Modulating the\nSelectivity of CO<sub>2</sub> Photoreduction\nby Regulating the Location of PtCu in a UiO-66@ZnIn<sub>2</sub>S<sub>4</sub> Core–Shell Nanoreactor

Controlling\nproduct selectivity in CO<sub>2</sub> photoreduction\nremains a grand challenge, particularly when CH<sub>3</sub>OH is the\ntargeted product. Herein, we demonstrate a strategy for tuning the\nselectivity of core–shell-structured UiO-66@ZnIn<sub>2</sub>S<sub>4</sub> (UiO/ZIS) in visible-light-driven catalytic reduction\nof CO<sub>2</sub> by regulating the location of PtCu cocatalysts.\nThe PtCu nanoparticles are confined within the inner UiO-66 core to\nafford PtCu/UiO/ZIS, incorporated at the UiO-66/ZnIn<sub>2</sub>S<sub>4</sub> heterointerface to form UiO/PtCu/ZIS, and anchored on the\nouter ZnIn<sub>2</sub>S<sub>4</sub> surface to fabricate UiO/ZIS/PtCu.\nThe primary CO<sub>2</sub> reduction products for PtCu/UiO/ZIS, UiO/PtCu/ZIS,\nand UiO/ZIS/PtCu are CO, CH<sub>3</sub>OH, and CH<sub>4</sub>, with\nselectivities of 52.1, 72.7, and 88.8%, respectively. Experimental\nand theoretical results demonstrate that the spatial position of PtCu\naffects both the charge separation efficiency and the H<sub>2</sub>O oxidation rate in the ternary photocatalysts. This, in turn, influences\nthe supply of electrons and protons to the active sites, leading to\nvarying degrees of CO<sub>2</sub> hydrogenation and deoxygenation.\nAdditionally, different PtCu positions also create distinct reactive\nsites and surrounding microenvironments, altering the energy barriers\nof key reaction steps and giving rise to diverse CO<sub>2</sub> reduction\npathways. This work provides fresh hints for rationally controlling\nproduct selectivity in artificial photosynthesis through the precise\nregulation of cocatalyst placement within heterostructured photocatalysts.