CuO/Ag/UiO-66 catalysts were applied in photocatalytic CO₂ reduction, and the optimal catalyst exhibited superior selectivity of HCOOH as high as 95.9%. The reasons for the high selectivity were investigated in depth, especially the effect of Ag cocatalyst. Z-scheme heterojunction was formed between CuO and UiO-66, with Ag as the bridge to promote the charge transfer and separation. The in-situ FT-IR and theoretical calculation results confirmed that CuO is the real site for activation of CO₂, while Ag nanoparticles possess strong adsorption capacity for *H protons, which is conducive to the combination of *H with adsorbed *OCO on adjacent CuO to form *OCOH intermediates and generate HCOOH subsequently. This result validated that Ag could promote the generation of two-electron reduction products by controlling the reaction intermediates and the degree of CO₂ reduction, and might provide a universal approach to achieve the regulation of product selectivity of photocatalytic CO₂ reduction.

将CuO/Ag/UiO-66催化剂应用于光催化CO ₂还原，最佳催化剂对HCOOH的选择性高达95.9%。深入研究了高选择性的原因，特别是Ag助催化剂的作用。CuO和UiO-66之间形成Z型异质结，以Ag为桥促进电荷转移和分离。原位FT-IR和理论计算结果证实CuO是CO _{2活化的真实位点}，而Ag纳米粒子对*H质子具有很强的吸附能力，有利于*H与相邻CuO上吸附的*OCO结合形成*OCOH中间体，随后生成HCOOH。_{该结果验证了Ag可以通过控制反应中间体和CO 2}还原程度来促进双电子还原产物的生成，为实现光催化CO ₂还原产物选择性调控提供了一种通用的途径。