Mo-modified silicon nitride enables efficient CO2 photocatalytic reduction

Mo introduction significantly enhances CO 2 adsorption and visible-light harvesting. • MSN2 achieves a CO production rate of 15.95 μmol g −1 h −1 with 99% selectivity. • Mo-induced active sites promote charge separation and accelerate CO 2 activation. • DFT calculations reveal the critical role of Mo sites in lowering CO 2 reduction barriers. Photocatalytic CO 2 reduction provides a promising strategy for carbon resource utilization and solar-to-chemical energy conversion. However, achieving highly efficient and selective CO 2 conversion remains challenging due to the intrinsically stable CO 2 molecules, rapid recombination of photogenerated charge carriers, and competing reaction pathways. Herein, a series of Mo-modified silicon nitride (MSN) photocatalysts were constructed through a facile calcination strategy, enabling synergistic regulation of electronic structure, surface active sites, and CO 2 adsorption capability. The optimized MSN2 catalyst exhibits outstanding photocatalytic CO 2 reduction activity, under simulated solar irradiation, the CO evolution rate reaches a maximum of 15.95 μmol·g −1 ·h −1 , which is significantly higher than that of pristine Si 3 N 4 , accompanied by an ultrahigh CO selectivity of 99%. Comprehensive characterization shows that Mo introduction induces lattice distortion and surface active sites, thereby enhancing visible-light absorption. In situ FTIR spectroscopy and density functional theory calculations further reveal that Mo-associated surface active sites serve as highly active centers for CO 2 activation by stabilizing key intermediates and lowering the free-energy barrier for CO formation. This work and electronic modulation in Mo-modified silicon nitride and offers a rational design strategy for developing efficient and selective low-cost photocatalysts for solar-driven CO 2 conversion.