Facile fabrication of a Z-scheme PVA/gelatin based CeO2/g-C3N4 heterojunction aerogel for enhanced visible light mediated photocatalytic degradation of psychoactive drug in aqueous phase

Abstract

With rapid industrialization and escalating urbanism, the accumulation of pharmaceutically active substances and their toxic byproducts have become a global environmental burden. To address this concern, herein, a self-supporting porous PVA/gelatin-based cerium dioxide (CeO₂)/graphitic carbon nitride (g-C₃N₄) (pg-CCN) aerogel photocatalyst is synthesized through a facile two-step approach. The resulting lightweight aerogel is systematically evaluated for its ability to degrade caffeine (CAF), a psychoactive drug through visible light-mediated photocatalysis. The optimised pg-CCN aerogel manifests outstanding photocatalytic degradation efficiency of 95.8 % towards CAF within 180 min of visible light irradiation. This is apparently due to the heterostructure offering increased specific surface area, interconnected porous network, moderate band gap, fast interfacial charge transfer kinetics, and lowered recombination rate of photogenerated charge carriers. The latter is also because of a direct Z-scheme mechanism of action of the as-synthesized pg-CCN heterojunction. For a more comprehensive assessment of the photocatalytic efficiency of pg-CCN aerogel from a practical standpoint, investigations were conducted on the removal of other coexisting pharmaceuticals from complex multicomponent systems in various real water matrices. Further, these self-supporting aerogels not only exhibit high reusability with easy retrieval but also do not undergo any structural deformation on repeated usage. The findings of this work proffer valuable insights into the development of extremely efficacious Z-scheme heterojunction photocatalysts for the degradation of refractory pollutants.