Enhanced photocatalytic degradation of tetracycline hydrochloride over Cd-CdS@g-C3N4 under visible light irradiation

Abstract

Cadmium sulfide (CdS), known for its strong light absorption capability and narrow band gap, has been extensively employed in photocatalytic degradation of organic pollution. However, when be exposed to light, the surface lattice sulfur of CdS undergoes rapid oxidation due to photo-generated holes, resulting in significant photocorrosion. Therefore, enhancing the stability and suppressing the photocorrosion of catalyst are crucial. In this study, Cd metal-loaded Cd-CdS@g-C3N4 composite catalysts are developed. This design not only effectively mitigates the issue of CdS photocorrosion but also exhibits outstanding photocatalytic degradation performance. XRD analysis reveals that Cd-CdS exhibits stronger diffraction peaks compared to CdS, indicating enhanced crystallinity and catalyst stability. Utilizing Cd as a metallic mediator, a rapid charge transfer across the heterojunctions is facilitated, bestowing the catalyst with superior photocatalytic efficiency. Notably, Cd-CdS exhibited the best photocatalytic degradation performance when the mass ratio of Cd-CdS to g-C3N4 was 1:2. The composite catalytic degradation efficiency of tetracycline hydrochloride (20 g·L-1) by Cd-CdS@g-C3N4 after 20 minutes reached 86.3%, and this commendable degradation rate was maintained even after four cycles. This research provides a vital approach towards enhancing the stability of g-C3N4/CdS heterojunction photocatalysts.