A Bio‐Inspired Dendritic MoOx Electrocatalyst for Efficient Electrochemical Nitrate Reduction to Ammonia

Abstract Drawing inspiration from the nitrate reductase enzymes, which catalyze nitrate to nitrite in nature, here a bio‐inspired, reduced molybdenum oxide (MoO x ) shell is introduced that is grown on top of a dendritic nickel foam core (Ni NF ). The resulting MoO x /Ni NF material is prepared via a facile, two‐step electrodeposition strategy using commercially available, low‐cost precursors. This catalytic material displays a remarkable faradaic efficiency (FE) of 99% at −0.5 V versus RHE and a high ammonia (NH 3 ) yield rate of up to 4.29 mmol h −1 cm −2 at −1.0 V versus RHE in neutral media. Most importantly, MoO x /Ni NF exhibits exceptional stability for the nitrate reduction reaction (NO 3 RR), maintaining operation for over 3100 h at a high current density of −650 mA cm −2 , with a yield rate of 2.6 mmol h −1 cm −2 and a stable average NH 3 FE of ≈83%. Through combined XPS and in situ Raman spectroscopy it is shown that the pronounced affinity of MoO x /Ni NF for nitrate is associated with a substantial presence of oxygen vacancies within the material.