Photocatalytic reduction of CO₂ into high value-added CH₄ is a promising solution for energy and environmental crises. Integrating semiconductors with cocatalysts can improve the activities for photocatalytic CO₂ reduction; however, most metal cocatalysts mainly produce CO and H₂. Herein, we report a cocatalyst hydridation approach for significantly enhancing the photocatalytic reduction of CO₂ into CH₄. 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 H₂ evolution, which suppressed the H₂ production and facilitated the conversion of the CO intermediate into the final product: CH₄. Meanwhile, hydridation promoted the electron trapping on the cocatalysts, improving the charge separation. This approach increased the photocatalytic selectivity in CH₄ 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 CO₂ conversion.

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将CO ₂光催化还原成高附加值的CH ₄是解决能源和环境危机的有前途的解决方案。半导体与助催化剂的结合可以提高光催化还原CO ₂的活性；但是，大多数金属助催化剂主要产生CO和H ₂。在本文中，我们报告了一种助催化剂氢化方法，可显着增强将CO ₂转化为CH ₄的光催化还原作用。将Pd助催化剂氢化成PdH _0.43在提高性能方面起着双重作用。正如我们的同位素标记实验所揭示的那样，PdH _0.43氢化物助催化剂还原了H ₂气体的释放，抑制了H _2的产生并促进了CO中间体向最终产物CH ₄的转化。同时，氢化促进了电子在助催化剂上的俘获，从而改善了电荷分离。这种方法将CH ₄生产中的光催化选择性从Pd {100}上的3.2％提高到63.6％，并将Pd {111}上的从15.6％提高到73.4％。结果为光催化机理研究提供了见识，并为设计用于光催化CO ₂转化的材料提供了新的机会。

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