Bifunctional CoMn Oxyhydroxide Cocatalyst-Modified BiOCl toward Improved Photocatalytic Performance and Photostability

Photogenerated hole-mediated photocorrosion caused by excessive accumulation is an important limiting factor for the photocatalytic performance of BiOCl. In this work, a heterometallic oxyhydroxide (CoMnOOH) cocatalyst-modified BiOCl composite with a closely contacted interface was fabricated through an in situ photooxidation treatment procedure. The photocatalytic results indicate that the optimized CoMnOOH/BiOCl photocatalyst obtains exceptional tetracycline (TC) degradation efficiency (up to 92.12%) with a rate constant of 0.02423 min^-1 (7.15 times higher than that of pure BiOCl) under UV light irradiation. After five continuous cycles of experiments, CoMnOOH/BiOCl shows a negligible decline (7.8%) in photocatalytic performance, indicating good optical stability. The improved stability under illumination conditions can be ascribed to the fact that ultrathin CoMnOOH on the BiOCl surface not only greatly enhances the transport, separation, and surficial reaction rates of photogenerated holes but also provides profuse active sites for enhancing the photocatalytic reaction, thus inhibiting its photocorrosion. Furthermore, the results of control experiments and EPR spectra confirm that the ·O₂^- radical plays a vital role in the photocatalytic TC degradation procedure. The reliable bimetallic oxyhydroxide modification strategy can effectively mitigate photocorrosion and optimize photocatalytic performance, offering vital insights for an excellent photocatalytic material design.