Z-Scheme Direct Dual Semiconductor Photocatalytic System with Porous g-C3N4/Fe2(MoO4)3 Composite: A Promising Approach for Enhanced Photocatalytic Degradation of Doxycycline

Photocatalytic removal of antibiotic pollutants is a promising technology for advancing society. However, quick charge recombination in semiconductors hinders the effectiveness of photocatalysis. The construction of a heterojunction photocatalyst is an effective approach to improving the degradation rate. In this present work, 2D porous graphitic carbon nitride (denoted as PCN) nanosheets were prepared through a salt-assisted thermal decomposition method. Subsequently, a novel porous g-C3N4/Fe2(MoO4)3 (denoted as PCN/FMO) composite was designed using a facile hydrothermal process for the degradation of doxycycline (DOX). The formation of Z-scheme heterojunctions and chemically bonded interfacial charge transfer effects in the PCN/FMO composite facilitated the efficient charge carrier separation and migration. As a result, the enhanced photocatalytic degradation efficiency of the PCN/FMO composite reached 92.1% and K value 0.0207 min−1 after 120 min of visible light irradiation, which is comparatively higher than that of pristine CN (32.71% and 0.0031 min−1), PCN (45.1% and 0.0047 min−1), and FMO (52.9% and 0.0062 min−1) photocatalysts, and there is no substantial reduction in DOX degradation performance after six cycles. Active species trapping analysis identified the primary reactive agents, suggesting that h+, •OH, and •O2− radicals are the predominant reactive species in the photocatalytic degradation process. The findings of this work suggest that the as-prepared PCN/FMO composite is a promising candidate for highly efficient degradation of wastewater containing antibiotic pollutants.