Modulating the Selectivity of CO2 Photoreduction by Regulating the Location of PtCu in a UiO-66@ZnIn2S4 Core–Shell Nanoreactor

Abstract

Controlling product selectivity in CO₂ photoreduction remains a grand challenge, particularly when CH₃OH is the targeted product. Herein, we demonstrate a strategy for tuning the selectivity of core–shell-structured UiO-66@ZnIn₂S₄ (UiO/ZIS) in visible-light-driven catalytic reduction of CO₂ by regulating the location of PtCu cocatalysts. The PtCu nanoparticles are confined within the inner UiO-66 core to afford PtCu/UiO/ZIS, incorporated at the UiO-66/ZnIn₂S₄ heterointerface to form UiO/PtCu/ZIS, and anchored on the outer ZnIn₂S₄ surface to fabricate UiO/ZIS/PtCu. The primary CO₂ reduction products for PtCu/UiO/ZIS, UiO/PtCu/ZIS, and UiO/ZIS/PtCu are CO, CH₃OH, and CH₄, with selectivities of 52.1, 72.7, and 88.8%, respectively. Experimental and theoretical results demonstrate that the spatial position of PtCu affects both the charge separation efficiency and the H₂O oxidation rate in the ternary photocatalysts. This, in turn, influences the supply of electrons and protons to the active sites, leading to varying degrees of CO₂ hydrogenation and deoxygenation. Additionally, different PtCu positions also create distinct reactive sites and surrounding microenvironments, altering the energy barriers of key reaction steps and giving rise to diverse CO₂ reduction pathways. This work provides fresh hints for rationally controlling product selectivity in artificial photosynthesis through the precise regulation of cocatalyst placement within heterostructured photocatalysts.