Steering Multistep Charge Transfer for Highly Selectively Photocatalytic Reduction of CO2 into CH4 over Pd/Cu2O/TiO2 Ternary Hybrid
Due to the low charge separation efficiency and high stability of the CO 2 molecule, photoreduction of CO 2 into a single multielectron product such as CH 4 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 CO 2 . Herein, a Pd/Cu 2 O/TiO 2 ternary hybrid photocatalyst consisting of Pd nanoparticles (NPs) and Cu 2 O NPs-decorated TiO 2 nanosheets is rationally designed, and highly selective photocatalytic photoreduction of CO 2 into CH 4 is achieved. The Pd/Cu 2 O/TiO 2 photocatalyst shows a high CH 4 production rate of 42.8 μmol g −1 h −1 with an extremely high selectivity of 99.5%. This CH 4 production rate is 61.1, 5.4, and 2.8 times higher than the bare TiO 2 , Cu 2 O/TiO 2 , and Pd/TiO 2 , respectively. In this Pd/Cu 2 O/TiO 2 hybrid, a consecutive multistep charge transfer is steered between the Cu 2 O/TiO 2 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 (Cu 2 O). This spatially oriented charge transfer and the charge-enriched catalyst surface synergistically contribute to the simultaneous high conversion rate and selectivity of CH 4 .
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