IntechOpen
IntechOpen

Open access peer-reviewed article

A Perspective on Copper-Based Catalysts for Nitrate-to-Ammonia Electrochemical Reduction

Thi Kim Cuong Phu
Phi Long Nguyen
Thi Viet Bac Phung
Phuoc-Anh Le

This Article is part of Environmental Engineering/Green Technologies Section

Article metrics overview

115 Article Downloads

View Full Metrics

Article Type: Mini-review

Date of acceptance: July 2024

Date of publication: August 2024

DoI: 10.5772/geet.32

copyright: ©2024 The Author(s), Licensee IntechOpen, License: CC BY 4.0

Download for free

Table of contents

Nitrate-to-ammonia electrochemical reduction reaction
Copper-based catalysts for NO3RR
NO3RR performance by different Cu-based catalysts
Conclusions and future perspectives
Conflict of interest

Abstract

Nitrate widely exists in industrial wastewater and polluted groundwater as an environmental pollutant, resulting in severe environmental risks. The nitrate-to-ammonia electrochemical reduction reaction (NO3RR) is recognized as the most compelling solution for reducing environmental pollutants (NO) into the value-added product ammonia (NH3) due to compatibility with renewable energy. In recent years, copper-based electrocatalysts have emerged as one of the most promising methods for NO3RR owing to their relatively high catalytic activity and cost-effectiveness, also minimizing environmental impact. From this perspective, we summarize the function of copper-based catalysts in NO3RR. We also provide an overview of the current achievements of different copper-based catalysts for NO3RR. Furthermore, this perspective raises future challenges in designing highly effective and long-term stable catalysts for industrial-scale applications as well as in clarifying reaction pathways by theoretical and experimental characterization tools.

Keywords

  • nitrate-to-ammonia electrochemical reduction

  • highly effective Cu-based catalysts

Author information

Nitrate-to-ammonia electrochemical reduction reaction

Nitrogen is one of the most abundant and important elements on earth, and the global nitrogen cycle is a major biogeochemical cycle. However, wastes generated by anthropogenic activities, such as irrational wastes and the runoff of synthetic fertilizers, lead to excessive accumulation of the main N-containing pollutant, nitrate (NO), resulting in highly threatened ecological environments and human health [1–3]. Therefore, the need for the efficient removal of nitrate is an urgent concern [4, 5]. Currently, almost all traditional techniques for nitrate treatment suffer from incomplete NO removal and the formation of by-products, leading to high post-treatment costs and harsh operating conditions that significantly restrict their application [6, 7]. Compared with those approaches, the renewable energy-driven electrochemical reduction of nitrate-to-ammonia conversion has become a sustainable method to remove nitrate pollutants, and it simultaneously provides a promising alternative route to the conventional resource-intensive Haber–Bosch ammonia synthesis process (Figure 1) [8–12]. The nitrate-to-ammonia electrochemical reduction reaction (NO3RR) conducted under mild conditions is an ingenious approach, which utilizes nitrate and water as sources of nitrogen and hydrogen, respectively [13–15]. In contrast to the nitrogen reduction reaction (NRR), the NO3RR offers distinct advantages due to its ability to overcome the limited solubility of N2 in aqueous environment [16]. The NO3RR exhibits enhanced thermodynamic feasibility attributed to the lower dissociation energy of the N =O bond (204 kJ mol−1) compared to the N≡N bond (941 kJ mol−1), suggesting that the NO3RR is more thermodynamically favorable to occur than the NRR [17, 18]. Moreover, the standard reduction potential gap between the NO3RR and the hydrogen evolution reaction (HER) is much larger than that between the NRR and the HER, suggesting that the NO3RR can effectively avoid the interference of competitive HER [19].

Figure 1.

Concept cycle for green ammonia synthesis from waste nitrate.

The NO3RR involves a complex process of 9-proton and 8-electron transfer, yielding various by-products, including N2, NH2OH, N2H4, NO2, etc. [20, 21]. The NO3RR includes three important stages: (1) nitrate adsorption (NO3 → ∗NO3); (2) deoxygenation and hydrogenation of intermediates; (3) ammonia desorption (∗NH3 → NH3) [22–25]. Depending on the intrinsic catalysts, electrolytes, and working potential, one or more reaction pathways may exist simultaneously that affect the adsorption energy between key intermediates and the catalyst surface, as well as the energy barrier of each step, leading to unpredictable results [26–28].

Copper-based catalysts for NO3RR

Figure 2.

(a) Schematic illustration of boosting nitrate-to-ammonia electrochemical reduction through hydrogen gas evolution over Cu-based catalysts. (b) Cyclic voltammograms of a Cu-foam@mesh catalyst recorded in electrolytes with and without NO ions. Copper 3D-printed electrodes for ammonia electrosynthesis via nitrate reduction: (c) schematic representation of 3D printer deposition modeling technology, (d) SEM image of Cu treated with KCl, and (e) SEM image of Cu treated with NaHCO3. XPS spectra of (f) Cu 2p and (g) Co 2p of Co3O4 flocs and CuO NWAs@Co3O4 samples. (h) TEM image of CuxO/Ti3C2Tx composite. (i) NH3 yield for NH3 production of CuxO/Ti3C2Tx catalyst at various potentials. Figures 2a, 2b reproduced from Ref. [32], Copyright © (2023) American Chemical Society. Figures 2c, 2d, 2e reproduced from Ref. [33]. Copyright © (2023) American Chemical Society. Figures 2f, 2g reproduced from Ref. [46], Copyright © (2023) Elsevier. Figures 2h, 2i reproduced from Ref. [54], Copyright © (2023) Royal Society of Chemistry.

