High performing triple-conductive Pr2NiO4+ anode for proton-conducting steam solid oxide electrolysis cell

The development of proton-conducting solid oxide electrolysis cells for the intermediate-temperature range application is largely hindered by the limited choice of adequate anode materials. In this study, the popular solid oxide fuel cell cathode material Pr2NiO4+ (PNO) is investigated as the anode for the electrolysis cell, considering its proton-conducting ability. The introduction of protons into the PNO lattice is confirmed through insertion-induced conductivity variation measurements. Good chemical compatibility is verified between PNO and BaZr0.2Ce0.6Y0.2O3- (BZCY) proton-conducting electrolyte. Excellent catalytic activity towards water splitting is observed for the PNO-BZCY composite anode, 0.52 cm(2) for 550 degrees C, 0.057 cm(2) for 700 degrees C. The water-splitting process is disclosed by impedance spectroscopy measured under different conditions. Due to proton conduction in PNO, the PNO surface is activated for electrochemical reactions. The non-charge transfer processes account little to the electrode resistance. The performance of the PNO-BZCY anode is determined by two charge transfer processes whose kinetics are governed the electrolyzing potential. This charge transfer-limiting nature is relatively benign since the electrode resistance has been found to exponentially reduce with increasing overpotential. Cathode-supported Ni-BZCY//BZCY//PNO-BZCY thin film electrolyte single cells are fabricated and characterized. approximate to 95% current efficiency is confirmed. At 700 degrees C, a current density of 977 mA cm(-2) is achieved at a 1.3 V electrolyzing potential, e.g. 0.37 V overpotential, which is one of the best performances of proton-conducting steam electrolysis cells so far. The PNO-BZCY anode accounts only for 16% of the overall polarization resistance at 700 degrees C. These findings prove that the triple-conductive PNO is a promising anode material for proton-based steam electrolysis cells.