Construction of S-type TiO2/CoPc heterojunction and photocatalytic degradation of tetracycline

Semiconductor photocatalysis is an effective strategy for solving environmental pollution problems. TiO2 is one of the most widely used semiconductors. However, the wider bandgap and the fast complexation of carriers constrain its practical application. The above problems can be solved effectively by constructing heterojunctions. Herein, S-type TiO2/CoPc heterojunction was obtained by in situ complexation with cobalt phthalocyanine(CoPc),and the matched energy band structure of the two enabled the effective separation of photogenerated carriers. Meanwhile, the metal Co ion centre could activate peroxymonosulfate(PMS). The results of photocatalytic experiments showed that the TiO2/CoPc heterojunction+PMS could achieve 72% degradation of tetracycline hydrochloride(TC) by irradiating under visible light for 60 min. Compared with TiO2+PMS, the reaction rate was increased by 11 times. The excellent photocatalytic performance may be attributed to the improved Co2+/Co3+ cycling by photogenerated electrons, and the synergistic effect of efficient carrier separation and Co2+/Co3+ cycling in the heterojunction achieved the efficient degradation of TC.