An Unbalanced Battle in Excellence: Revealing Effect of Ni/Co Occupancy on Water Splitting and Oxygen Reduction Reactions in Triple-Conducting Oxides for Protonic Ceramic Electrochemical Cells.

Porous electrodes that conduct electrons, protons, and oxygen ions with dramatically expanded catalytic active sites can replace conventional electrodes with sluggish kinetics in protonic ceramic electrochemical cells. In this work, a strategy is utilized to promote triple conduction by facilitating proton conduction in praseodymium cobaltite perovskite through engineering non-equivalent B-site Ni/Co occupancy. Surface infrared spectroscopy is used to study the dehydration behavior, which proves the existence of protons in the perovskite lattice. The proton mobility and proton stability are investigated by hydrogen/deuterium (H/D) isotope exchange and temperature-programmed desorption. It is observed that the increased nickel replacement on the B-site has a positive impact on proton defect stability, catalytic activity, and electrochemical performance. This doping strategy is demonstrated to be a promising pathway to increase catalytic activity toward the oxygen reduction and water splitting reactions. The chosen PrNi0.7 Co0.3 O3- δ oxygen electrode demonstrates excellent full-cell performance with high electrolysis current density of -1.48 A cm-2 at 1.3 V and a peak fuel-cell power density of 0.95 W cm-2 at 600 °C and also enables lower-temperature operations down to 350 °C, and superior long-term durability.

Highly Performing Chromate-Based Ceramic Anodes (Y0.7Ca0.3Cr1- xCu xO3-δ) for Low-Temperature Solid Oxide Fuel Cells.

Exploitation of alternative anode materials for low-temperature solid oxide fuel cells (LT-SOFCs, 350-650 °C) is technologically important but remains a major challenge. Here we report a potential ceramic anode Y0.7Ca0.3Cr1- xCu xO3-δ ( x = 0, 0.05, 0.12, and 0.20) (YCC) exhibiting relatively high conductivity at low temperatures (≤650 °C) in both fuel and oxidant gas conditions. Additionally, the newly developed composition (YCC12) is structurally stable in reducing and oxidizing gas conditions, indicating its suitability for SOFC anodes. The I- V characteristics and performance of the ceramic anode infiltrated with Ni-(Ce0.9Gd0.1O2-δ)(GDC) were determined using GDC/(La0.6Sr0.4CoO3-δ)(LSC)-based cathode supported SOFCs. High peak power densities of ∼1.2 W/cm2 (2.2A/cm2), 1 W/cm2 (2.0A/cm2), and 0.6 W/cm2 (1.3 A/cm2) were obtained at 600, 550, and 500 °C, respectively, in H2/3% H2O as fuel and air as oxidant. SOFCs showed excellent stability with a low degradation rate of 0.015 V kh-1 under 0.2 A/cm2. YCC-based ceramic anodes are therefore critical for the advancement of LT-SOFC technology.