The sharp rise of CO2 in the atmosphere has become a potential threat to global climate,which results from the massive utilization of fossil fuel since the industry revolution.CO2 electroreduction provides us a new possibility of utilizing CO2 as a carbon feedstock for fuel and commercial chemicals generation.In this article,a new method is developed for synthesizing CuInS2 hollow nanostructures through the Kirkendall effect.The CuInS2 hollow nanostructures exhibit excellent catalytic activity for electrochemical reduction of CO2 with particular high selectivity,achieving high faradaic efficiency for HCOOH of 72.8％ at -0.7 V.To elucidate the mechanisms,operando electrochemical Raman spectroscopy is employed to examine the CO2 reduction process.This work provides new insights into the design of hollow nanostructures toward electrocatalytic CO2 conversion and offers us an effective and reliable way for real-time investigation of electrochemical CO2 reduction reaction processes.