Boosting the interlayer-confined nitrate reduction reaction by in situ electrochemical potassium ion intercalation

Electrochemically converting nitrate ions back to valuable ammonia (NH3) represents a sustainable alternative to the traditional Haber-Bosch process. However, NH3 electrosynthesis is currently restricted by the low catalytic activities and Faradaic efficiency (FE) of NO3−-to-NH3. Here we report an interlayer-confined nitrate reduction reaction (NTRR) in a two-dimensional layered structure. The results indicate that in situ electrochemical K+ intercalation expands the interlayer spacing, which triggers the NTRR between layers. The obtained α-Ni0.902Cu0.098(OH)2 ultrathin nanosheets deliver high NTRR performance with an NH3 yield rate of 13.4 mol gcat.−1 h−1 and O3−-to-NH3 FE of 98.9% at −0.6 V, far exceeding those of Cu-based electrocatalysts. Moreover, the catalyst exhibits good cycling stability, which can sustain 20 successive cycles without obvious decay of activity and NH3 FE. Meanwhile, in situ electrochemical Raman spectroscopy results unravel the NO3−-to-NH3 pathway.