Ultrathin NCDs/BiOBr with oxygen vacancies for efficient photocatalytic degradation of tetracyclines: Revealing the triple role of NCDs in the synthesis

Photocatalytic degradation of organic pollutants is a widely used technology. Constructing oxygen vacancies, compounding other materials, and adjusting semiconductor morphology are effective ways to promote the performance of photocatalysis. In this study, ultrathin NCDs/BiOBr nanosheets with excellent photocatalytic ability were prepared. The triple role of NCDs in NCDs/BiOBr synthesis was revealed: controlling the thickness of the nanosheets, increasing the oxygen vacancy concentration, and regulating the band gap structure. Rhodamine B and tetracycline were degraded by the samples in visible light to examine their photocatalytic properties. The samples with the highest electron transfer efficiency were verified by optical and electrochemical characterization. As-synthesized NCDs/BiOBr catalysts exhibited good degradation in different water samples，indicating the ability of the samples for practical applications. In addition, the intermediates and possible degradation pathways of the prepared catalysts for the degradation of TC processes were also analyzed in depth. The electron transfer pathway and photocatalytic mechanism of NCDs/BiOBr were proposed in combination with free radical detection and energy band calculation.