Tuning CO2 photoreduction: CoN/KPCN catalysts for High CH4 selectivity through an efficient microwave molten salt heating synthesis

Photocatalytic reduction of CO2 to CH4 holds promise for sustainable energy and CO2 mitigation. In this study, we present the rapid synthesis of efficient composite photocatalysts via a one-step microwave molten salt heating method. Typically, potassium ions (K+) are directionally doped into polymeric carbon nitride (PCN) interlayer cavities, while CoN nanoparticles selectively form on K-doped PCN (KPCN). CoN/KPCN catalysts exhibit exceptional photocatalytic performance, yielding 45.71 μmol g−1 h−1 CH4 with 98.18% selectivity under visible light illumination. This mainly results from the synergistic effect of the enhanced crystallinity, expanded light absorption, efficient charge transfer, superior CO2 adsorption, and enhanced carrier dynamics. More importantly, the introduction of K+ is in favor of the high CH4 photoreduction selectivity both in view of kinetically and thermodynamically. This study informs carbon nitride-based photocatalyst development and underscores the potential of CoN/KPCN as a catalyst for high CH4 selectivity in CO2 photoreduction, contributing to sustainable energy and environmental conservation.