Approaching Durable Single-Layer Fuel Cells: Promotion of Electroactivity and Charge Separation via Nanoalloy Redox Exsolution.

Single-layer fuel cells (SLFCs) based on a mixed semiconductor and an ionic conductor demonstrate a simplified material preparation and fabrication procedure and possess a potentially high performance. However, the operational stability and principle of SLFCs have not yet been convinced of either commercialization and fundamental interests. We hereby report on the employment of a perovskite oxide based phase structurally redox stable semiconductor prior to determine a possible solution that improves the durability of the SLFC. The feasible working principles are established and the in-depth understanding of the short-circuit-free phenomenon in the SLFC with the mixed ionic and electronic conductor is provided. Additionally, a smart material design and cell structure processing are also proposed. An extended non-stop testing period of up to two days confirms the project feasibility and improved durability of the SLFC, achieved by replacing the unstable lithiated oxide phase with redox stable perovskite oxide, though the electrochemical performance is sacrificed. The precipitated metal/alloy nanoparticle on perovskite oxide not only improves the electrode reaction kinetics but also facilitates the charge separation and ionic conduction in SLFC, consequently enhances the fuel cell performance and electrical efficiency. The results confirmed the potential of stable operation for future practical deployment of SLFCs via the appropriate selection of material and cell structure design. It is greatly believed that the physical junction has played a crucial role in overcoming the internal short circuit issue of SLFCs.