Semi‐Synthetic Chlorophyll‐Carotenoid Dyad for Dye‐Sensitized Photocatalytic Hydrogen Evolution
Yanxiang Liu, Yuanlin Li, Gang Chen, Xiaofeng Wang, Ritsuko Fujii, Yumiko Yamano, Osamu Kitao, Takashi Nakamura, Shin‐ichi Sasaki
Abstract
Abstract A chlorin‐carotenoid dyad Dyad‐COOH possessing a C3 2 ‐carboxylic acid group and a carotenoid moiety at the terminal end of C17‐substituent is synthesized from naturally occurring chlorophyll‐ a as a new sensitizer for photocatalytic hydrogen evolution (PHE). Under the same experimental conditions, a maximum turnover number (TON) of PHE based on Dyad‐COOH/Pt/TiO 2 is much higher than those of Pt/TiO 2 ‐based photocatalysts sensitized by the corresponding chlorin carboxylic acid (Chl‐COOH) without carotenoid side chain, sole carotenoic acid (Car‐COOH), or their 1:1 (mol/mol) mixture. By co‐adsorbing different types of carboxylic acid, the TON of Chl‐COOH is found to be increased probably due to the suppression of chlorin aggregates on the TiO 2 surface. The Dyad‐COOH/Pt/TiO 2 exhibits excellent photocatalytic performance with the hydrogen evolution of 9147 µmol g −1 h −1 with TON of 425 when 43 µmol g −1 of dye is loaded on the Pt/TiO 2 catalyst, while a better TON of 556 is achieved by preparing the photocatalyst with 10 µmol g −1 of Dyad‐COOH. This study provides new ideas for utilizing traditional photosynthetic dyes to a low‐cost and highly‐efficient photosensitizer for PHE.