Nanodiamonds anchored on porous ZnSnO3 cubes as an efficient composite photocatalyst with improved visible-light photocatalytic degradation of tetracycline

Abstract Using sunlight to degrade organic pollutants is a promising and environmentally friendly wastewater treatment strategy. Herein, nanodiamonds (NDs) anchored on ZnSnO3 (ZSO) cubes to form NDs/ZSO composite photocatalyst was successfully prepared via one-step calcination route. Analysis of experimental and characterization results shows that the NDs are uniformly dispersed on the surface of the ZSO cubes to form the stable heterojunction, which not only increases the light absorption, but also promotes the separation of photogenerated electrons and holes, thus improving the photocatalytic performance. In addition, the contact angle test demonstrates that the introduction of NDs with oxygen-containing functional groups is helpful to promote the hydrophilicity of ZSO, and then to improve the contact probability of organic pollutants and enhance photocatalytic degradation activity. The optimal 4% NDs/ZSO composite displays the first-rank photocatalytic efficiency in tetracycline (TC) degradation under visible light and the degradation rate is up to 90%, which is 4.73 times higher than pristine ZSO. Furthermore, the active species capture experiments and electron spin resonance (ESR) techniques were adopted to investigate the photocatalytic reaction mechanism. Liquid chromatography-mass spectrometry (LC-MS) was employed to analyze the degradation intermediate products in photocatalytic process. This study provides a simple strategy for the preparation of highly efficient and stable NDs-based composite photocatalysts.