Sodium(Na)O_(2)batteries have high energy density and low cost.However,high polarization,complex discharge products,and low Coulombic efficiency(CE)lead to poor cyclability.Here,we proposed an atomically dispersed Ru ...Sodium(Na)O_(2)batteries have high energy density and low cost.However,high polarization,complex discharge products,and low Coulombic efficiency(CE)lead to poor cyclability.Here,we proposed an atomically dispersed Ru catalyst on nitrogen-doped graphene for Na-O_(2)batteries.The catalysts enable the discharge to proceed via a surface-mediated route,which leads to uniform deposition of Na_(2-x)O_(2)and low polarization during recharge.The first-principle calculation revealed that Ru-N_(4)complex in the catalyst has strong chemical adsorption to intermediate superoxides,facilitating uniform deposition and enhancing rapid kinetics.In contrast,Ru nanoparticles,despite the catalytic activity,induce bulk deposition via a solution-mediated route because the exposed graphene surface shows weak interaction to superoxides,thereby lowering CEs and cyclability.In brief,the atomically-dispersed Ru catalyst endows Na-O_(2)batteries with excellent electrochemical properties via a surface-mediated discharge.展开更多
High selectivity toward alkenes in oxidative dehydrogenation(ODH)of light alkanes makes boron-based materials promising Catalysts.However,many key mechanistic aspects are still debated due to the challenge of capturin...High selectivity toward alkenes in oxidative dehydrogenation(ODH)of light alkanes makes boron-based materials promising Catalysts.However,many key mechanistic aspects are still debated due to the challenge of capturing fleeting reaction intermediates.Kinetic analysis,including determining reaction orders and activation energy,could be informative for reactions involving radical intermediates but has not been extensively exploited.This Review summarizes the current understanding of the apparent alkane reaction order and the apparent activation energy in the boron-catalyzed ODH.Despite varying compositions and structures,a majority of boron-based catalysts share many common features,induding alkene selectivity,the evolution and the formation of active site,and the apparent kinetic properties.These common trends could be attributed to the shared gas-phase radical mediated reaction pathways and the formation of active hydroxylated boron oxide species on boron-containing materials under ODH conditions.Values of apparent alkane reaction orders and apparent activation energies are sensitive and reliable experimental measures of the contributions of the gas-phase radical-mediated and surface mediated pathways,suggesting the outline of a general mechanistic framework of the boron-catalyzed ODH.展开更多
基金the financial support of the National Natural Science Foundation of China(Nos.22075131,21776121)National Key R&D Program of China(No.2020YFA0406104)。
文摘Sodium(Na)O_(2)batteries have high energy density and low cost.However,high polarization,complex discharge products,and low Coulombic efficiency(CE)lead to poor cyclability.Here,we proposed an atomically dispersed Ru catalyst on nitrogen-doped graphene for Na-O_(2)batteries.The catalysts enable the discharge to proceed via a surface-mediated route,which leads to uniform deposition of Na_(2-x)O_(2)and low polarization during recharge.The first-principle calculation revealed that Ru-N_(4)complex in the catalyst has strong chemical adsorption to intermediate superoxides,facilitating uniform deposition and enhancing rapid kinetics.In contrast,Ru nanoparticles,despite the catalytic activity,induce bulk deposition via a solution-mediated route because the exposed graphene surface shows weak interaction to superoxides,thereby lowering CEs and cyclability.In brief,the atomically-dispersed Ru catalyst endows Na-O_(2)batteries with excellent electrochemical properties via a surface-mediated discharge.
基金National Natural Science Foundation of China(22172001 and 22108006)Beijing National Laboratory for Molecular Sciences.
文摘High selectivity toward alkenes in oxidative dehydrogenation(ODH)of light alkanes makes boron-based materials promising Catalysts.However,many key mechanistic aspects are still debated due to the challenge of capturing fleeting reaction intermediates.Kinetic analysis,including determining reaction orders and activation energy,could be informative for reactions involving radical intermediates but has not been extensively exploited.This Review summarizes the current understanding of the apparent alkane reaction order and the apparent activation energy in the boron-catalyzed ODH.Despite varying compositions and structures,a majority of boron-based catalysts share many common features,induding alkene selectivity,the evolution and the formation of active site,and the apparent kinetic properties.These common trends could be attributed to the shared gas-phase radical mediated reaction pathways and the formation of active hydroxylated boron oxide species on boron-containing materials under ODH conditions.Values of apparent alkane reaction orders and apparent activation energies are sensitive and reliable experimental measures of the contributions of the gas-phase radical-mediated and surface mediated pathways,suggesting the outline of a general mechanistic framework of the boron-catalyzed ODH.