Levitation-guided disorder engineering unlocks efficient nitrite-to-ammonia electroconversion

초록

Electrocatalytic conversion of nitrite (NO2-) to ammonia (NH3) via the NO2- reduction reaction (eNO2RR) presents a promising approach. Prussian blue analog (PBA)-based electrocatalysts are potential candidates for eNO2RR 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 (Cu)-cobalt (Co) 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 sulfurization process is shown to be time-dependent in the formation of ordered/disordered flower-like CuCoPBA-S structures. CuCoPBA-S considerably influences the eNO2RR, achieving a NH3 faradaic efficiency (FE) of 80.91% and an NH3 yield rate of 3394.1 mu g 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 eNO2RR 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.Keywords: Prussian blue analog; Acoustic levitation; Nitrite reduction; Electrocatalysis; Ammonia synthesis.

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