摘要
Fabricating highly efficient and robust oxygen reduction reaction(ORR)electrocatalysts is challenging but desirable for practical Zn-air batteries.As an early transition-metal oxide,zirconium dioxide(ZrO_(2))has emerged as an interesting catalyst owing to its unique characteristics of high stability,anti-toxicity,good catalytic activity,and small oxygen adsorption enthalpies.However,its intrinsically poor electrical conductivity makes it difficult to serve as an ORR electrocatalyst.Herein,we report ultrafine N-doped ZrO_(2) nanoparticles embedded in an N-doped porous carbon matrix as an ORR electrocatalyst(N-ZrO_(2)/NC).The N-ZrO_(2)/NC catalyst displays four-electron reduction of oxygen in O.1 M KOH,Upon employment in a Zn-air battery,N-ZrO,/NC presented an exellent activity and long-term durability with a half-wave potential(E,v2)of 0.84 V and a selectivity for the intriguing powerdensity of 185.9 mwcm^(-2).anda high secific capacity of 797.9 mA h gzni,exceeding those of commercial Pt/C(122.1 mw cm^(-2) and 782.5 mA h gzn),This excellent performance is mainly ttributed to the ultrafine ZrO_(2) nanoparticles the conductive carbon substrate,and the modifed electronic band structure of ZrO_(2) after N-doping.Density functional theory calculations demonstrated that N-doping can reduce the band-gap of ZrO_(2) from 3.96 eV to 3.33 eV through the hybridization of the p state of the N atom with the 2p state of the oxygen atom;this provides enhanced electrical conductivity and results in faster electron-transfer kinetics.This work provides a new approach for the design of other enhanced semiconductor and insulator materials.
基金
supported by the National Natural Science Foundation of China(Grants No.52025013,51622102)
Ministry of Science and Technology of China MOST(Grant No.2018YFB1502101)
the 111 Project(B12015),and the Fundamental Research Funds for the Central Universities.
