Regulating p -orbital electronic configuration of In 2 O 3 by thickness-controlled carbon layer for efficient electrocatalytic CO 2 reduction to HCOOH

As for developing efficient Indium (In)-based catalyst of CO 2 reduction to HCOOH, the modulation of electronic structure stands as a pivotal factor. However, the precise control of p -orbital electronic configuration of In 2 O 3 remains challenging. Herein, the carbon-coated In 2 O 3 (In 2 O 3 @C) with precisely controllable carbon thickness is developed. The In 2 O 3 modified by moderate carbon layer thickness exhibits an impressive FE HCOOH exceeding 90 % and maintains a constant current density of 110 mA cm −2 even after 100 h. Meanwhile, it achieves a FE HCOOH of 97 % and a current of 550 mA in a membrane electrode assembly. The catalyst maintains satisfactory activity even under low CO 2 concentration and acidic electrolytes. The density functional theory (DFT) calculations show that carbon layer successfully improves the p -orbital electronic configuration of In 2 O 3 and perfects the adsorption energy of *OCHO intermediate. This work can provide a guidance for regulating electronic configuration and designing high-efficiency electrocatalyst.