Mechanistical investigation on the self-enhanced photocatalytic activity of CuO/Cu2O hybrid nanostructures by density functional theory calculations

Abstract

The photocatalytic mechanism of a Cu₂O/CuO hybrid system is disclosed in detail by density functional theory (DFT) calculations. The synergistic relationship of the two counterparts is confirmed by hydrogen peroxide (H₂O₂) formation on the CuO nanowires and dissociation on the Cu₂O nanoparticles; this enables the system to self-sufficiently produce hydroxyl radicals, which is highly efficient in the photocatalytic degradation of methyl orange. The exposed surfaces are found to be crucial in the cooperative photocatalytic system, especially the Cu₂O(111) surface, in the dissociation of H₂O₂. The distinct positions of the conduction band minimum and valence band maximum for CuO and Cu₂O and synergic surface reactions enable the effective utilization of the electrons and holes generated by visible-light irradiation. Our results will contribute to a greater understanding of the specific mechanism of photodegradation catalyzed by Cu₂O/CuO heterostructures, which may lead to promising directions in structure optimization for photocatalysts with high photocatalytic efficiency.