High-performance precious metal-free direct ammonia fuel cells endowed by Co-doped Ni4Cu1 anode catalysts

Anion exchange membrane-based direct ammonia fuel cells (AEM-DAFCs) have attracted increasing attention due to the advantages of ammonia. However, the high Pt loading in the anode substantially hampers the practical implementation of AEM-DAFCs. Herein, the Ni4Cu1Cox (x = 0, 0.5, 1.0, 1.5 and 2.0)-BP catalysts were prepared for the first time, achieving the best ammonia oxidation reaction (AOR) performance at x = 1.5. Density functional theory calculations reveal that such improvement is ascribed to the lowered adsorption energy and the Gibbs free energy of AOR intermediates as Co doping introduces electron aggregation around O atoms. The AEM-DAFC based on Ni4Cu1Co1.5-BP anode can deliver a peak power density (PPD) of 115.7 mW cm−2 and an open circuit voltage of 0.75 V at 80 °C. According to our knowledge, such PPD is the highest among precious metal-free electrodes-based AEM-DAFCs, showing that the Ni4Cu1Co1.5-BP is a promising candidate for anode catalyst in AEM-DAFCs. [Display omitted] •The Co-doped Ni4Cu1-BP catalysts were synthesized for the first time.•Co doping can reduce the onset potential of the AOR and increase the AOR current.•DFT results reveal that Co doping can reduce the ∆G of AOR intermediates.•AEM-DAFCs with Ni4Cu1Co1.5-BP anode demonstrated the highest PPD of 115.7 mW cm−2.