Origin of the Boosting Effect of Polyoxometalates in Photocatalysis: The Case of CO₂ Reduction by a Rh-Containing Metal–Organic Framework

The immobilization of polyoxometalates (POMs) near catalytic centers metal–organic frameworks (MOFs) has been reported as an advantageous strategy to boost their photocatalytic activity toward strategic reactions such CO2 reduction (CO2RR) or hydrogen evolution (HER), although the reasons for enhancement are still poorly understood. Unveiling role POM guests in reaction mechanisms is therefore a key step development next generation multicomponent materials with optimal performances. Here, we elucidate remarkable encapsulated [PW12O40]3– (PW12) boosting Rh-functionalized UiO-67 MOF CO2RR and HER by combining theoretical density functional theory microkinetic modeling approaches experimental photophysical spectroscopic techniques. First, characterized detail mechanism catalyzed PW12-containing MOF, using [Ru(bpy)3]2+ photosensitizer (PS) triethanolamine (TEOA) sacrificial electron donor acetonitrile. Our results reveal that POMs act efficient reservoirs, which quench [Ru(bpy)3]+?the photogenerated reduced form PS?and transfer electrons Rh sites MOF. Notably, this shown favor regeneration oxidized PS over its unproductive degradation, turnover numbers system. Such can explain not only higher formate H2 product yields POM-containing catalyst but also experimentally observed impact on pathway than one, source protons generated reductive quenching photoexcited TEOA. Finally, our computational exploration was extended whole variety POMs, allowed establishing relationships between redox potentials related materials. reached when both ability accept reduce simultaneously maximized, leading volcano plot whereby moderate potential display highest