In situ Cu_xO nanodecoration via rapid sputtering for tailoring surface nanostructure of oxygen electrodes

A rapid in-situ nanodecoration strategy is developed to enhance the durability of nanostructured La₀.₆Sr₀.₄CoO_3-δ (LSC) cathodes for solid oxide fuel cells. Cu nanoparticles (∼5 nm) are deposited onto nanoporous PLD-grown LSC surfaces via magnetron sputtering and subsequently oxidized to Cu_xO under 500 °C operating conditions. Initial electrochemical performance, including power density and polarization resistance, remains comparable between decorated and undecorated cells. However, the undecorated cathode exhibits rapid degradation, with resistance increasing from 1.6 to 3.25 Ω cm² over 23 h. In contrast, the Cu_xO-decorated cathode stabilizes after an initial conditioning period, maintaining a resistance of 1.75 Ω cm². The Cu nanoparticles retain their size during oxidation, indicating morphological stability. Constant-voltage operation reveals a >58% enhancement in current density over time for the decorated electrode. Impedance spectroscopy and distribution of relaxation times (DRT) analysis attribute the performance improvement to a marked reduction in charge transfer resistance. These results demonstrate a simple and scalable surface modification approach for improving the longevity and functionality of nanoporous oxide electrodes in electrochemical energy systems.