Insights into the alloy-support synergistic effects for the CO2 hydrogenation towards methanol on oxide-supported Ni5Ga3 catalysts: An experimental and DFT study

Supported Ni-Ga alloys have emerged as potential catalyst to mitigate CO2 emissions by its conversion into methanol at mild conditions, however, its performance depends on the optimization of the alloy-support effects, which is unclear up to now. Herein, we investigate the influence of alloy-support synergy in the catalytic performance of Ni5Ga3 supported on SiO2, CeO2, and ZrO2, by combining in-depth structural, chemical and spectroscopic characterization and density functional theory (DFT) calculations. In situ DRIFTS confirmed further hydrogenation of key reaction intermediates in Ni5Ga3/ZrO2 surface, while weak CO2 adsorption in Ni5Ga3/SiO2 avoided intermediate stabilization on the surface and, strong interaction with Ni5Ga3/CeO2 poisoned interface active sites. Additionally, the relative energies of reactants and key intermediates in the three distinct regions of the catalyst (support surface, alloy surface, and alloy-support interface), calculated through DFT, allowed us to propose a reaction mechanism for the most promising catalyst, Ni5Ga3/ZrO2.