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

Abstract

• Novel porous g-C 3 N 4 nanosheets were synthesised and characterized. • Porous g-C 3 N 4 nanosheets showed an enhanced efficiency on photodegradation of tetracycline under visible light irradiation. • The influence of catalyst mass, pH, tetracycline concentration and reusability were studied. • Investigations of ROS revealed that •O 2 − and h + are responsible for tetracycline degradation. • The photocatalytic mechanism of porous g-C 3 N 4 nanosheets was analysed. 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-C 3 N 4 nanosheets were synthesised via pyrocondensation polymerization with melamine and NH 4 HCO 3 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-C 3 N 4 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 (•O 2 − ) 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-C 3 N 4 to enhance its photocatalytic performance under visible light.

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