In Situ Engineered NiCoRu-CeO2 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-CeO2 catalytic heterointerface using the facile strategy of infiltration coupled with in situ conversion of the Ce0.9Co0.09Ru0.01O2 (CCR) precursor on Ni-BaCe0.7Zr0.1Y0.1Yb0.1O3- δ (Ni-BCZYYb) anode. The in situ engineered NiCoRu-CeO2 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 NH3 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.