Hot Interband Carrier Exploitation in a Ru/MOF Schottky Junction for Photocatalytic CO₂ Reduction

Visible light-driven photocatalytic reduction of CO₂ to value-added fuels and chemicals has attracted extensive interest for decades. However, the emerging photocatalysis paradigm through an interband transition in non-plasmonic metals remains challenging. Herein, a new strategy, namely hot carrier exploitation is demonstrated, for highly efficient CO₂ reduction through the interband transition in non-plasmonic Ru nanoparticles (NPs). The Ru NPs are integrated with a metal-organic framework (MOF) to construct a Schottky junction of Ru@MOF-808, which features a directed injection of hot interband electrons from Ru NPs to adsorbed substrates, and localized enrichment and activation of substrates around Ru catalytic centers, due to its high Schottky barrier, superior gas adsorption capacity, and excellent hydrogen spillover capability. Hot interband holes in Ru NPs can also be promptly quenched by enriched active H species, ensuring sustainable hot electron generation and producing abundant protons for CO₂ methanation. Such catalyst design enables highly efficient utilization of hot interband carriers, and in turn, substantially accelerates the kinetically challenging CO₂ methanation involving 8 electrons and 8 protons. Consequently, Ru@MOF-808 delivers a record-high apparent quantum yield of 17.16% under visible light and ambient conditions. The finding provides new insights into heterogeneous photocatalysis, and opens up a new avenue to efficient CO₂ utilization.