In-situ constructed Z-scheme Bi2O2CO3/g-C3N4 heterojunction: enhanced photocatalytic degradation of preservatives

With the increasing demand for preservatives in industries such as food, cosmetics, and pharmaceuticals, the environmental pollution associated with these compounds has attracted growing concern. Although preservatives are widely applied across diverse sectors, their environmental persistence and degradation behavior remain underexplored. In this study, a novel Z -scheme g-C 3 N 4 /Bi 2 O 2 CO 3 photocatalyst was synthesized, and two commonly used preservatives—potassium sorbate (PS) and methyl para-hydroxybenzoate (MPB)—were selected as model pollutants to systematically investigate the photocatalytic performance of the prepared composite. The results demonstrated that the g-C 3 N 4 /Bi 2 O 2 CO 3 heterostructure exhibited remarkable photocatalytic activity under UV light irradiation, achieving degradation efficiencies exceeding 98 % within 40 min. Furthermore, characterization tests and density functional theoretical (DFT) calculations jointly confirmed that the g-C 3 N 4 /Bi 2 O 2 CO 3 heterojunction follows a typical Z -scheme charge transfer mechanism. This Z-scheme configuration allows the photocatalyst to retain strong redox potentials, thereby improving its overall redox capability and photocatalytic efficiency. Meanwhile, Liquid Chromatograph Mass Spectrometer (LC-MS) analysis combined with toxicity assessment experiments proved the effectiveness and safety of g-C 3 N 4 /Bi 2 O 2 CO 3 in degrading preservatives. These findings offer a promising strategy for the design of high-performance Z -scheme heterojunction photocatalysts for the efficient degradation of environmental contaminants such as preservatives.