Electrochemical Ammonia Oxidation Catalysts for Direct Ammonia Fuel Cells

Ammonia has emerged as a prominent and key energy carrier due to its high energy density, carbon-free characteristics, and mature storage and transportation infrastructure. With regard to the utilization of ammonia energy, low-temperature direct ammonia fuel cells (DAFCs) offer a sustainable pathway for converting ammonia into electricity without generating greenhouse gases. However, the sluggish kinetics of the ammonia oxidation reaction (AOR) at the anode remain a major bottleneck to delivering high-performance DAFCs. Developing highly efficient electrocatalysts is therefore imperative to overcome this challenge. In this review, we first discuss the two widely accepted mechanisms of AOR. After that, we summarize the design strategies of Pt-based AOR electrocatalysts including crystal engineering, alloying engineering, and interface engineering from the perspective of balancing the adsorption behaviors of key intermediates. Meanwhile, representative AOR electrocatalysts are highlighted with particular focus on how these structural modification strategies regulate the catalytic performance via tuning the interaction with key intermediates. Finally, we present the current challenges and future perspectives in this field, aiming to provide insights toward the commercialization of DAFCs.