Persulfate-aided modified graphitic carbon nitride-based photocatalysts for wastewater treatment: synergistic mechanism

The metal-free graphitic carbon nitride (GCN) has ignited research in the realm of sulfate radical-based AOPs for aqueous pollutant degradation owing to the tunable optoelectronic properties. Upon light irradiations, the electronic excitations in GCN cause peroxo (O-O) bond cleavage in peroxydimonosulfate (PDS) and peroxymonosulfate (PMS) oxidants to release SO4 − and ·OH reactive oxidative species. The SO4 − radicals benefited from higher oxidation potential (2.5–3.1V), longer half-life period (4×10−5s), and responsiveness in the pH range. The synergistic mechanism of GCN-mediated PS/PMS photoactivation confirms the generation of ·OH to overcome the poor reductive potential of GCN and fastens the degradation rate of the reaction. With the advancement in surface modification strategies, researchers have explored the methods of introducing functional groups for increasing the surface-active sites to activate PMS/PDS over GCN.