Visible-Light-Driven Hydrogen Evolution of PtNP/[Ru(bpy)3]2+/Polyampholyte Hybrid Hydrogels

• Published in: ACS applied polymer materials 2023-08, Vol.5 (8), p.6493-6503
• Main Authors: Çeper, Tolga, Nabiyan, Afshin, Neumann, Christof, Turchanin, Andrey, Schacher, Felix H.
• Format: Article
• Language: English
• ISSN: 2637-6105; 2637-6105
• DOI: 10.1021/acsapm.3c01051

The integration of catalysts and photosensitizers into a soft matter matrix is an important step for technological deployment and potential repair strategies. Here we present a polyelectrolyte hydrogel platform as a flexible and reusable heterogeneous catalyst for hydrogen evolution reaction (HER), combining polydehydroalanine (PDha) hydrogels with Pt nanoparticles (PtNPs). We demonstrate that the PDha hydrogel can readily adsorb the precursor salt at pH 7, allowing for an in situ capping agent-free synthesis of PtNPs upon UV irradiation. When combined with [Ru­(bpy)3]2+ via electrostatic attachment and irradiated under visible light, PtNPs@PDha hybrid hydrogels with 6000 ppm of Pt could evolve 6 μmol H2 after 32 h, which leads to a TON of 60 based on the Pt weight fraction, by adding triethylamine as a sacrificial e– donor in 1:1 MeOH/H2O. If the amount of Pt is reduced to 60 ppm, the obtained TON increased to 350, although the evolved H2 amount was reduced to 0.35 μmol. The water uptake of the hydrogel significantly decreased after the attachment of PtNPs and Ru dye. After photocatalytic HER, the characteristic bands of [Ru­(bpy)3]2+ (MC at 352 nm and MLCT at 454 nm) in the absorption spectrum of [Ru]@PtNPs@PDha hybrid hydrogels were shifted, presumably due to the degradation of dyes leading to a broad absorption band stretching toward 600 nm with a shoulder visible at 507 nm. Those degraded dyes were investigated by UV–Vis spectroscopy and could be released at low pH values due to the polyampholytic nature of the surrounding PDha hydrogel. Besides the high activity toward HER, the flexible nature of the herein presented hybrid hydrogels renders these materials interesting and promising systems for heterogeneous light-driven catalysis.