Modulating electronic structure of amorphous indium oxide for efficient formate synthesis towards CO2 electroreduction

Tuning the electronic structure of catalysts is an efficient approach to optimize the catalytic performance of CO2 electroreduction. Herein, we constructed an efficient catalyst consisted of amorphous InOX with cottonlike structure spreading on N doped carbon (N-C) substrate to extend the catalysts-substrate interfaces for enhancing electron-transfer effect. The amorphous InOX growing on N-C substrate (InOX/N-C) exhibited an improved current density of -34.4 mA cm-2. Notably, a faradaic efficiency for formate (HCOO-) over the amorphous InOX/N-C reached 79.6% at -1.0 V versus reversible hydrogen electrode, 1.8 times as high as that (44.2%) over the amorphous InOX growing on carbon black substrate. Mechanistic studies revealed that the introduction of N-C as substrates accelerated charge-transfer process on the catalytic surface of InOX/N-C. Density functional theory calculations further revealed that the interactions between N-C substrate and InOX not only facilitated the potential-determining *HCOO protonation, but also inhabited hydrogen evolution, thus improving the catalytic performance for the production of HCOO-.