Synthesis of novel tetrazine based D-π-A organic dyes for photoelectrochemical and photocatalytic hydrogen evolution

• Published in: Journal of photochemistry and photobiology. A, Chemistry. Chemistry., 2020-03, Vol.390, p.112301, Article 112301
• Main Authors: Aslan, Emre, Karaman, Merve, Yanalak, Gizem, Bilgili, Hakan, Can, Mustafa, Ozel, Faruk, Patir, Imren Hatay
• Format: Article
• Language: English
• Subjects: Donor-π-acceptor dyes; Dye sensitization; Hydrogen evolution
• ISSN: 1010-6030; 1873-2666
• DOI: 10.1016/j.jphotochem.2019.112301

[Display omitted] •Tetrazine based two novel D-π-A organic dyes are synthesized for the first time.•First time MK-2 and MK-8 D-π-A dyes are used on photochemical hydrogen evolution.•Photoactivities are explored by electrochemical and chromatographic methods.•H2 rates are ascribed by structural, optical and electrochemical properties of dyes. Two novel donor-π-acceptor (D-π-A) dyes, called as MK-2 and MK-8, are synthesized. Their structural, optical and electrochemical properties are investigated by NMR, absorption/photoluminescence spectroscopies and cyclic voltammetry techniques, respectively. Photocatalytic and photoelectrochemical hydrogen evolution properties of these D-π-A dyes are explored by using triethanolamine (TEOA) as a sacrificial electron donor under anaerobic conditions and visible light irradiation with or without co-catalysts (Cu2WS4 and Pt) for the first time. Photoelectrochemical and photocatalytic hydrogen evolution reaction (HER) activities of these dyes are studied by using TiO2 coated FTO electrodes and powdered TiO2 (Degussa P25), respectively. Photoelectrochemical response of MK-2/TiO2 and MK-8/TiO2 are figured out in the order of 180 μA cm−1 and 80 μA cm−1. The photocatalytic hydrogen evolution amounts of MK-2/TiO2, MK-2/TiO2/Cu2WS4, MK-2/TiO2/Pt, MK-8/TiO2, MK-8/TiO2/Cu2WS4 and MK-8/TiO2/Pt are turned out to be 565, 920, 1828, 374, 522 and 1260 μmolg−1h−1, respectively. Dye/TiO2 photocatalysts are displayed good stability in the both photochemical HER experiments. The alteration in the HER activities of MK-2 and MK-8 is explained by molecule structures of dyes. The proposed mechanism of photocatalytic hydrogen evolution is clarified by using electrochemical band levels of each constituent.