Ru-Doped Ultrasmall Cu Nanoparticles Decorated with Carbon for Electroreduction of Nitrate to Ammonia

Electrocatalytic nitrate reduction reaction offers a sustainable approach to treating wastewater and synthesizing high-value ammonia under ambient conditions. However, electrocatalysts with low faradaic efficiency and selectivity severely hinder the development of nitrate-to-ammonia conversion. Herein, Ru-doped ultrasmall copper nanoparticles loaded on a carbon substrate (Cu–Ru@C) were fabricated by the pyrolysis of Cu-BTC metal–organic frameworks (MOFs). The Cu–Ru@C-0.5 catalyst exhibits a high faradaic efficiency (FE) of 90.4% at −0.6 V (vs RHE) and an ammonia yield rate of 1700.36 μg h–1mgcat.–1 at −0.9 V (vs RHE). Moreover, the nitrate conversion rate is almost 100% over varied pHs (including acid, neutral, and alkaline electrolytes) and different nitrate concentrations. The remarkable performance is attributed to the synergistic effect between Cu and Ru and the excellent conductivity of the carbon substrate. This work will open an exciting avenue to exploring MOF derivatives for ambient ammonia synthesis via selective electrocatalytic nitrate reduction.