Levitation-Guided Disorder Engineering Unlocks Efficient Nitrite-to-Ammonia Electroconversion

Abstract

Electrocatalytic conversion of nitrite (NO2−) to ammonia (NH3) via the nitrate reduction reaction (eNO2RR) presents a promising approach. Prussian Blue analogs (PBAs)–based electrocatalysts are potential candidates for NO2RR owing to their good activity and selectivity. Herein, to the best of our knowledge, for the first time, we report a facile synthesis of a flower-like copper–cobalt PBA sulfide (CuCoPBA-S) using pulsed laser irradiation in liquid and investigate its formation mechanism using acoustic levitation coupled with in situ Raman spectroscopy. This approach enables contaminant-free, rapid, and cost-effective synthesis of electrocatalysts. The sulfidation process is shown to be time-dependent in the formation of ordered/disordered flower-like CuCoPBA-S structures. The CuCoPBA-S considerably influences the NO2RR, achieving a Faradaic efficiency (FE) of 80.91% and an NH3 yield rate of 3394.1 µg h−1 cm−2 at a fixed potential of −0.5 V vs. the reversible hydrogen electrode (RHE). Moreover, density functional theory analysis validates the NO2RR pathway facilitated by CuCoPBA-S during the electrocatalytic conversion of NO2− to NH3, and the rate-determining step in the pathway is the hydrogenation of *NH2O to *NH2OH.