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In this study, a novel visible-light-driven photocatalyst was designed based on unsymmetrical zinc− phthalocyanine photosensitizer on hierarchical porous TiO 2 (HPT) semiconductor. The HPT material has been prepared by a simple self-formation route. The present work successfully uses zinc phthalocyanine with spectral response extended to 700 nm triggers light harvesting center and HPT semiconductors for high photocatalytic H 2 production. This novel unsymmetrical zinc−phthalocyanine (PCH001) containing three tert-butyl and two carboxylic acid groups that act as "push" and "pull" electron transfer properties from the excited dye to the TiO 2 conduction band. The carboxylic group in the sensitizer serves as an anchoring group on to the surface of TiO 2 and to provide intimate electronic coupling between its excited-state wave function and the conduction-band manifold of the semiconductor. The excellent photophysical properties was governed further by choosing three tert-butyl groups which tuned the LUMO level of the sensitizer that provides directionality in the excited state in addition to low aggregation and high solubility. The Zn-PCH@TiO 2 composites exhibited promising activity and enhanced stability a photocatalytic system for visible-light-induced hydrogen production from water. The photocatalyst (HPT-0.25) shows H 2 production yield 2260 μmol and high turnover number (TON 18080) under visible/near IR light irradiation. Moreover, HPT-0.25 photocatalyst shows a broad visible/NIR light responsive range (400−800 nm) with high apparent quantum yields (AQY) of 7.15, 2.70, 11.57, 3.90, and 0.50% under λ = 420, 550, 690, 730, and 800 nm monochromatic light irradiation, respectively. The present work gives a new advance toward efficient solar energy conversion with promising visible/near IR light-driven photocatalytic activity.

Novel thiophenothiazine sensitized TiO2 photocatalysts show high photocatalytic hydrogen production from water splitting under visible light illumination.