The use of sunlight to convert water into fuel is very attractive and ambitious since H2 is considered to be the energy carrier of the future thanks to its high mass energy density and its environmental friendliness [1,2]. Copper oxides-based photocathodes are attractive for their absorption in the visible range, low cost, high abundance and easy synthetic protocols as well as high photoactivity [3,4]. Two p-type semiconducting copper based materials has been prepared, characterized and tested as a photocathode for H2 production: CuO and Cu2O. The first one is prepared by thermal treatment of nanocrystalline CuI, which shows high efficiency in light conversion and interesting self-protection properties [5]. Cu2O instead was prepared by electrochemical deposition from a lactate-stabilized Cu++ bath [3]. Viceversa the main drawback of Cu(I) oxide is its lack of stability during photoelectrochemical conditions. For this material the influence of a metallic underlayer (Au, Cu) between the semiconductor itself and the FTO support was studied, together with the presence of a small load of Pt catalyst. In-situ and in-operando techniques like X-ray absorption near edge structure (XANES), Extended X-Ray Absorption Fine Structure (EXAFS) and Fixed Energy X-ray Absorption Voltammetry (FEXRAV) [6] allow us to better understanding materials behavior. We observe changes in copper oxidation states upon light and/ or applied potential. Moreover, the role of methanol as hole-scavenger during photoelectrochemical experiment has been studied. FEXRAV measurements allow following the material degradation processes and defining the stability windows. With differential light and dark XANES spectra, we investigated the local changes in electronic structure upon spectroelectrochemical conditions. These results will allow us obtaining more stable system for photoelectrochemical hydrogen production. References [1] G. Centi, S. Perathoner, ChemSusChem. 3 (2010) 195–208. [2] F. Malara, A. Minguzzi, M. Marelli, S. Morandi, R. Psaro, V. Dal Santo, A. Naldoni, ACS Catal. 5 (2015) 5292–5300. [3] A. Paracchino, V. Laporte, K. Sivula, M. Grätzel, E. Thimsen, Nat. Mater. 10 (2011) 456–461. [4] C. Li, T. Hisatomi, O. Watanabe, M. Nakabayashi, N. Shibata, K. Domen, J.-J. Delaunay, Energy Environ. Sci. 8 (2015) 1493–1500. [5] T. Baran, S. Wojtyła, C. Lenardi, P. Ghigna, E. Achilli, S. Rondinini, A. Minguzzi, ACS Appl. Mater. Interfaces. (submitted). [6] A. Minguzzi, O. Lugaresi, C. Locatelli, S. Rondinini, F. D’Acapito, E. Achilli. P. Ghigna. Anal. Chem. (2013), 85, 7009-7013.

Study of photoelectrochemical behavior of copper oxides based materials using X-ray absorption spectroscopy / A. Visibile, T. Baran, P. Ghigna, E. Achilli, M. Fracchia, A. Minguzzi, A. Vertova, S. Rondinini. ((Intervento presentato al convegno Giornate dell'Elettrochimica Italiana tenutosi a Gargnano nel 2016.

Study of photoelectrochemical behavior of copper oxides based materials using X-ray absorption spectroscopy

A. Visibile;T. Baran;A. Minguzzi;A. Vertova;S. Rondinini
2016

Abstract

The use of sunlight to convert water into fuel is very attractive and ambitious since H2 is considered to be the energy carrier of the future thanks to its high mass energy density and its environmental friendliness [1,2]. Copper oxides-based photocathodes are attractive for their absorption in the visible range, low cost, high abundance and easy synthetic protocols as well as high photoactivity [3,4]. Two p-type semiconducting copper based materials has been prepared, characterized and tested as a photocathode for H2 production: CuO and Cu2O. The first one is prepared by thermal treatment of nanocrystalline CuI, which shows high efficiency in light conversion and interesting self-protection properties [5]. Cu2O instead was prepared by electrochemical deposition from a lactate-stabilized Cu++ bath [3]. Viceversa the main drawback of Cu(I) oxide is its lack of stability during photoelectrochemical conditions. For this material the influence of a metallic underlayer (Au, Cu) between the semiconductor itself and the FTO support was studied, together with the presence of a small load of Pt catalyst. In-situ and in-operando techniques like X-ray absorption near edge structure (XANES), Extended X-Ray Absorption Fine Structure (EXAFS) and Fixed Energy X-ray Absorption Voltammetry (FEXRAV) [6] allow us to better understanding materials behavior. We observe changes in copper oxidation states upon light and/ or applied potential. Moreover, the role of methanol as hole-scavenger during photoelectrochemical experiment has been studied. FEXRAV measurements allow following the material degradation processes and defining the stability windows. With differential light and dark XANES spectra, we investigated the local changes in electronic structure upon spectroelectrochemical conditions. These results will allow us obtaining more stable system for photoelectrochemical hydrogen production. References [1] G. Centi, S. Perathoner, ChemSusChem. 3 (2010) 195–208. [2] F. Malara, A. Minguzzi, M. Marelli, S. Morandi, R. Psaro, V. Dal Santo, A. Naldoni, ACS Catal. 5 (2015) 5292–5300. [3] A. Paracchino, V. Laporte, K. Sivula, M. Grätzel, E. Thimsen, Nat. Mater. 10 (2011) 456–461. [4] C. Li, T. Hisatomi, O. Watanabe, M. Nakabayashi, N. Shibata, K. Domen, J.-J. Delaunay, Energy Environ. Sci. 8 (2015) 1493–1500. [5] T. Baran, S. Wojtyła, C. Lenardi, P. Ghigna, E. Achilli, S. Rondinini, A. Minguzzi, ACS Appl. Mater. Interfaces. (submitted). [6] A. Minguzzi, O. Lugaresi, C. Locatelli, S. Rondinini, F. D’Acapito, E. Achilli. P. Ghigna. Anal. Chem. (2013), 85, 7009-7013.
2016
PEC-WS; Copper oxide; XAS; hydrogen
Settore CHIM/02 - Chimica Fisica
Study of photoelectrochemical behavior of copper oxides based materials using X-ray absorption spectroscopy / A. Visibile, T. Baran, P. Ghigna, E. Achilli, M. Fracchia, A. Minguzzi, A. Vertova, S. Rondinini. ((Intervento presentato al convegno Giornate dell'Elettrochimica Italiana tenutosi a Gargnano nel 2016.
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/2434/480267
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