Three-dimensional porous Cu2O with dendrite for efficient photocatalytic reduction of CO2 under visible light

Cuprous oxide (Cu2O) is a promising photocatalyst that can reduce CO2 to fuel under visible light irradiation. However, the fast electron-hole recombination and photo-corrosion of Cu2O limit its photocatalytic performance. In order to overcome these two shortcomings of Cu2O, in this work, three-dimensional (3D) porous Cu2O with dendrite structure was prepared by electrodeposition combined with subsequent thermal oxidation. The 3D porous Cu structure was completely transformed to Cu2O with 220℃ annealing, which exhibited high electrochemical specific surface area and good photocatalytic CO2 reduction performance. Compared with non-porous Cu2O structure, 3D porous Cu2O demonstrated 2.5 times increment of concentration of photogenerated carriers (4.3 × 1020 cm−3) and 24-fold enhancement of photocatalytic CO2 reduction to CO (13.4 nmol cm-2h−1). Especially, some C2 reduction product was observed for the 3D porous structure. This is because the 3D porous structure improves the mass transfer efficiency of CO2 gas, and the nano-sized dendrite structure enhances the efficiency of light capture and photoinduced electron transportation. Furthermore, the rapid separation and high reaction activity of photoinduced holes and electrons result in the anti-photocorrosion properties of 3D porous Cu2O. Therefore, this work not only provides new idea to address the activity and stability of Cu2O, but also develops a facile strategy for photocatalytic reduction of CO2.