Nitrogen-doped ultrathin graphene encapsulated Cu nanoparticles decorated on SrTiO3 as an efficient water oxidation photocatalyst with activity comparable to BiVO4 under visible-light irradiation

Water oxidation is known as the bottleneck for both natural and artificial photosynthesis, and is still facing challenges in developing visible-light responsive photocatalyst with promoted efficiency. Herein, Cu nanoparticle encapsulated in nitrogen-doped ultrathin graphene (NC) layer decorated on SrTiO3 (STO) is designed as a high-efficient, low-cost photocatalyst for the photocatalytic water oxidation under visible-light irradiation. The O-2 evolution rate over 1% Cu@NC/STO is approximately 2 times that of commercial WO3, and even comparable to BiVO4. Systematical studies and density functional theory simulations show that nitrogen-doped graphene layer not only protects Cu NPs from oxidation, but also modifies the electronic states of carbon layer in addition to enhancing charge carriers separation, which ultimately promotes photocatalytic water oxidation with reduced apparent activation energy. Furthermore, in universality test, Cu@NC/STO showed an excellent activity for thermocatalytic reduction of 4-nitrophenol. This work demonstrated the prospect of rational designing Cu-based photocatalysts with high stability and efficiency.