High Proton Conductivity in <i>x</i> CuO/(1‐ <i>x</i> )CeO <sub>2</sub> Electrolytes Induced by CuO Self‐Nucleation and Electron‐Ion Coupling
Muhammad Sharif, Sajid Rauf, Zuhra Tayyab, Muhammad Ahsan Masood, Yibin Tian, M.A.K. Yousaf Shah, Abdullah N. Alodhayb, Rizwan Raza, Bin Zhu
Abstract
Abstract Operating within the 300–500 °C range, low‐temperature solid oxide fuel cells (LT‐SOFCs) enable efficient and sustainable energy conversion, addressing the limitations of conventional high‐temperature SOFCs. However, achieving >0.1 S cm −1 ionic conductivity in electrolytes remains challenging. Here, a novel approach utilizing CuO self‐nucleation and electron‐ion (E‐I) coupling in x CuO/(1‐ x ) CeO 2 (CCO) semiconductor ionic membranes ( x = 0–0.4) is presented. At the optimal 0.2CuO/0.8CeO 2 composition, ionic conductivity exceeds 0.15 S cm −1 , driven by E‐I coupling at the CuO/CeO 2 heterojunction. This coupling creates a built‐in electric field (BIEF) via interfacial charge transfer, facilitating ion transport by lowering the activation energy for ion migration. The dual‐conduction pathway enabled by E‐I coupling not only facilitates electronic transfer and ionic transport but also optimizes charge transfer kinetics, achieving exceptional power densities of 750–900 mW cm −2 at 500–550 °C and 78 mW cm −2 at 300 °C. Density functional theory (DFT) calculations further validate the role of Cu 2+ and Ce 4+ valence states in generating interfacial charge transfer and enhancing ionic mobility. This innovative approach positions CuO/CeO 2 as a state‐of‐the‐art electrolyte, building the critical conductivity‐performance gap in LT‐SOFCs. This study pioneers LT‐SOFC innovation by leveraging E‐I coupling and electrode–electrolyte synergy, unlocking superior ion transport and practical applicability.