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

Abstract

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 (•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.