A convenient approach to high purity hydrogen production is photo-electrochemical water splitting driven by solar energy. In this context, copper(I) oxide is an interesting p-type semiconductor with relatively low cost and the appropriate valence and conduction band energies. The literature reports a convenient method for preparing Cu2O based on the electrodeposition [1,2] onto Cr and Au nanolayers previously deposited on conducting glasses (e.g. FTO). In the present work, we aim at substituting these supports with the less hazardous and inexpensive Cu. Furthermore, a support made of electrodeposited Cu has the advantage of being prepared from the same deposition bath used for the deposition of the semiconductor, thus strongly simplifying the synthesis of the whole photoelectrode architecture. The results obtained in photocurrents with this metallic under-layer further overcome the ones obtained by the gold one. A larger dependence of photocurrents with deposition parameters of the metallic under-layer is also noticed. For this reason large matrix of sample were tested studying the influence of: temperature, amount of material, rate of deposition (current density), presence/absence of electrolyte convection, distance and dimension of the electrode both for metallic under-layer and for the semiconductor itself. In spite of the good values of recorded photocurrents, this material, as happens for other semiconductors in the framework of photo-electrochemical water splitting, is very unstable under work condition due to photo-degradation. In order to evaluate the photocurrent efficiency, a novel method using cavity micro-electrodes (CM-E) [3] and scanning electrochemical microscopy (SECM) is here presented. This system also allows to a rapid screening of semiconductor powders by quickly evaluating their photoactivity under working conditions. It uses SECM in Tip Generation- Substrate Collection (TG-SC) mode to determine the flux of product of interest (H2 in this case) with respect to the side reaction ones. References [1] Paracchino, A.; Brauer, J. C.; Moser, J. E.; Thimsen, E.; Grätzel, M. J. Phys. Chem. C 2012, 116, 7341 [2] Paracchino, A.; Laporte, V.; Sivula, K.; Grätzel, M.; Thimsen, E. Nature Materials 2011, 10, 456 [3] Morandi, S.; Minguzzi, A. Electrochem. Comm. 2015, 59, 100

Influence of Metallic Under-layer in the Performance of Cu2O Photocathode & Novel Method for the Investigation of Photoactive Semiconductor Materials Using Cavity Micro Tips (C-ME) & SECM / A. Visibile, A. Minguzzi, A. Vertova, S. Rondinini. ((Intervento presentato al 1. convegno Enerchem tenutosi a Firenze nel 2016.

Influence of Metallic Under-layer in the Performance of Cu2O Photocathode & Novel Method for the Investigation of Photoactive Semiconductor Materials Using Cavity Micro Tips (C-ME) & SECM

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

Abstract

A convenient approach to high purity hydrogen production is photo-electrochemical water splitting driven by solar energy. In this context, copper(I) oxide is an interesting p-type semiconductor with relatively low cost and the appropriate valence and conduction band energies. The literature reports a convenient method for preparing Cu2O based on the electrodeposition [1,2] onto Cr and Au nanolayers previously deposited on conducting glasses (e.g. FTO). In the present work, we aim at substituting these supports with the less hazardous and inexpensive Cu. Furthermore, a support made of electrodeposited Cu has the advantage of being prepared from the same deposition bath used for the deposition of the semiconductor, thus strongly simplifying the synthesis of the whole photoelectrode architecture. The results obtained in photocurrents with this metallic under-layer further overcome the ones obtained by the gold one. A larger dependence of photocurrents with deposition parameters of the metallic under-layer is also noticed. For this reason large matrix of sample were tested studying the influence of: temperature, amount of material, rate of deposition (current density), presence/absence of electrolyte convection, distance and dimension of the electrode both for metallic under-layer and for the semiconductor itself. In spite of the good values of recorded photocurrents, this material, as happens for other semiconductors in the framework of photo-electrochemical water splitting, is very unstable under work condition due to photo-degradation. In order to evaluate the photocurrent efficiency, a novel method using cavity micro-electrodes (CM-E) [3] and scanning electrochemical microscopy (SECM) is here presented. This system also allows to a rapid screening of semiconductor powders by quickly evaluating their photoactivity under working conditions. It uses SECM in Tip Generation- Substrate Collection (TG-SC) mode to determine the flux of product of interest (H2 in this case) with respect to the side reaction ones. References [1] Paracchino, A.; Brauer, J. C.; Moser, J. E.; Thimsen, E.; Grätzel, M. J. Phys. Chem. C 2012, 116, 7341 [2] Paracchino, A.; Laporte, V.; Sivula, K.; Grätzel, M.; Thimsen, E. Nature Materials 2011, 10, 456 [3] Morandi, S.; Minguzzi, A. Electrochem. Comm. 2015, 59, 100
PEC-WS; Cu2O; underlayer; semiconductor; SECM;
Settore CHIM/02 - Chimica Fisica
Influence of Metallic Under-layer in the Performance of Cu2O Photocathode & Novel Method for the Investigation of Photoactive Semiconductor Materials Using Cavity Micro Tips (C-ME) & SECM / A. Visibile, A. Minguzzi, A. Vertova, S. Rondinini. ((Intervento presentato al 1. convegno Enerchem tenutosi a Firenze nel 2016.
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/2434/480288
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