Efficient Electrochemical Nitrate Reduction to Ammonia with Copper‐Supported Rhodium Cluster and Single‐Atom Catalysts

Abstract

The electrochemical nitrate reduction reaction (NITRR) provides a promising solution for restoring the imbalance in the global nitrogen cycle while enabling a sustainable and decentralized route to source ammonia. Here, we demonstrate a novel electrocatalyst for NITRR consisting of Rh clusters and single‐atoms dispersed onto Cu nanowires (NWs), which delivers a partial current density of 162 mA cm−2 for NH3 production and a Faradaic efficiency (FE) of 93 % at −0.2 V vs. RHE. The highest ammonia yield rate reached a record value of 1.27 mmol h−1 cm−2. Detailed investigations by electron paramagnetic resonance, in situ infrared spectroscopy, differential electrochemical mass spectrometry and density functional theory modeling suggest that the high activity originates from the synergistic catalytic cooperation between Rh and Cu sites, whereby adsorbed hydrogen on Rh site transfers to vicinal *NO intermediate species adsorbed on Cu promoting the hydrogenation and ammonia formation.

Efficient Electroreduction of Nitrate into Ammonia at Ultralow Concentrations Via an Enrichment Effect

“…Notably, the j NH3 and FE NH3 values of Cu@C are comparable to those of the most advanced electrocatalysts for NO 3 − electroreduction at high concentrations (≥100 × 10 −3 m). [12,17,20,21,[25][26][27][28][29] The FE NH3 and yield rate of NH 3 for Cu@C with 100 × 10 −3 m NO 3 − decreased by only 3.8% and 13.4% after 20 rounds of successive reactions (Figure S16, Supporting Information).…”

“…[12,13] Cu-based catalysts are regarded as highly active for NO 3 − electroreduction, considering that metallic Cu with a large number of occupied d-orbital electrons can donate electrons to the lowest unoccupied π* orbital of NO 3 − . [14,15] Various Cu-based catalysts, including Cu-PCTDA, [16] Cu 50 Ni 50 , [17] Cu/Cu 2 O, [18] Ru-Cu nanowires, [19] CuFe bimetal, [20] and Rh@Cu, [21] have been reported recently for the electroreduction of NO 3 − into NH 3 with high selectivity and yield rate at high concentrations of NO 3 − (≥100 × 10 −3 m). To minimize the negative effects of NO 3 − , the World Health Organization has recommended a maximum concentration of 50 mg L −1 (0.81 × 10 −3 m) NO 3 − in drinking water.…”

Recent advances in nanostructured heterogeneous catalysts for N-cycle electrocatalysis

“…Indeed, the electrochemical nitrogen reduction reaction (NRR) is so difficult that it has inspired the development of nitrate reduction reaction (NO3RR) and nitric oxide reduction reactions (NORR) to produce NH3 [24]. The use of the more reactive but harmful NO3 − , NO2 − , NO, etc., as precursors can contribute to higher conversion efficiencies and is expected to reduce related environmental pollution [25][26][27][28][29][30][31][32][33][34][35]. Furthermore, as shown in Fig.…”

Lattice-strain and Lewis acid sites synergistically promoted nitrate electroreduction to ammonia over PdBP nanothorn arrays

“…31 The generated $H could promote the hydrogenation of reaction intermediates to produce ammonia. 43,44 Inspired by the above advances, we design and synthesize ternary PdBP nanothorn arrays (PdBP NAs) by a facile B,P-codoping strategy using Pd nanothorn arrays (Pd NAs) as structure and composition templates for efficient ammonia synthesis from nitrate. In such PdBP nanothorn arrays, the doped B and P atoms can serve as Lewis acid sites to enhance the adsorption of nitrate ions on the electrocatalyst surfaces.…”