Renewable Energy, Vol.155, 1051-1059, 2020
Organic blue-colored D-A-pi-A dye-sensitized TiO2 for efficient and stable photocatalytic hydrogen evolution under visible/near-infrared-light irradiation
Photocatalytic splitting of water by titanium dioxide (TiO2) is considered as the most promising approach for the production of hydrogen fuel. However, a low utilization of the solar light spectrum still limits its photoconversion efficiency. Herein, two indeno[1,2-b]thiophene-based organic sensitizers (S5 and S6) are used to sensitize TiO2 to significantly enhance photocatalytic hydrogen production by broadening the spectral response to near-infrared-light region. The results revealed that the average H-2 evolution rates of S5@Pt/TiO2 and S6@Pt/TiO2 were 21.5 mmol g(-1)h(-1) and 7.2 mmol g(-1)h(-1), which were 11.3 and 3.9 fold than that of the Pt/TiO2 (1.85 mmol g(-1) h(-1)), respectively. Compared with donor-IT-acceptor (D-pi-A) dye S6, donor-acceptor-pi-acceptor (D-A-pi-A) blue-colored dye S5 possesses evident dominant in sensitizing TiO2, in which the auxiliary acceptor 2, 3-diphenylquinoxaline (QT) of S5 can effectively disperse donor electron distribution to improve the photo-stability and weak the deprotonation effect to enhance light-harvesting. More importantly, a highly apparent quantum efficiency (AQY) of 2.8% for S5@Pt/TiO2 was obtained at lambda = 700 nm monochromatic light, which is, to the best of our knowledge, a recorded value among the pure organic dye-sensitized TiO2 systems. This study offers important insights into the rational design of D-A-pi-A organic dye to sensitize TiO2 for highly efficient and stable photocatalytic hydrogen evolution. (C) 2020 Elsevier Ltd. All rights reserved.