Ampere-level current density ammonia electrochemical synthesis using CuCo nanosheets simulating nitrite reductase bifunctional nature

Abstract

The development of electrocatalysts capable of efficient reduction of nitrate (NO3−) to ammonia (NH3) is drawing increasing interest for the sake of low carbon emission and environmental protection. Herein, we present a CuCo bimetallic catalyst able to imitate the bifunctional nature of copper-type nitrite reductase, which could easily remove NO2− via the collaboration of two active centers. Indeed, Co acts as an electron/proton donating center, while Cu facilitates NOx− adsorption/association. The bio-inspired CuCo nanosheet electrocatalyst delivers a 100 ± 1% Faradaic efficiency at an ampere-level current density of 1035 mA cm−2 at −0.2 V vs. Reversible Hydrogen Electrode. The NH3 production rate reaches a high activity of 4.8 mmol cm−2 h−1 (960 mmol gcat−1 h−1). A mechanistic study, using electrochemical in situ Fourier transform infrared spectroscopy and shell-isolated nanoparticle enhanced Raman spectroscopy, reveals a strong synergy between Cu and Co, with Co sites promoting the hydrogenation of NO3− to NH3 via adsorbed *H species. The well-modulated coverage of adsorbed *H and *NO3 led simultaneously to high NH3 selectivity and yield.

Theory-Directed Designing of an Intrinsic-Activity-Modulated Metal-Doped Copper Oxide Electrode for Nitrate to Ammonia Synthesis

“…The X-ray diffraction (XRD) analysis of the Cu catalyst shows the alloying of the developed catalytic electrodes. Figure a displays a comparative XRD analysis of the pristine Cu, CuO, and the alloyed catalyst electrodes where the pristine Cu foam shows the characteristic Cu peaks at the 2-theta values of 43.56°, 50.73°, and 73.37° which correspond to the (111), (200), and (220) planes (JCPDF: 04-0836) . The high intensity of the Cu (111) plane shows the major phase of Cu.…”

“…The shifting of the diffraction peaks of the alloyed catalyst (Co−CuO) is credited to the interdigitated mixing of the two metals in the alloying process which changes the fringe width of the metals responsible for the alteration of catalytic activity. 44,46 Furthermore, the X-ray photoelectron However, in the case of pristine Cu, the observed O 1s B.E. peak corresponds to the surface oxides due to the atmospheric oxygen exposure.…”

“…Figure 3a displays a comparative XRD analysis of the pristine Cu, CuO, and the alloyed catalyst electrodes where the pristine Cu foam shows the characteristic Cu peaks at the 2-theta values of 43.56°, 50.73°, and 73.37°which correspond to the (111), (200), and (220) planes (JCPDF: 04-0836). 44 The high intensity of the Cu (111) plane shows the major phase of Cu. On the other hand, the presence of extra peaks at 36.82°and 61.75°arises from the CuO (JCPDF: 01-077-0199) that resulted after the chemical and thermal treatment of metallic Cu foam.…”

Electrochemical wastewater refining: a vision for circular chemical manufacturing

“…151 Tunable electrocatalysis for refining may require producing, stabilizing, and separating intermediates and controlling their delivery to distinct active sites. 152,153 For example, nitrite (formed by NO3RR at Ti) 64 could be isolated and directed in cascading reduction reactions toward inorganic products like ammonium, nitrous oxide, or nitric oxide at MoS2. 154,155 Electrocatalytic co-reduction of NO3 -and CO2 to form amines and amides is promising for heteroatom bond formation, which could be achieved in complex wastewater electrolytes.…”

Recent Advances in Electrocatalytic Nitrate Reduction to Ammonia: Mechanism Insight and Catalyst Design

“…Furthermore, the CuCo bimetallic catalyst, with two collaborative active centers, was presented to imitate the bifunctional nature of copper-type nitrite reductase. 124 The bioinspired CuCo catalyst delivers a 100 ± 1% FE and high activity of 960 mmol g cat −1 h −1 at an ampere-level current density of 1035 mA cm −2 , which could compete with the well-established Haber−Bosch process (200 mmol g cat −1 h −1 ). The results show that there is a strong interaction between Cu and Co, and the Co site promotes the hydrogenation of NO 3 − to NH 3 .…”