Dibenzyl ether-guided microstructural regulation of PtIrZn catalysts for ammonia electrocatalysis

Abstract

Owing to their high theoretical energy density and carbon-free operation, fuel cells directly powered by ammonia have recently garnered substantial interest in the research community. However, the sluggish kinetics of the Ammonia Oxidation Reaction (AOR) significantly limit the practical applications of such ammonia-fueled systems. The ternary alloy catalyst PtIrZn has become a research focus due to its excellent electrocatalytic performance. However, designing PtIrZn nanocubes with high (100)-facet exposure to maximize AOR performance remains a major challenge. In this study, high (100)-facet-exposed PtIrZn nanocubes were successfully synthesized using a hydrothermal method, employing oleylamine as a reducing agent and dibenzyl ether as a morphology-directing agent. Transmission electron microscopy (TEM) and hydrogen adsorption–desorption characterization confirmed their cubic structure and high proportion of (100) facets. Electrochemical testing indicated that PtIrZn nanocubes exhibited a significant current density (163.94 A g_PtIr⁻¹) in the AOR, outperforming previously reported PtIrZn catalysts. Density Functional Theory (DFT) calculations further revealed that the (100) facets in the as-designed PtIrZn possess a lower reaction energy barrier and a more negative d-band center compared to the (111) facets. This leads to an enhanced dehydrogenation capacity of NH₃ and consequently accelerates the rate of the AOR.