2D/2D V2C mediated porous g-C3N4 heterojunction with the role of monolayer/multilayer MAX/MXene structures for stimulating photocatalytic CO2 reduction to fuels

2D vanadium carbide (V 2 C) MXene nanosheets coupled 2D porous g-C 3 N 4 (PCN) was designed and tested for photocatalytic CO 2 reduction under visible light. Controlled coupling g-C 3 N 4 with V 2 C MXene resulted in higher visible light absorption and efficient charge separation. Comparatively, V 2 C MXene found more favorable than V 2 AlC MAX due to more proficient charge separation. Highest performance was achieved with optimized 15%-V 2 C/g-C 3 N 4 , in which CO and CH 4 generation rates of 151 and 205 µmol g −1 , respectively, were attained. This enhancement was significantly higher than using V 2 AlC/g-C 3 N 4 and pure g-C 3 N 4 samples due to higher conductivity and large CO 2 adsorption capacity. The performance of V 2 C/g-C 3 N 4 composite was further examined under a variety of conditions such as pressure, catalyst loading, and reducing agents. With increasing pressure, higher yield of CO and CH 4 was attained due to increased reactant adhesion to the catalyst surface, whereas increasing catalyst loading has adverse effects. Water was the best reducing agent for CO evolution, while the methanol–water system enhanced CH 4 generation. Furthermore, the stability of composite lasted for several cycles without showing any obvious deterioration. The potential outcomes are assigned to a porous structure with intimate contact, effective charge carrier separation and porous 2D g-C 3 N 4 transporting electrons towards MXene surface. This study shows that 2D V 2 C MXene could be a potential carrier for constructing 2D/2D heterojunctions in photocatalytic CO 2 reduction to produce useful solar fuel. • 2D/2D V 2 C/ g-C 3 N 4 nanosheets heterojunction developed for CO 2 reduction to fuels. • V 2 C MXene is more effective for charge transport and segregation than the V 2 AlC MAX. • V 2 C MXene/g-C 3 N 4 efficiency was 6.8 times more than g-C 3 N 4 under solar energy. • Reducing agents contributed significantly to the reduction of CO 2 to CH 4 and CO. • Using 2D V 2 C with a g-C 3 N 4 photocatalyst, high cycle stability was achieved.