MOF-Transformed InO@C Nanocorn Electrocatalyst for Efficient CO Reduction to HCOOH.

For electrochemical CO reduction to HCOOH, an ongoing challenge is to design energy efficient electrocatalysts that can deliver a high HCOOH current density (J) 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 InO@C nanocatalyst, wherein InO 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 J at a low potential of - 0.4 V versus RHE. At the current density of 100 mA cm, 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 InO has exposed more In sites with activated electroactivity, which facilitates the formation of HCOO* intermediate. Operando X-ray absorption spectroscopy also confirms In as the active site and the key intermediate of HCOO* during the process of CO reduction to HCOOH.