Synergistic effect of internal electric field and ligand-to-metal charge transfer in Z-scheme CuPc/ZnIn2S4 for boosting photocatalytic hydrogen evolution

Abstract

The construction of an efficient and stable photocatalytic water splitting system is the critical path and arduous challenge to convert solar energy into green hydrogen energy. Herein, a novel CuPc/ZnIn2S4 organic–inorganic hybrid photocatalyst was designed and used for photocatalytic hydrogen production from water. The separation of photogenerated electrons and holes was greatly enhanced due to the formation of the compact organic–inorganic heterointerface and the Z-scheme charge transport mechanism between CuPc and ZnIn2S4. Meanwhile, CuPc can broaden the light absorption of CuPc/ZnIn2S4 to the near infrared region, which enhances the utilization of sunlight. Moreover, the Cu metal center of CuPc could serve as the electron acceptor to accumulate photogenerated electrons via the ligand-to-metal charge transfer pathway, which further accelerates the separation of photogenerated charge carriers and enhances the photocatalytic hydrogen production efficiency. The optimal CuPc/ZnIn2S4 photocatalyst exhibited a hydrogen production rate of 151.2 μmol h−1, which was 8.1 times higher than that of pristine ZnIn2S4 under visible light irradiation. This work provides an idea for the construction of an organic–inorganic photocatalytic system for solar hydrogen production.