Atomic CoN_(3)S_(1) sites for boosting oxygen reduction reaction via an atomic exchange strategy

It is vitally important to develop high-efficiency low-cost catalysts to boost oxygen reduction reaction(ORR)for renewable energy conversion.Herein,an A-CoN_(3)S_(1)@C electrocatalyst with atomic CoN_(3)S_(1)active sites loaded on N,S-codoped porous carbon was produced by an atomic exchange strategy.The constructed A-CoN_(3)S_(1)@C electrocatalyst exhibits an unexpected half-wave potential(0.901 V vs.reversible hydrogen electrode)with excellent durability for ORR under alkaline conditions(0.1 M KOH),superior to the commercial platinum carbon(20 wt.%Pt/C).The outstanding performance of A-CoN_(3)S_(1)@C in ORR is due to the positive effect of S atoms doping on optimizing the electron structure of the atomic CoN_(3)S_(1)active sites.Moreover,the rechargeable zinc-air battery in which both A-CoN_(3)S_(1)@C and IrO_(2)were simultaneously served as cathode catalysts(A-CoN_(3)S_(1)@C&IrO_(2))exhibits higher energy efficiency,larger power density,as well as better stability,compared to the commercial Pt/C&IrO_(2)-based zinc-air battery.The present result should be helpful for developing lower cost and higher performance ORR catalysts which is expected to be used in practical applications in energy devices.

Regulating the coordination microenvironment of atomic bismuth sites in nitrogen-rich carbon nanosheets as anode for superior potassium-ion batteries

Carbon-based materials are recognized as anodes fulling of promise for potassium ion batteries(PIBs)due to advantages of affordable cost and high conductivity.However,they still face challenges including structural unstability and slow kinetics.It is difficult to achieve efficient potassium storage with unmodified carbonaceous anode.Herein,atomic bismuth(Bi)sites with different atom coordinations anchored on carbon nanosheets(CNSs)have been synthesized through a template method.The properties of prepared multi-doping carbon anodes Bi-N_(3)S_(1)/CNSs,Bi-N_(3)P_(1)/CNSs and Bi-N_(4)/CNSs were probed in PIBs.The configuration Bi-N_(3)S_(1) with stronger charge asymmetry exhibits superior potassium storage performance compared to Bi-N_(3)P_(1) and Bi-N_(4) configurations.The Bi-N_(3)S_(1)/CNSs display a rate capacity of 129.2 mAh g^(-1)even at 10 A g^(-1)and an impressive cyclability characterized by over 5000 cycles at 5 A g^(-1),on account of its optimal coordination environment with more active Bi centers and K^(+)adsorption sites.Notably,assembled potassium-ion full cell Mg-KVO//Bi-N_(3)S_(1)/CNSs also shows an outstanding cycling stability,enduring 3000 cycles at 2 A g^(-1).Therefore,it can be demonstrated that regulating the electronic structure of metallic centre M-N_(4) via changing the type of ligating atom is a feasible strategy for modifying carbon anodes,on the base of co-doping metal and non-metal.