Hydriding Pd cocatalysts: An approach to giant enhancement on photocatalytic CO2 reduction into CH4

Photocatalytic reduction of CO 2 into high value-added CH 4 is a promising solution for energy and environmental crises. Integrating semiconductors with cocatalysts can improve the activities for photocatalytic CO 2 reduction; however, most metal cocatalysts mainly produce CO and H 2 . Herein, we report a cocatalyst hydridation approach for significantly enhancing the photocatalytic reduction of CO 2 into CH 4 . Hydriding Pd cocatalysts into PdH 0.43 played a dual role in performance enhancement. As revealed by our isotopic labeling experiments, the PdH 0.43 hydride cocatalysts reduced H 2 evolution, which suppressed the H 2 production and facilitated the conversion of the CO intermediate into the final product: CH 4 . Meanwhile, hydridation promoted the electron trapping on the cocatalysts, improving the charge separation. This approach increased the photocatalytic selectivity in CH 4 production from 3.2% to 63.6% on Pd{100} and from 15.6% to 73.4% on Pd{111}. The results provide insights into photocatalytic mechanism studies and introduce new opportunities for designing materials towards photocatalytic CO 2 conversion.