Theoretical study of CO oxidation on Au1/Co3O4 (110) single atom catalyst using density functional theory calculations

Abstract

Single-atom catalyst (SAC) using Au1/Co3O4 has been under investigation experimentally for CO oxidation in recent years. However, the reaction mechanisms for CO oxidation on Au1/Co3O4 are still poorly understood. In this paper, theoretical investigations have been conducted to elucidate the catalytic mechanism of CO oxidation on the Au1/Co3O4 (110) and the pristine Co3O4 (110) by means of the spin-polarized density functional theory puls Hubbard U (DFT + U) calculations, respectively. The calculation results show that 1) the top site of Co3+ (site 1) is the most favorable anchored site for single Au atom on the Co3O4 (110); 2) CO molecule always anchored on the top of the Au atom by a C–Au bond; 3) O2 molecules can be only physisorbed on the single Au atom in whatever way; 4) CO2 molecule can be easily escaped from Au1/Co3O4 (110) at low temperature; 5) the catalytic mechanisms for CO oxidation by extracting the twofold-coordinate oxygen and threefold-coordinate oxygen on the pristine Co3O4 (110) are follow the Mars-van Krevelen mechanism, and the catalytic activity of CO oxidation on the pristine Co3O4 (110) O2f is better than that on O3f; 6) although the pristine Co3O4 (110) has some catalytic activities for CO oxidation, the catalytic activities are far below those of the Au1/Co3O4 (110) via the Eley-Rideal mechanism. In other words, the introducing of single atom Au into the pristine Co3O4 (110) can greatly enhance the catalytic activity of the pristine Co3O4 (110) for CO oxidation. The above results will help in understanding the theoretical mechanisms and the previous experimental results at the molecular lever, and provide a theory base for designing and fabrication of highly active and stable Co3O4 supported SACs.