Versatility of CoPcS in CoPcS/TiO2 for MB degradation: photosensitization, charge separation and oxygen activation

Abstract

In this report, a composite photocatalyst consisting of cobalt phthalocyanine sulfate (CoPcS) and TiO₂ was prepared by a facile synthesis. Careful characterizations and measurements indicate a covalent grafting of CoPcS onto TiO₂ through Ti–O–S linkages, acquiring an intimate heterojunction between TiO₂ and CoPcS. The obtained composite was evaluated for its photocatalytic activity toward the degradation of methyl blue (MB) under visible light irradiation. The evaluation showed a significantly enhanced degradation rate of MB by CoPcS/TiO₂. The improved photocatalytic performance of CoPcS/TiO₂ was attributed to the photosensitization of TiO₂ by CoPcS, charge separation by electron transfer at the interface of the heterojunction formed between CoPcS and TiO₂, and oxygen activation via CoPcS. A synergetic mechanism in improving the photocatalytic performance of TiO₂ by CoPcS was investigated.