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+-Wδ+ 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 Wδ+ 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.