Boosted Scavenger-Free Overall Nitrogen Photofixation with Molybdenum Incorporated Bismuth-Rich Oxychlorides

The design of highly efficient photocatalysts to photoreduce nitrogen (N2) to ammonia (NH3) under mild conditions is extremely challenging. In this work, various molar ratio of molybdenum (Mo) is incorporated into Bi12O17Cl2 via a hydrothermal process. The resulting Mo-doped Bi12O17Cl2 exhibits remarkable solar-driven activity for N2 photo fixation without any scavengers or sacrificial agents. The optimal sample with 5% Mo dopants displays an NH3 yield of 39.83 µmol g-1 h-1, a 1.6-fold improvement over undoped pristine Bi12O17Cl2. The impressive performance is attributed to the synergistic effects of oxygen vacancies (OVs) and Mo-loading, enhancing light absorption and extending photo-response through band gap reduction. Additional contributions arise from the enriched active sites, facilitating N2 adsorption and electron transport to the reactants. Density functional theory calculations reveal that Mo integration induces significant charge redistribution around the active sites, thereby reducing the energy barrier associated with N2 activation and protonation. In-depth investigation into the reaction pathway unravels the step-by-step reaction process which further elucidates the beneficial role of Mo loading in the overall N2 photoconversion process. As a whole, this work promotes a simple and effective engineering approach based on heteroatom doping as an efficacious strategy to design highly active photocatalysts toward N2 photo fixation.