In-Situ Real-Time Detection of Active Sites in Indium-based MOFs for Light-Driven CO2 Reduction by X-ray Absorption

The photocatalytic reduction of CO₂ into valuable fuels and chemicals, such as CO and CH₄, presents a promising solution to both energy demands and environmental challenges. This study utilizes ligand engineering to precisely tailor the band structure of Indium-based Metal-Organic Frameworks (MIL-68-X, where X = NH₂, H, NO₂). The primary objective is to identify the nature of catalytic active sites under operational conditions, specifically focusing on the electronic states and coordination geometries of In-oxo sites at the Indium K-edge, both in darkness and under illumination, within the reactant feed stream. We aim to pinpoint the active sites and understand the evolution of In-oxo active sites—including their coordination and oxidation states—in response to changing reaction conditions and under steady-state conditions. Additionally, we will investigate the electronic states (e.g., In³⁺ or In⁺) and coordination numbers of metal-metal and metal-ligand interactions involving Indium.