Copper and its derivatives are widely recognized as the most promising NO3RR electrocatalysts due to the unique electronic configuration accompanied by the strong Jahn–Teller effect, leading to high electrical conductivity, flexible atomic arrangement, and multiple oxidation states [29–31]. Endowed with a high specific surface area, spongy porous Cu foam material enhances effectively the mass transport pathway of nitrate reactants and facilitates the release of hydrogen bubbles, resulting in enhanced NO3-to-NH3 conversion performance (Figure 2a) [32]. Compared to the reduction process without NO, the current density increases significantly in the presence of NO, indicating the effectiveness of the porous Cu foam catalyst in NO3RR (Figure 2b). With the convenient synthesis method, the morphology of the copper 3D-printed electrode is modified by chemical treatment, leading to enhanced NO3RR performance. This advantage opens the avenue for developing industrial-scalable, easily fabricated on-site and efficient electrodes for nitrate reduction to ammonia (Figures 2c–e) [33]. However, the accumulation of nitrite (NO) ions on the copper surface results in rapid deactivation of Cu-based catalysts, which is the primary impediment hindering further hydrogenation to NH3 [34]. Besides that, Cu-based catalysts can be destabilized by the formation of the soluble [Cu(NH3)6]2+ complex in the presence of ammonia, hampering NH3 formation [35]. In order to alleviate these limitations, Cu-based catalysts have been modified by several strategies such as alloying [36–40], structural engineering [41, 42], surface engineering [43–45], and heterostructure engineering [46]. Among these approaches, heterostructure engineering is an effective method to optimize intrinsic catalytic activity by altering electronic properties [47]. Such interfacial interaction enables the integration of various active sites, catalyzing multi-step reactions, unlike one-component catalysts [48]. For example, a core–shell copper oxide–cobalt oxide heterostructure shows enhanced NO3RR performance due to the synergistic active phase and improved atomic hydrogen adsorption [46]. The electronic redistribution of Cu2+ and Co3+ in heterostructured CuO/Co3O4 can promote electron transfer and the hydrogenation step of N-intermediates, leading to enhanced NO3RR performance (Figures 2f, 2g).

MXenes are two-dimensional nanostructural transition metal–carbon/nitrite components, which are widely exploited for their large specific surface area and excellent electrical conductivity [49–51]. Previous studies have predicted and demonstrated that MXene-based catalysts enable the highly effective NO3-to-NH3 electroreduction under ambient conditions, especially with exposed metal atoms [52, 53]. For example, CuxO (111) anchored on MXene layers can overcome the individual disadvantages of Ti3C2Tx and CuxO, which are unfavorable for adsorbing the electron-rich nitrate and poor conductivity, respectively (Figure 2h) [54]. MXenes with nanoflake structure is favorable for CuxO anchoring and growing on its surface, leading to enhanced nitrate ion adsorption, sufficient charge transfer, and effective electron transport. Consequently, compared to either CuxO or Ti3C2Tx alone, the heterostructured component of Ti3C2Tx and CuxO shows excellent NO3RR performance (Figure 2i).

The water dissociation process concerned with the transformation of N-species has been proven to be a rate-determining step, which determines the NO3RR performance [55]. It has been shown that Cu nanoparticles can enhance the water dissociation ability by incorporating uncoordinated carboxylate ligands, leading to a boost in the hydrogenation of key intermediates, thereby reducing the overall energy barrier of NO3RR [56]. Besides that, organic molecules with lone electron pairs on N atoms are favorable to capture protons from OH− ions and form a positively charged surface, leading to the enrichment and fixation of NO ions on the catalyst surface [57]. The adsorbed H atom (H∗) can be electroreduced easily by the high positive charge density of protonated amine groups in the polyaniline (PANI) layer, which is a key hydrogenated species during NH3 performance [58].

NO3RR performance by different Cu-based catalysts

The NO3RR performance is strongly dependent on the pH of the electrolyte due to the effect of competitive HER [59]. The initial pH of the electrolyte plays a key role and cannot be neglected in the actual nitrate reduction process [60]. Each catalyst has a suitable pH range in which it yields the best performance. For instance, using density functional theory (DFT) calculations, Guo et al. found that both the catalytic deoxygenation and hydrogenation processes in NO3RR are substantially affected by the pH of copper [61]. Besides that, in a strongly acidic environment, Cu (100) is favorable for the conversion of NO to NH3, while Cu (111) is more effective in near-neutral and alkaline environments. Compared to an acidic electrolyte, an alkaline electrolyte is most suitable to obtain better NO3RR performance due to the competitive HER being unfavorable in the high-pH electrolyte [62]. However, due to excessive OH− ions competing with nitrate ions for adsorption sites, sluggish H+ kinetics to form NH3 reduces the NO3RR performance. For example, in Cu(I)–N3C1 sites, the NH3 yield rate plots a volcano trend and reaches the maximum (50.3 𝜇mol g h−1) at neutral and weak alkaline pH, indicating a favorable NO3RR [63].

