Comparative study of the photocatalytic activity of g‐C3N4/MN4 (M = Mn, Fe, Co) for water splitting reaction: A theoretical study

Abstract In this study, nanocomposites of g‐C 3 N 4 /MN 4 (where M is Mn, Fe and Co) have been designed using advanced density functional theory (DFT) calculations. A comprehensive analysis was conducted on the geometry, electronic, optical properties, work function, charge transfer interaction and adhesion energy of the g‐C 3 N 4 /MN 4 heterostructures and concluded that g‐C 3 N 4 /FeN 4 and g‐C 3 N 4 /CoN 4 heterojunctions exhibit higher photocatalytic performance than individual units. The better photocatalytic activity can be attributed mainly by two facts; (i) the visible light absorption of both g‐C 3 N 4 /FeN 4 and g‐C 3 N 4 /CoN 4 interfaces are higher compared to its isolated analogs and (ii) a significant enhancement of band gap energy in g‐C 3 N 4 /FeN 4 and g‐C 3 N 4 /CoN 4 heterostructures limited the electron–hole recombination significantly. The potential of the g‐C 3 N 4 /MN 4 heterojunctions as a photocatalyst for the water splitting reaction was assessed by examining its band alignment for water splitting reaction. Importantly, while the electronic and magnetic properties of MN 4 systems were studied, this is the first example of inclusion of MN 4 on graphene‐based material (g‐C 3 N 4 ) for studying the photocatalytic activity. The state of the art DFT calculations emphasis that g‐C 3 N 4 /FeN 4 and g‐C 3 N 4 /CoN 4 heterojunctions are half metallic photocatalysts, which is limited till date.