Enhanced photodegradation of tetracycline by novel porous g-C3N4 nanosheets under visible light irradiation

Harnessing photocatalysis to degrade recalcitrant organic pollutants is a potent solution to addressing water pollution and alleviating energy crisis. Photocatalysts possessing intriguing characteristics such as controllable band gap, efficient visible-light absorption and high photocatalytic activity play a pivotal role in this regard. Herein, porous g-C3N4 nanosheets were synthesised via pyrocondensation polymerization with melamine and NH4HCO3 and their photocatalytic performance was investigated for degradation of tetracycline. Characterization techniques including XRD, FTIR, SEM, TEM, BET and UV-Vis spectroscopy were employed and revealed that porous g-C3N4 nanosheets increased light absorption capacity, provided more reactive sites and suppressed recombination of photogenerated electron-hole pairs, thus enhancing the material's photodegradation efficiency in the degradation of tetracycline. Optimization studies showed that 83 % of tetracycline was removed after 2 h of visible light irradiation using 1 gL- 1 catalyst loading, an initial concentration of 10 ppm and a solution pH of 7. The catalyst showed remarkable recyclability, retaining its chemical structure and functional properties, with 68 % degradation achieved after 5 cycles. Through radical scavenging experiments, superoxide radicals (center dot O2- ) and photogenerated hole (h+) were identified as the primary active species responsible for TC degradation. A plausible photocatalytic mechanism was proposed from these experiments. This study provides a facile, cost effective, eco-conscious and effective approach for incorporating porous hierarchical and 2D nanosheets morphology on g-C3N4 to enhance its photocatalytic performance under visible light.