Gallium Nitride-based Materials as Promising Catalysts for CO2 Reduction: A DFT Study on the Effect of CO2 Coverage and the Incorporation of Mg Doping or Substitutional In

Catalytic CO2 conversion to fuels and chemicals is important for mitigating the climate change and reducing the dependence on fossil resources. In order to achieve this goal on a large industrial level, effective catalysts need to be developed. Among them, gallium nitride (GaN) and related Mg-doped and In-alloyed systems have been proven as efficient materials for the reduction of highly stable CO2 molecules. This work presents a density functional theory (DFT) investigation, performing periodic boundary condition (PBC) calculations which allow to employ a more extended surface for a detailed analysis of the CO2 coverage, and the effect of Mg doping and In alloying on the CO2 adsorption and its conversion to CO. The results show the great potential of GaN(100) surfaces to simultaneously bind and strongly activate multiple CO2 molecules, which is a crucial aspect for an efficient CO2 conversion process. Moreover, the presence of Mg-dopant on the top layer is found to be more beneficial for the CO2 adsorption and activation with respect to both the pristine and In-alloyed system, and this effect is further improved by the inclusion of a second impurity on the top layer. In line with the previous experimental findings, these calculations support the potential of pristine GaN(100) to catalyze the CO2-to-CO reduction. The results presented here offer crucial information for the development of more efficient and selective catalysts for the CO2 reduction.