Insights into the mechanism and aging of a noble-metal free H2-evolving dye-sensitized photocathode. Issue 32 (20th July 2018)

• Record Type: Journal Article
• Authors: Kaeffer, Nicolas; Windle, Christopher D.; Brisse, Romain; Gablin, Corinne; Leonard, Didier; Jousselme, Bruno; Chavarot-Kerlidou, Murielle; Artero, Vincent
• Is Part Of: Chemical science. Volume 9:Issue 32(2018)
• Page Start: 6721
• Page End: 6738
• Publication Date: 2018-07-20
• Subjects: Chemistry -- Periodicals; 540.5
• DOI: 10.1039/c8sc00899j
• Languages: English
• ISSNs: 2041-6520

Abstract

Abstract : Co-grafting of a cobalt diimine–dioxime catalyst and push–pull organic dye on NiO yields a photocathode evolving hydrogen from aqueous solution under sunlight, with equivalent performances compared to a dyad-based architecture using similar components. Abstract : Dye-sensitized photo-electrochemical cells (DS-PECs) form an emerging technology for the large-scale storage of solar energy in the form of (solar) fuels because of the low cost and ease of processing of their constitutive photoelectrode materials. Preparing such molecular photocathodes requires a well-controlled co-immobilization of molecular dyes and catalysts onto transparent semiconducting materials. Here we used a series of surface analysis techniques to describe the molecular assembly of a push–pull organic dye and a cobalt diimine–dioxime catalyst co-grafted on a p-type NiO electrode substrate. (Photo)electrochemical measurements allowed characterization of electron transfer processes within such an assembly and to demonstrate for the first time that a Co I species is formed as the entry into the light-driven H2 evolution mechanism of a dye-sensitized photocathode. This co-grafted noble-metal free H2 -evolving photocathode architecture displays similar performances to its covalent dye–catalyst counterpart based on the same catalytic moiety. Post-operando time-of-flight secondary ion mass spectrometry (ToF-SIMS) analysis of these photoelectrodes after extensive photoelectrochemical operation suggested decomposition pathways of the dye and triazole linkage used to graft the catalyst onto NiO, providing grounds for the design of optimized molecular DS-PEC components with increased robustness upon turnover.