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.

Automated summary

The study investigates the impact of different crystal facet structures of Cu2O on the charge separation efficiency of photocatalysts through computational simulations and experimental validation. It demonstrates that edge-truncated cubic Cu2O exhibits higher charge separation efficiency and elucidates the mechanism behind the influence of facet structure differences on electronic band structure and charge separation.