Modulating Charge Carrier Dynamics among Anisotropic Crystal Facets of Cu2O for Enhanced CO2 Photoreduction

Photogenerated charge separation is a crucial factor determining the enhancement in the energy efficiency of photocatalysts. In this work, through computational simulations of Cu2O crystals with different facets, edge-truncated cubic Cu2O was confirmed to enable efficient charge separation. To verify the computational predictions, Cu2O photocatalysts with two different morphologies and facet orientations, i.e., cubic and edge-truncated cubic structures, were synthesized and characterized. The photocatalytic activity toward the selective reduction of CO2 to methanol on the edge-truncated cubic Cu2O with anisotropic {100} and {110} facets was found to be nearly 5.5-fold higher than that of cubic Cu2O with only {100} facets. This observed difference is ascribed to the effective separation and migration of photogenerated charge carriers as well as the selective accumulation of electrons and holes on different facets of edge-truncated cubic Cu2O crystals. The effects of work function differences between {110} and {100} facets on the electronic band structure and anisotropic charge separation were also identified. These findings provide important guidelines for the design and synthesis of highly efficient and well-defined photocatalysts for CO2 conversion to fuel.