A Bio‐Inspired Dendritic MoO <sub>x</sub> Electrocatalyst for Efficient Electrochemical Nitrate Reduction to Ammonia
Yuan‐Zi Xu, Daniel F. Abbott, Robin N. Dürr, Tran Ngoc Huan, Victor Mougel
Abstract
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.