Electrochemical Behavior of TiO x C y as Catalyst Support for Direct Ethanol Fuel Cells at Intermediate Temperature: From Planar Systems to Powders

• Published in: ACS applied materials & interfaces 2016-01, Vol.8 (1), p.716-725
• Main Authors: Calvillo, Laura, García, Gonzalo, Paduano, Andrea, Guillen-Villafuerte, Olmedo, Valero-Vidal, Carlos, Vittadini, Andrea, Bellini, Marco, Lavacchi, Alessandro, Agnoli, Stefano, Martucci, Alessandro, Kunze-Liebhäuser, Julia, Pastor, Elena, Granozzi, Gaetano
• Format: Article
• Language: English
• ISSN: 1944-8244; 1944-8252
• DOI: 10.1021/acsami.5b09861

To achieve complete oxidation of ethanol (EOR) to CO2, higher operating temperatures (often called intermediate-T, 150–200 °C) and appropriate catalysts are required. We examine here titanium oxycarbide (hereafter TiO x C y ) as a possible alternative to standard carbon-based supports to enhance the stability of the catalyst/support assembly at intermediate-T. To test this material as electrocatalyst support, a systematic study of its behavior under electrochemical conditions was carried out. To have a clear description of the chemical changes of TiO x C y induced by electrochemical polarization of the material, a special setup that allows the combination of X-ray photoelectron spectroscopy and electrochemical measurements was used. Subsequently, an electrochemical study was carried out on TiO x C y powders, both at room temperature and at 150 °C. The present study has revealed that TiO x C y is a sufficiently conductive material whose surface is passivated by a TiO2 film under working conditions, which prevents the full oxidation of the TiO x C y and can thus be considered a stable electrode material for EOR working conditions. This result has also been confirmed through density functional theory (DFT) calculations on a simplified model system. Furthermore, it has been experimentally observed that ethanol molecules adsorb on the TiO x C y surface, inhibiting its oxidation. This result has been confirmed by using in situ Fourier transform infrared spectroscopy (FTIRS). The adsorption of ethanol is expected to favor the EOR in the presence of suitable catalyst nanoparticles supported on TiO x C y .