In Situ Carbon Encapsulation Confined Nickel-Doped Indium Oxide Nanocrystals for Boosting CO₂ Electroreduction to the Industrial Level

The reaction current density for the CO 2 electroreduction to formate of indium-based catalysts cannot meet the needs of industrial applications. Herein, the nickel-doped indium oxide nanocrystals (∼7 nm) confined in carbon nanofibers (Ni-In 2 O 3 @C NFs) demonstrate a formate partial current density of over 350 mA cm –2 at a moderate overpotential of 0.8 V, and particularly, the formate Faradaic efficiency (FE) is above 90% in a wide potential region from −0.6 to −1.0 V. More remarkably, a long-term stability of 55 h with an industrially relevant current density of ∼200 mA cm –2 can be achieved after improving hydrophobicity of gas diffusion electrodes (GDEs). Experimental results combined with DFT calculations confirm that the enhanced activity is attributed to the synergistic effect of nickel doping and carbon encapsulation in engineering the electronic structure of In 2 O 3 nanocrystals, which enhances the adsorption strength of OCHO* intermediates and accelerates the charge transfer rate.