In Situ Engineered NiCoRu‐CeO 2 Interfaces for Active and Stable Ammonia Conversion Toward High‐Performance Direct Ammonia Protonic Ceramic Fuel Cells

Direct ammonia proton‐conducting ceramic fuel cells (DA‐PCFCs) emerge as one promising clean energy technology that directly utilizes ammonia as a hydrogen‐rich, zero‐carbon fuel. However, limited catalytic activity and structural instability of conventional Ni‐based anode under ammonia atmospheres impose daunting challenges in the practical DA‐PCFCs application. Here, we develop the stable NiCoRu‐CeO 2 catalytic heterointerface using the facile strategy of infiltration coupled with in situ conversion of the Ce 0.9 Co 0.09 Ru 0.01 O 2 (CCR) precursor on Ni‐BaCe 0.7 Zr 0.1 Y 0.1 Yb 0.1 O 3‐ δ (Ni‐BCZYYb) anode. The in situ engineered NiCoRu‐CeO 2 heterointerface synergistically promotes efficient ammonia decomposition and proton conduction, achieving a near‐complete and stable conversion efficiency close to 100% at 600°C under 300 h operation. Mechanism studies reveal that CCR‐induced electronic modulation facilitates sufficient charge transfer and downshifts the Ni d‐band center, thereby optimizing adsorption energetics of reactants and key intermediates, and mitigating the over‐binding of NH 3 toward an efficient and stable ammonia conversion process. Using CCR@Ni‐BCZYYb anodes, the assembled DA‐PCFCs exhibit a high peak power density of 1.06 W cm −2 at 650°C, and negligible degradation over 300 h of operation. This work provides an effective interface engineering strategy for developing highly active and durable ammonia‐fueled PCFCs.