Steering Multistep Charge Transfer for Highly Selectively Photocatalytic Reduction of CO2 into CH4 over Pd/Cu2O/TiO2 Ternary Hybrid

Abstract

Due to the low charge separation efficiency and high stability of the CO2 molecule, photoreduction of CO2 into a single multielectron product such as CH4 with a simultaneous high conversion rate and selectivity is challenging. Therefore, it is highly desirable to accelerate charge separation and transfer and provide an electron‐enriched catalyst surface for the deep reduction of CO2. Herein, a Pd/Cu2O/TiO2 ternary hybrid photocatalyst consisting of Pd nanoparticles (NPs) and Cu2O NPs‐decorated TiO2 nanosheets is rationally designed, and highly selective photocatalytic photoreduction of CO2 into CH4 is achieved. The Pd/Cu2O/TiO2 photocatalyst shows a high CH4 production rate of 42.8 μmol g−1 h−1 with an extremely high selectivity of 99.5%. This CH4 production rate is 61.1, 5.4, and 2.8 times higher than the bare TiO2, Cu2O/TiO2, and Pd/TiO2, respectively. In this Pd/Cu2O/TiO2 hybrid, a consecutive multistep charge transfer is steered between the Cu2O/TiO2 heterojunction and Pd, ensures accelerated charge separation and transfer, and leads to the formation of a spatially separated electron‐enriched surface (Pd) and hole‐enriched surface (Cu2O). This spatially oriented charge transfer and the charge‐enriched catalyst surface synergistically contribute to the simultaneous high conversion rate and selectivity of CH4.