Immobilization of bismuth oxychloride on cellulose nanocrystal for sunlight-driven superior photosensitized degradation.

Semiconductor photocatalysis is considered to be an important green technology for sewage treatment. However, most of the pollutant degradation studies used simulated sunlight in a laboratory, which has great energy cost with limited applications in industry. Herein, cellulose nanocrystal (CNC) with rich hydroxyl groups and high specific surface area are used as the matrix to construct composites with BiOCl, which improves the dispersibility with an increased number of oxygen vacancies on BiOCl. The obtained composite photocatalyst, i.e., BiOCl/CNC, showed an excellent performance with good recyclability. Within 30 min, 99% of RhB (20 mg/L) was degraded under simulated visible light and 94% under natural sunlight. The reaction system maintains excellent catalytic performance after being scaled up by 10×. Compared with reported BiOCl-based composites in literature, BiOCl/CNC had excellent photocatalytic activity for the RhB degradation with good recyclability. Subsequently, by identifying the active species, a reasonable photocatalytic mechanism was proposed for RhB degradation. This work developed an economical and effective visible light sensitive photocatalyst for the treatment of organic dyes in water.