Simultaneous removal of NO_x and propane by solid electrolyte cells with La_0.5Pr_1.5-xBa_xNiO₄ bifunctional electrodes

Solid electrolyte cell is a novel gas purification approach, which has unique superiority in simultaneous nitrogen oxides (NO_x) and volatile organic compounds (VOCs) removal. The development of effective electrode materials and the comprehensive understanding of reaction mechanisms are essential to advancing this technology. In this study, La_0.5Pr_1.5-xBa_xNiO₄ (x = 0, 0.05, 0.1, 0.2) Ruddlesden-Popper perovskites were successfully synthesized for simultaneous NO_x and propane removal. Ba doping led to crystal contraction, increased surface area, and promoted the formation of high-valence Ni ions and oxygen vacancies. Theoretical calculations confirm that Ba-doped samples have a lower oxygen vacancy formation energy and a smaller energy gap, thereby improving surface activity and bulk charge transfer. Without the need for ammonia addition, La_0.5Pr_1.4Ba_0.1NiO₄ achieves 38.2 % NO_x conversion, 96.2 % propane conversion, 86.9 % N₂ selectivity and 91.6 % CO₂ selectivity in the presence of oxygen. In-situ electrochemical impedance spectra reveal that gas adsorption, dissociation and diffusion are the rate-limiting steps, and they are promoted by Ba doping. Oxygen decreases NO_x conversion but aids propane oxidation. Propane reduces partial NO_x, and the reaction products favor surface reaction processes. This study provides valuable theoretical insights into the design of advanced electrode materials and innovative strategies for the efficient and synergistic removal of NO_x and VOCs.