Abstract
The effect of nitric acid treatment on the electrochemical performance of porous Pt electrodes deposited on YSZ (abbreviation from yttria stabilized zirconia) electrolyte was investigated. Two identical symmetrical Pt/YSZ/Pt cells with porous Pt electrodes were fabricated, after which the electrodes of the first cell were kept as sintered, while those of the second cell were impregnated with HNO3 solution. The electrochemical behavior of the prepared electrodes was studied using impedance spectroscopy and cyclic voltammetry. Significant reduction of the polarization resistance of the HNO3-treated electrodes was revealed. The observed enhancement of the electrochemical performance of porous Pt electrodes was assumed to be caused by adsorption of NOx-species on YSZ and Pt surfaces, which promotes oxygen molecules dissociation and transport to the triple phase boundary by the “relay-race” mechanism. The obtained results allow for considering the nitric acid treatment of a porous Pt electrode as an effective way of electrode activation.
Highlights
Solid oxide fuel cells (SOFCs) are high−efficient electrochemical devices that convert the chemical energy of fuel directly into electrical energy by an environmental-friendly way
The influence of nitric acid treatment of porous Pt electrodes deposited on YSZ electrolyte on the electrochemical performance was investigated
Raman spectroscopy study showed the appearance of new Raman peaks for the HNO3 treated YSZ sample, which can be caused by formation of different types of nitrates
Summary
Solid oxide fuel cells (SOFCs) are high−efficient electrochemical devices that convert the chemical energy of fuel directly into electrical energy by an environmental-friendly way. Enhancement of SOFC electrodes activity is important to address this problem as the electrode performance is largely responsible for effective operation of solid oxide cells. The impregnation of porous electrodes with solutions of cerium or praseodymium nitrates, which decompose to the related oxides upon heating, was found to be effective for enhancement of the electrode performance [7,8,9,10]. The nitric acid impregnated into the porous electrode acts as a source of nitrogen oxides on heating, that should enhance the oxygen exchange at the YSZ/Pt interface. The impregnation of porous Pt electrodes with nitric acid can be used as a simple and cost-effective way of the electrode activation. The origin of the activation effect of the HNO3 treatment of a porous Pt electrode deposited on YSZ electrolyte was discussed
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