An overview on photocatalytic sulfate radical formation via doped graphitic carbon nitride for water remediation

The photoactivated sulfate radicals have brought new impetus in organic pollutant degradation mainly benefitting from higher oxidation potential of 2.5–3.1 V, longer half-life period (4 × 10−5 s), and responsive in wider pH range. The synergistic mechanism of graphitic carbon nitride (GCN)-mediated persulfate/peroxymonosulfate (PS/PMS) photocatalytic activation ensures generation of hydroxyl radical to overcome the poor reductive potential of GCN and fastens the degradation reaction rate. The review elaborates doping of GCN to overcome the photocatalytic limitation of rapid charge-carrier recombination maneuvering the availability of photogenerated electrons in conduction of GCN responsible for photocatalytic activation of PS/PMS. In particular, the incorporation of dopant, that is, metals, nonmetals, or transition metals in GCN lattice, regulates the bandgap for extended visible-light absorption. The predominant challenges associated with the PS/PMS photocatalytic activation mechanism via 2D GCN-based photocatalysts are proposed.