In this paper,yolk-shell structured ZnFe_(2)O_(4) microspheres assembled using nanoparticles are prepared using a facile solvothermal method and annealing treatment.Through a series of time-dependent experiments,the f...In this paper,yolk-shell structured ZnFe_(2)O_(4) microspheres assembled using nanoparticles are prepared using a facile solvothermal method and annealing treatment.Through a series of time-dependent experiments,the formation mechanism of the yolk-shell structured ZnFe_(2)O_(4) microspheres is attributed to the Ostwald ripening process.It is worth noting that the yolk-shell structured ZnFe_(2)O_(4) microspheres show a high surface area of 69.94 m^(2) g^(-1) with a total pore volume of 5.54 cm^(3) g^(-1).The as-prepared yolk-shell structured ZnFe_(2)O_(4) microspheres exhibit an overpotential of 280 mV at a current density of 10 mA cm^(-2) and the Tafel slope is 70 mV dec^(-1) which results in excellent electrocatalytic oxygen evolution capability.Compared with ZnFe_(2)O_(4) particles(without yolk-shell structure),the superior oxygen evolution reaction property can be attributed to one of the most important factors:namely the mesopore/macropore structure with a high surface area and the unique yolk-shell morphology assembled by nanoparticles,which can provide more active sites and enhance the contact of the reactant and active sites to help the transfer of electrons,thereby improving the catalytic activity.展开更多
Building efficient,durable,and inexpensive catalysts to promote hydrogen production from hydrazine borane(N_(2)H_(4)BH_(3))is crucial,but it remains a huge challenge.In this work,we report a simple and green wet chemi...Building efficient,durable,and inexpensive catalysts to promote hydrogen production from hydrazine borane(N_(2)H_(4)BH_(3))is crucial,but it remains a huge challenge.In this work,we report a simple and green wet chemical method to prepare Cr-modified Ni nanoparticles(NPs)immobilized on carbon doped mesoporous TiO_(2)(CTO).Three different morphologies(nanosphere(NS),nanoflake(NF),and nanorod(NR))of CTO were synthesized using ethanol and/or glycerol by the hydrothermal process.It was found that the CTO morphology has a significant impact on the size,dispersion,and electronic structure of Ni–Cr NPs.Clearly,compared with CTO–NS and CTO–NR,CTO–NF-supported Ni–Cr NPs exhibited 100%H_(2)selectivity and the best catalytic performance for hydrogen production from N_(2)H_(4)BH_(3).The turnover frequency(TOF)value of Ni–Cr/CTO–NF reached 555 h^(-1)at 323 K,which exceeded almost all reported noble-metal-free catalysts.More importantly,the catalytic performance of Ni–Cr/CTO–NF in N_(2)H_(4)BH_(3)dehydrogenation did not decrease significantly after 20 runs.Its ultra-high catalytic activity and significant durability are attributed to the small electron rich Ni–Cr NPs caused by the unique nanoflake structure of CTO–NF.This work provides ideas for constructing catalysts with different structures and lays the foundation for the development of efficient and cheap hydrogen production catalysts.展开更多
基金supported by the Natural Science Foundation of Anhui Province(1708085ME96 and 1608085QE90)the National Natural Science Foundation of China(11504120,51571166 and 61505167)+2 种基金the Key Natural Science Research Project for Colleges and Universities of Anhui Province(KJ2016A638)the Basic Research Fund for Free Exploration(JCYJ20170815161437298)the Project of Shaanxi Young Stars in Science and Technology(2017KJXX-18).
文摘In this paper,yolk-shell structured ZnFe_(2)O_(4) microspheres assembled using nanoparticles are prepared using a facile solvothermal method and annealing treatment.Through a series of time-dependent experiments,the formation mechanism of the yolk-shell structured ZnFe_(2)O_(4) microspheres is attributed to the Ostwald ripening process.It is worth noting that the yolk-shell structured ZnFe_(2)O_(4) microspheres show a high surface area of 69.94 m^(2) g^(-1) with a total pore volume of 5.54 cm^(3) g^(-1).The as-prepared yolk-shell structured ZnFe_(2)O_(4) microspheres exhibit an overpotential of 280 mV at a current density of 10 mA cm^(-2) and the Tafel slope is 70 mV dec^(-1) which results in excellent electrocatalytic oxygen evolution capability.Compared with ZnFe_(2)O_(4) particles(without yolk-shell structure),the superior oxygen evolution reaction property can be attributed to one of the most important factors:namely the mesopore/macropore structure with a high surface area and the unique yolk-shell morphology assembled by nanoparticles,which can provide more active sites and enhance the contact of the reactant and active sites to help the transfer of electrons,thereby improving the catalytic activity.
基金National Natural Science Foundation of China(No.22162013 and 22162014)Jiangxi Provincial Natural Science Foundation(No.20232ACB214002)Sponsored Program for Academic and Technical Leaders of Major Disciplines of Jiangxi Province(No.20212BCJL23059)。
文摘Building efficient,durable,and inexpensive catalysts to promote hydrogen production from hydrazine borane(N_(2)H_(4)BH_(3))is crucial,but it remains a huge challenge.In this work,we report a simple and green wet chemical method to prepare Cr-modified Ni nanoparticles(NPs)immobilized on carbon doped mesoporous TiO_(2)(CTO).Three different morphologies(nanosphere(NS),nanoflake(NF),and nanorod(NR))of CTO were synthesized using ethanol and/or glycerol by the hydrothermal process.It was found that the CTO morphology has a significant impact on the size,dispersion,and electronic structure of Ni–Cr NPs.Clearly,compared with CTO–NS and CTO–NR,CTO–NF-supported Ni–Cr NPs exhibited 100%H_(2)selectivity and the best catalytic performance for hydrogen production from N_(2)H_(4)BH_(3).The turnover frequency(TOF)value of Ni–Cr/CTO–NF reached 555 h^(-1)at 323 K,which exceeded almost all reported noble-metal-free catalysts.More importantly,the catalytic performance of Ni–Cr/CTO–NF in N_(2)H_(4)BH_(3)dehydrogenation did not decrease significantly after 20 runs.Its ultra-high catalytic activity and significant durability are attributed to the small electron rich Ni–Cr NPs caused by the unique nanoflake structure of CTO–NF.This work provides ideas for constructing catalysts with different structures and lays the foundation for the development of efficient and cheap hydrogen production catalysts.
