Built-in Electric Field Promotes Interfacial Adsorption and Activation of CO₂ for C₁ Products over a Wide Potential Window

Abstract

The unsatisfactory adsorption and activation of CO₂ suppress electrochemical reduction over a wide potential window. Herein, the built-in electric field (BIEF) at the CeO₂/In₂O₃ n-n heterostructure realizes the C₁ (CO and HCOO^-) selectivity over 90.0% in a broad range of potentials from -0.7 to -1.1 V with a maximum value of 98.7 ± 0.3% at -0.8 V. In addition, the C₁ current density (-1.1 V) of the CeO₂/In₂O₃ heterostructure with a BIEF is about 2.0- and 3.2-fold that of In₂O₃ and a physically mixed sample, respectively. The experimental and theoretical calculation results indicate that the introduction of CeO₂ triggered the charge redistribution and formed the BIEF at the interfaces, which enhanced the interfacial adsorption and activation of CO₂ at low overpotentials. Furthermore, the promoting effect was also extended to CeO₂/In₂S₃. This work gives a deep understanding of BIEF engineering for highly efficient CO₂ electroreduction over a wide potential window.