MgH/CuO Hydrogen Storage Composite with Defect-Rich Surfaces for Carbon Dioxide Hydrogenation.

Thermal conversion of CO to value-added chemicals is challenging due to the extreme inertness of the CO molecule and the low selectivity of products. We reported a defect-rich MgH/CuO hydrogen storage composite from mechanochemical ball-milling for the catalytic hydrogenation of CO to lower olefins. The defect-rich MgH/CuO hydrogen storage composite achieves a C-C selectivity of 54.8% and a CO conversion of 20.7% at 350 °C under a low H/CO ratio of 1:5, which increases the efficiency of H utilization by offering lattice H species for hydrogenation. Density functional theory calculations show that the defective structure of MgH/CuO can promote CO molecule adsorption and activation, while the electronic structure of MgH is beneficial for offering lattice H for CO molecule hydrogenation. The lattice H can combine the C site of CO molecule to promote the formation of Mg formate, which can be further hydrogenated to lower olefins under a low H concentration. This work for CO conversion by a defect-rich MgH/CuO hydrogen storage composite can inspire the catalysts design for the hydrogenation of CO to lower olefins.