Covalently grafting porphyrin on SnO2 nanorods for hydrogen evolution and tetracycline hydrochloride removal from real pharmaceutical wastewater with significantly improved efficiency

Abstract

The sensitization of a wide-gap oxide semiconductor with a strong visible-light-absorbing porphyrin has been evidenced as a promising approach to craft highly efficient photocatalysts towards photocatalytic hydrogen evolution and environmental remediation. However, the practical utilization of porphyrins-sensitized oxide catalysts relies on the integration mode between porphyrins and metal oxide. Herein, a novel high-performance porphyrin-sensitized oxide catalyst is constructed via covalent assembling of copper porphyrin derivative of 5-(4-azidophenyl)-10,15,20-triaminoporphyrin (CuTPP–N3) on SnO2 nanorods by click reaction for the first time. The optimized 10 %CuTPP-N3/SnO2 hybrid demonstrates remarkably enhanced photocatalytic activity in H2 evolution of 658.6 μmol g−1h−1. It is almost 78 times higher than that of pristine SnO2. It also exhibits great potential for eliminating tetracycline hydrochloride (TCH) from various aqueous solutions with high durability under visible-light irradiation. Its removal rates in deionized water, tap water and real pharmaceutical wastewater are 90.5%, 72.2% and 85%, respectively. It is almost 13 times higher than that of pristine SnO2 nanorods in deionized water. The experimental evidence indicates that the highly conjugated linker between CuTPP–N3 and SnO2 plays a critical role for facilitating photoinduced electron transfer ability. This forms an efficient Z-scheme carrier transmission system in the hybrid. Therefore, the present work affords a well-designed molecule-engineered chromophore/oxide hybrid for highly efficient application in hydrogen evolution and environmental remediation.