Efficient photocatalytic conversion of CO ₂ to acetic acid using a composite catalyst

Transforming CO₂ into high-value chemicals is crucial for combating the rising threats of global warming and energy-related problems. The selective generation of C2 or C2+ products <i>via</i> CO₂ photoreduction is a complex endeavor, largely hindered by the sluggish kinetics of C-C bond formation. We highlight the potential of incorporating silver nanoparticles (Ag NPs) into the metal-organic framework (MOF) NU-1000-SH, which can harness light energy and promote efficient electron transfer. The local structure of silver nanoparticles on thiol-functionalized NU-1000 was studied utilizing atomic pair distribution function (PDF) analysis. The selective C2 product, acetic acid, is produced by Ag@NU-1000-SH under white light (30 W) without the use of sacrificial agents. The product analysis was confirmed by NMR, HRMS, and ¹³CO₂ labelling experiments. The catalyst demonstrated a good acetate yield of 280.0 μmol g^-1 h^-1, with a selectivity rate of 78.48%. The findings from XPS and DFT calculations indicate that the charge-polarized states in the as-synthesized catalyst act as asymmetric centers that enhance the C-C coupling reaction. This observation is pivotal for advancing our knowledge of catalytic behavior. Additionally, the integration of experimental techniques, such as <i>in situ</i> DRIFT studies, with theoretical models provides a comprehensive understanding of the C-C coupling mechanism involving COOH* intermediates.