Issue 7, 2024

Enhancing the stability of photocatalytic systems for hydrogen evolution in water by using a tris-phenyl-phenanthroline sulfonate ruthenium photosensitizer

Abstract

The family of ruthenium tris-bipyridine complexes remains among the most widely used molecular photosensitizers (PSs) to drive catalytic reactions using the energy of light. However, the main drawback of such PSs is the poor stability of their oxidized and reduced forms subject to ligand dissociation, especially in water that causes relatively fast deactivation of the photocatalytic systems. We were able to improve the stability and efficiency of a Ru based photocatalytic system for hydrogen production in water by using the water-soluble Na4[Ru((SO3Ph)2phen)3] derivative (RuSPhphen, (SO3Ph)2phen = disodium (1,10-phenanthroline-4,7-diyl)bis(benzenesulfonate)) in place of regular [RuII(bpy)]3Cl2 (Rubpy, bpy = 2,2′-bipyridine) PS. RuSPhphen was tested with the [CoIII(CR14)Cl2]Cl (Co) catalyst and ascorbate (HA) as a sacrificial electron donor under visible-light irradiation. The RuSPhphen absorption coefficient being twice as high compared to Rubpy and the excited-state lifetime being much longer, while keeping almost similar potentials, more efficient intermolecular electron transfers have been observed allowing the concentration of Ru PSs to decrease by 5-fold, i.e. to 100 μM, compared to previous studies with the Rubpy/Co/HA/H2A photocatalytic system. A substantially enhanced H2-evolving photocatalytic activity was obtained with RuSPhphen directly correlated to its better stability over Rubpy. With 1.1 M H2A/HA, at catalyst concentrations of 10 an 5 μM, the H2 production is two times higher compared to that obtained with Rubpy. When the H2A/HA concentration is decreased to 0.1 M, the stability of both Ru PSs is further improved although RuSPhphen still systematically outperforms Rubpy whatever the catalyst concentration, with TONs reaching up to 4770 at 5 μM catalyst. A faster electron transfer of the RuSPhphen excited state to HA has been observed by time-resolved luminescence compared to that of Rubpy, that could be ascribed to its much longer lifetime. In addition, a much higher rate constant for back electron transfer from the RuSPhphen˙ reduced state to HA˙ was determined by nanosecond transient absorption spectroscopy that could contribute to the higher stability of RuSPhphen during photocatalysis. The greater stability of RuSPhphen over Rubpy could also be correlated to the geometry of the SPhphen ligand that makes it less prone to dissociation in water in its reduced state.

Graphical abstract: Enhancing the stability of photocatalytic systems for hydrogen evolution in water by using a tris-phenyl-phenanthroline sulfonate ruthenium photosensitizer

Supplementary files

Article information

Article type
Paper
Submitted
30 11 2023
Accepted
23 2 2024
First published
23 2 2024
This article is Open Access
Creative Commons BY-NC license

Sustainable Energy Fuels, 2024,8, 1457-1472

Enhancing the stability of photocatalytic systems for hydrogen evolution in water by using a tris-phenyl-phenanthroline sulfonate ruthenium photosensitizer

F. Camara, J. S. Aguirre-Araque, J. Fortage and M. Collomb, Sustainable Energy Fuels, 2024, 8, 1457 DOI: 10.1039/D3SE01556D

This article is licensed under a Creative Commons Attribution-NonCommercial 3.0 Unported Licence. You can use material from this article in other publications, without requesting further permission from the RSC, provided that the correct acknowledgement is given and it is not used for commercial purposes.

To request permission to reproduce material from this article in a commercial publication, please go to the Copyright Clearance Center request page.

If you are an author contributing to an RSC publication, you do not need to request permission provided correct acknowledgement is given.

If you are the author of this article, you do not need to request permission to reproduce figures and diagrams provided correct acknowledgement is given. If you want to reproduce the whole article in a third-party commercial publication (excluding your thesis/dissertation for which permission is not required) please go to the Copyright Clearance Center request page.

Read more about how to correctly acknowledge RSC content.

Social activity

Spotlight

Advertisements