Ambient electrohydrogenation of N2 for NH3 synthesis on non-metal boron phosphide nanoparticles: the critical role of P in boosting the catalytic activity

Abstract

As a carbon-neutral alternative to the Haber–Bosch process, electrochemical N₂ reduction enables environment-friendly NH₃ synthesis under ambient conditions but needs active electrocatalysts for the N₂ reduction reaction (NRR). In this communication, we report on the first experimental demonstration that non-metal boron phosphide (BP) nanoparticles can be used as a high-efficiency catalyst for the ambient electrohydrogenation of N₂ to NH₃ with excellent selectivity. In 0.1 M HCl, this catalyst offers a high NH₃ yield of 26.42 μg h⁻¹ mg_cat.⁻¹ and a high faradaic efficiency of 12.7% at −0.60 V vs. the reversible hydrogen electrode, much superior to those of reported B catalysts. Such an enhancement is attributed to the fact that P in BP further weakens the NN bond while simultaneously strengthening the B–N bond and favors the exposure of more active sites for the NRR catalysis, which is supported by density functional theory calculations.