Co_(2)VO_(4) with Co tetrahedrons and octahedrons of transition metal oxides has achieved progress in electrocatalysts and batteries.However,high metal-metal interactions make it challenging to maintain high reactivit...Co_(2)VO_(4) with Co tetrahedrons and octahedrons of transition metal oxides has achieved progress in electrocatalysts and batteries.However,high metal-metal interactions make it challenging to maintain high reactivity as well as increase the conductivity and stability of supercapacitors.In this work,spinel-structured CoZn_(0.5)V_(1.5)O_(4) with a high specific surface area was synthesized through an ion-exchange process from the metal-organic frameworks of zinc-cobalt.Density functional theory calculations indicate that the replacement of transition metal by Zn can decrease the interaction between the transition metals,leading to a downshift in the π^(∗)-orbitals(V-O)and half-filled a_(1g) orbitals near the Fermi level,thus increasing the conductivity and stability of CoZn_(0.5)V_(1.5)O_(4).As a supercapacitor electrode,CoZn_(0.5)V_(1.5)O_(4) exhibits high cycling durability(99.4% capacitance retention after 18,000 cycles)and specific capacitance(1100mFcm^(-2) at 1mAcm^(-2)).This work provides the possibility of designing octahedral and tetrahedral sites in transition metal oxides to improve their electrochemical performance.展开更多
基金supported by the National Natural Science Foundation of China(51872204,52072261 and 22011540379)the National Key Research and Development Program of China(2017YFA0204600)+1 种基金Shanghai Social Development Science and Technology Project(20dz1201800)Shanghai Sailing Program(21YF1430900).
文摘Co_(2)VO_(4) with Co tetrahedrons and octahedrons of transition metal oxides has achieved progress in electrocatalysts and batteries.However,high metal-metal interactions make it challenging to maintain high reactivity as well as increase the conductivity and stability of supercapacitors.In this work,spinel-structured CoZn_(0.5)V_(1.5)O_(4) with a high specific surface area was synthesized through an ion-exchange process from the metal-organic frameworks of zinc-cobalt.Density functional theory calculations indicate that the replacement of transition metal by Zn can decrease the interaction between the transition metals,leading to a downshift in the π^(∗)-orbitals(V-O)and half-filled a_(1g) orbitals near the Fermi level,thus increasing the conductivity and stability of CoZn_(0.5)V_(1.5)O_(4).As a supercapacitor electrode,CoZn_(0.5)V_(1.5)O_(4) exhibits high cycling durability(99.4% capacitance retention after 18,000 cycles)and specific capacitance(1100mFcm^(-2) at 1mAcm^(-2)).This work provides the possibility of designing octahedral and tetrahedral sites in transition metal oxides to improve their electrochemical performance.
