MOF-Transformed In2O3-x@C Nanocorn Electrocatalyst for Efficient CO2 Reduction to HCOOH
Chen Qiu, Kun Qian, Jun Yu, Mingzi Sun, Shoufu Cao, Jinqiang Gao, Rongxing Yu, Lingzhe Fang, Youwei Yao, Xiaoqing Lü, Tao Li, Bolong Huang, Shihe Yang
Abstract
Abstract For electrochemical CO 2 reduction to HCOOH, an ongoing challenge is to design energy efficient electrocatalysts that can deliver a high HCOOH current density ( J HCOOH ) at a low overpotential. Indium oxide is good HCOOH production catalyst but with low conductivity. In this work, we report a unique corn design of In 2 O 3- x @C nanocatalyst, wherein In 2 O 3- x nanocube as the fine grains dispersed uniformly on the carbon nanorod cob, resulting in the enhanced conductivity. Excellent performance is achieved with 84% Faradaic efficiency (FE) and 11 mA cm −2 J HCOOH at a low potential of − 0.4 V versus RHE. At the current density of 100 mA cm −2 , the applied potential remained stable for more than 120 h with the FE above 90%. Density functional theory calculations reveal that the abundant oxygen vacancy in In 2 O 3- x has exposed more In 3+ sites with activated electroactivity, which facilitates the formation of HCOO* intermediate. Operando X-ray absorption spectroscopy also confirms In 3+ as the active site and the key intermediate of HCOO* during the process of CO 2 reduction to HCOOH.