An innovative CuxAg50−x/UiO66-NH2 photocatalyst prepared using a dual ship bottling strategy for photocatalytic CO2 reduction: controlled product selectivity and pathways

Abstract

Photocatalytic CO₂ reduction technology is one of the most promising solutions to solve the greenhouse effect and global energy crisis. However, its low conversion efficiency and poor product selectivity greatly limit the practical application of this technology. This study innovatively proposed a “dual ship bottling” strategy to prepare a Cu_xAg_50−x/UiO66-NH₂ catalyst for the photocatalytic CO₂ reduction reaction (CO₂RR). Many individual Cu_xAg_50−x alloys were successfully encapsulated within UiO66-NH₂, and the nano-confinement effect of UiO66-NH₂ effectively prevented the aggregation of Cu_xAg_50−x alloys, thereby significantly improving the catalytic activity of Cu_xAg_50−x/UiO66-NH₂. The Cu_xAg_50−x/UiO66-NH₂ photocatalytic system with different Cu : Ag molar ratios exhibited astonishing yields (38.64–162.47 μmol g⁻¹ h⁻¹) of reduced carbon products, excellent cycling stability and long-term durability exceeding 30 h, as well as the corresponding selectivity for C₂–(C₂H₄, C₂H₅OH), C₁–(CH₄, CH₃OH), C₁–(CO) was 91.67%, 96.25% and 93.01%, respectively. Under visible light irradiation, some photogenerated electrons were transferred from UiO66-NH₂ to Cu_xAg_50−x alloys. The different bonding strengths between Cu–Ag catalytic active sites in Cu_xAg_50−x alloys and *CO intermediates determined the three subsequent reaction pathways of *CO (*CO → α, α = *COCO, *CHO and CO). In addition, Cu_xAg_50−x/UiO66-NH₂ exhibited strong adsorption of *H intermediates, effectively inhibiting the hydrogen evolution reaction (HER). Finally, the regulation mechanism of Cu_xAg_50−x/UiO66-NH₂ for the photocatalytic CO₂RR was revealed. This study provides a new insight into the design of new photocatalysts and selective regulation of reduced carbon products.