Nb-Doping Induced Structure Modulation and Synergistic Active Sites in W₁₈O₄₉ to Enhance Methane Photosynthesis

Solar-powered conversion of CO₂ and H₂O into renewable fuels represents a promising technology for achieving carbon neutrality, while still remains considerable challenges because it involves a complex multistep electron-proton transfer mechanism including both CO₂ reduction and H₂O oxidation. The establishment of synergistic redox active sites, along with a comprehensive understanding of the photocatalytic mechanism, is highly imperative. Herein, we developed a Nb-doped W₁₈O₄₉ photocatalyst which features synergistic Nb⁵⁺-W^δ+ active sites and exhibits efficient light absorption across the entire solar spectrum. This photocatalyst demonstrated outstanding photocatalytic performance in CO₂ and H₂O conversion under simulated sunlight, achieving a CH₄ evolution rate of 20.27 μmol·gcat^-1·h^-1 with a selectivity of 82.6%. The Nb dopant introduces efficient active sites that synergistically interact with W^δ+ sites to enhance CO₂ reduction and facilitate H₂O oxidation for proton provision, thereby accelerating the whole reaction process by balancing the two half-reactions in kinetics. Moreover, the plasmon-induced infrared absorption results in a significant temperature increase, further accelerating the photocatalytic reaction. Key intermediates involved in the formation of CH₄ are monitored using in situ infrared spectroscopy, providing evidence for the understanding of CO₂ photoreduction mechanism. This study offers a novel perspective on designing efficient catalysts for artificial photosynthesis by constructing synergistic active sites to simultaneously promote CO₂ and H₂O conversion.