Non-noble-metal catalysts for electrocatalytic ammonia oxidation

Ammonia emerges as a high-energy density, carbon-free medium for the storage, transport, and utilization of green electricity. To unlock its full potential as a sustainable energy carrier, the development of efficient, scalable, and cost-effective electrocatalysts for the ammonia oxidation reaction (AOR) is critical. This review highlights the urgent demand for replacing noble-metal catalysts with earth-abundant, non-noble-metal alternatives to drive scalable AOR applications. We present a comprehensive analysis of AOR mechanisms, catalyst design principles and electrolyte effects, alongside analytical frameworks for reaction monitoring and product quantification. Beyond fundamentals, we also explore transformative applications of non-noble-metal AOR catalysts in three key domains: (1) ammonia electrolysis for on-demand hydrogen production, (2) direct ammonia fuel cells for decentralized power generation, and (3) electrocatalytic wastewater remediation. By bridging mechanistic insights with practical engineering, this review identifies unresolved challenges, such as sluggish kinetics, catalyst stability and system integration, and proposes a technical roadmap toward non-noble-metal driven ammonia energy systems.