huizhou University(No.2020JB046)the Open Project Program of Guangdong Provincial Key Laboratory of Electronic Functional Materials and Devices,Huizhou University(No.EFMDN2021004M).
文摘Developing cost-effective and high-activity catalysts for the methanolysis of ammonia borane(AB)has attracted great attention in the field of hydrogen energy recently.Besides the modification of the electronic structure of the catalysts,external factors such as visible light irradiation can improve the efficiency of hydrogen production as well.In the present study,a Z-scheme heterostructured VO-Cu_(0.5)Ni_(0.5)O catalysts were constructed by introducing a plenteous phase interface and oxygen vacancy(Vo).The catalytic activity of as-prepared VO-Cu_(0.5)Ni_(0.5)O toward AB methanolysis has been improved dramatically with the assistance of visible light irradiation.The turnover frequency(TOF)under visible light irradiation was measured to be 29_(mol)H_(2)·mol_(cat.)^(-1)·min^(-1),which is 1.4 times larger than the TOF in the absence of visible light.Systematic characterization experiments and density functional theory(DFT)calculations were conducted to unveil the causation of enhanced catalytic activity.The results demonstrated that the enhancement of the catalytic activity of VO-Cu_(0.5)Ni_(0.5)O originated from the electronic structure modification induced by the formation of heterojunctions,the introduction of oxygen vacancies,and the assistance of visible light cooperatively.The formation of heterojunction and the introduction of oxygen vacancies provoked the upshift of the d-band center;while the visible light irradiation induced the photogenerated electrons to transfer from Cu to Ni sites at the interface.Such electron structure modulation is beneficial for the construction of abundant active sites,thereby enhancing the adsorption of methanol on the Ni sites,which is considered as the rate-determine step for the methanolysis of AB.The strong interaction between Ni and O weakened the O-H bond of methanol,accelerating the methanolysis of AB.These results demonstrate the utilization of combined heterojunction,oxygen vacancy,and visible light to explore highly active AB methanolysis catalysts,which should shed light on the exploration of more effective catalysts for AB methanolysis.
基金financially supported by the Professorial and Doctoral Scientific Research Foundation of Huizhou University(Nos.2018JB036,2020JB046 and 2022JB009)the Major and Special Project in the Field of Intelligent Manufacturing of the Universities in Guangdong Province(No.2020ZDZX2067)+3 种基金the Natural Science Foundation of Huizhou University(No.HZU202004)Open Project Program of Guangdong Provincial Key Laboratory of Electronic Functional Materials and Devices,Huizhou University(Nos.EFMDN2021001Z and EFMDN2021004M)Youth Innovative Talents Project in Collegesand Universities in Guangdong Province(No.2019KQNCX151)Basic and Applied Basic Research Fund of Guangdong Province(No.2020A1515110038)。
文摘Ammonia borane(NH_(3)BH_(3),AB)has been regarded as a promising chemical hydrogen storage material owing to its high hydrogen density and superior stability.Thus,the development of low-cost and high-efficient heterogeneous catalysts for the dehydrogenation of AB has attracted considerable scholarly attention.In this study,heterostructured Co_(3)O_(4)-SnO_(2)catalysts containing oxygen vacancy(V_(o))with different Co/Sn atomic ratios(designated as V_(o)-Co-Sn_(5:x))were synthesized via a simple coprecipitation-calcination method under mild reaction conditions.The catalyst containing an optimized Co/Sn atomic ratio of 5:2(V_(o)-Co-Sn_(5:2))exhibited robust catalytic performance with a turnover frequency value of 17.6mol_(H2)·mol^(-1)_(metal)·min^(-1).Moreover,82.6%of the original activity of the catalyst was retained after 14 catalytic cycles,indicating the high stability of the catalyst.Diversified characterization combined with the density functional theory(DFT)calculation confirmed the transfer of electrons from Co_(3)O_(4)to Sn O_(2)and the distribution of the separated charges on SnO_(2)-Co_(3)O_(4)interface.The transfer of electrons and the distribution of charges facilitated the adsorption and activation of water on the catalyst,thus accelerating the dissociation of H_(2)O molecule(the ratedetermining step of AB hydrolysis).It was found that the V_(o)adjusted the electron structure of the catalysts rather than acted as active sites.These findings will provide researchers with useful information for designing cheap and highly efficient catalysts for catalytic AB hydrolysis.
