Visible-to-Near-Infrared Light-Driven Photocatalytic Hydrogen Production Using Dibenzo-BODIPY and Phenothiazine Conjugate as Organic Photosensitizer

Abstract

A novel visible-to-near-infrared (visible-to-NIR) light-driven photocatalyst was prepared by loading a dibenzo-BODIPY-phenothiazine conjugate dye 1 as a panchromatic photosensitizer on hierarchical porous TiO2 (HPT) semiconductor. The sensitizer 1, which absorbed visible light at 638 and 440 nm with molecular extinction coefficients (e) of 1.23 × 105 and 1.80 × 104 M–1 cm–1, respectively, in THF due to the dibenzo-BODIPY and phenothiazine-based D−π–A systems, respectively, showed panchromatic absorption up to 780 nm when deposited on the Pt/HPT photocatalyst to produce Pt/HPT500/1. The photocatalytic activities were investigated in the presence of ascorbic acid as a sacrificial agent in phosphate buffer solution under irradiation with λ > 400 nm using a 300 W Xe lamp at 100 mW cm–2 light intensity. After 10-h irradiation, the system achieved a remarkable catalytic activity for the production of H2 with a turnover number (TON) value of 11100. The sustained activity was suggestive after two sequences of 10-...