Surface Reconstruction on Uniform Cu Nanodisks Boosted Electrochemical Nitrate Reduction to Ammonia

Abstract

The Haber–Bosch (HB) process has provided most of commercial ammonia at the expense of high energy consumption and high CO2 emission. Nitrate electroreduction is showing great potential as an alternative route for the green and scale-up synthesis of ammonia at ambient conditions. However, the performance has lagged due to lack of efficient electrocatalysts. In this work, we present the facile synthesis of uniform Cu nanodisks with exposed (111) facets as highly active electrocatalyst for electrochemical ammonia synthesis, delivering a high ammonia yield of 2.16 mg mg–1 cat h–1 and a maximum Faradaic efficiency of 81.1% at −0.5 V versus a reversible hydrogen electrode (RHE). The remarkable activity is originated from the surface reconstructed triatomic Cu clusters due to the cathodic deoxygenation process. As a result, the reconstructed surface shows enhanced affinity to the adsorption of nitrate ions which undergo successive break of three N–O bonds, followed by subsequent formation of three N–H bonds to finally form NH3. The present study provides the feasible preparation of Cu based advanced catalysts and a unique insight into the mechanism of nitrate electroreduction.

In situ reconstruction enhanced dual-site catalysis towards nitrate electroreduction to ammonia

“…Such durability is very comparable to that of state-of-the-art catalysts towards e-NRA, which could maintain high catalytic activity in 12 h tests. 19,29,32…”

“…Among previously reported e-NRA catalysts, Cu-based materials are highly attractive due to their favourable electronic structures towards nitrate adsorption and effective suppression of the competitive hydrogen evolution reaction (HER). 17,[23][24][25][26][27][28][29][30][31][32] A variety of Cu-based electrocatalysts have been reported for e-NRA, including Cu/Cu 2 O, PdCu/Cu 2 O hybrids and Cu x Ni y alloys, in which the active Cu sites were promoted by either Cu 2 O and/or Pd, Ni species. Although these catalysts could achieve high faradaic efficiency (FE NH 3 ) of NH 3 over 90% under certain conditions, they usually require negative working potential (vs. RHE) or a large overpotential exceeding 0.84 V (see Table S1 †).…”

Pulsed Nitrate-to-Ammonia Electroreduction Facilitated by Tandem Catalysis of Nitrite Intermediates

“…The mechanism of the NO 3 RR on Cu-based catalysts has been studied previously, suggesting two reduction processes including NO 3 − to NO 2 − and NO 2 − to NH 4 + corresponding to the cathodic waves at ∼ −0.5 and −0.8 V (Figure S6). 37 Product analysis, including the F.E. and the geometric surface area normalized Y.R.…”

Research Progress on Cu-Based Catalysts for Electrochemical Nitrate Reduction Reaction to Ammonia

“…(i) Cross sections of charge density difference on perfect surface and reconstructed surface, respectively. Reprinted from ref . Copyright 2022 American Chemical Society.…”

“…As the electrolysis continued, the concentration of NH 4 + -N in product decreased (Figure 6c), which may be due to the increased pH of electrolyte caused by NO 3 RR and decreased protons consumed by competitive HER. Wu and his co-workers 94 designed Cu nanodisks by controlling the growth of Cu (111) facets using oxygen and hexadecylamine. During the NO 3 RR process, the partially oxidized surface of the copper nanodisks was deoxidized to reconstruct the Cu (111) surface.…”