Endowed with economical benefit and high effectiveness, the scalable Cu@Cu2+1O/NF nanorods with abundant oxygen vacancies and favorable charge/mass transfer are constructed with a facile approach. These merits lead to the rapid adsorption of nitrate and reduce the energy barrier of the rate-determining step, resulting in excellent performance with a NH3 Faradaic efficiency (FE) of 99.38% [64]. Notably, in a neutral electrolyte, Zang et al. proposed a single-atom Ni-alloyed Cu electrocatalyst with an FE of ∼100%, offering a competitive approach to synthesizing fertilizer with the Haber–Bosch process [65]. In an alkaline electrolyte, Gu et al. shed light on the heteroatom doping strategy for the synthesis of an excellent non-noble metal Cu-doped Fe3O4 with a NH3 FE of ∼100% [66]. Doping Fe3O4 with Cu can prevent the poisoning by ∗NO on the catalyst surface as well as lower the energy barrier of the reaction by strengthening intermediate adsorptions. Additionally, Hu et al. elucidate the relationship of the crystalline–amorphous phase in NO3RR. The amorphous Cu catalyst shows good NO3RR performance at low negative potential due to the enhanced protonation and suppression of the competitive HER. Based on data collected from the previous literature, the NO3RR performance comparison in neutral and alkaline electrolytes is summarized in Figures 3a, 3b and Tables 1 and 2.

Figure 3.

Performance comparison of different reported electrocatalysts for NO electroreduction to NH3 in (a) neutral electrolyte and (b) alkaline electrolyte. (Figure 3 is summarized from previous reports from Tables 1 and 2.) Red and pink stars display the NH3 Faradaic efficiency (%).

No. CatalystNH3 yield (𝜇g h−1 cm−2 or mg h−1 𝜇g)NH3 Faradaic efficiency (%)Applied potential (V) or current density (mA cm−2)Neutral electrolyteElectrolysis cell typeBy-productsReferences
1Ni/Cu2 O/Co(OH)x20,7402240 mA cm−2 12.5 mM Na2 SO4 + 30 mM NaNO3Undivided cellNO, N-gas, NH3[67]
2Cu/N2 O227,84070366 mA cm−2 0.5 M Na2 SO4 1000 ppm KNO3H-cellNO, H2, N2[68]
3Cu/Co3 O414,11090−1.05 V vs. RHE0.25 M Na2 SO4 + 2000 ppm NOH-cellNO[69]
4 Cu/Co/MOFs5098.396.4−0.6 V vs. RHE0.5 Na2 SO4 + 0.1 M NaNO3H-cellNO[70]
5 NiCu-SAA5553.9100−0.55 V vs. RHE0.5 M Na2 SO4 + 200 ppm NOH-cellNO[65]
6 PANI/CuO362193.88−1.3 V vs. SCE0.5 M K2 SO4 + 200 ppm NOH-cellNO, N2, NOx[71]
7 Au/Cu328199.69−0.8 V vs. RHE0.5 M Na2 SO4 + 100 ppm NOH-cellN2 , N2 O, H2 [39]
8 CoO/Cu430096.7−0.8 V vs. Ag/AgCl0.4 M Na2 SO4 + 0.04 M NOUndivided cellNO, H2[72]
9Cu/Cu2+1O20,14099.38−0.95 V vs. RHE (for yield value)0.1 M PBS + 0.05 M NOH-cellNO[64]
−0.55 V vs. RHE (for FE value)
10 Cu/N-doped C530287.2−1.1 V vs. RHE0.1 M PBS + 500 ppm NOUndivided cell-[73]
11 Cu/Pd/CuOx1510.384.04−1.3 V vs. SCE0.5 M K2 SO4 + 50 ppm NOH-cellNO[74]
12 Cu/MnOx29,30086.2−0.6 V vs. RHE0.1 M Na2 SO4 + 0.01 M KNO3H-cellN2 , H2 , NO[75]

Table 1

Performance comparison of Cu-based catalysts for NO electroreduction to NH3 in neutral electrolyte.

No. CatalystNH3 yield (𝜇g h−1 cm−2 or𝜇g h−1 mg)NH3 Faradaic efficiency (%)Applied potential (V) or current density (mA cm−2)Alkaline electrolyteElectrolysis cell typeBy-productsReferences
1Cu2O/Cu/Ti476092−0.5 V vs. RHE0.1 M KNO3 + 1 M KOHH-cellH2 , NO[76]
2 Cu–Rh21,59093−0.2 V vs. RHE0.1 M Na2 SO4 + 0.1 M KNO3H-cell-[77]
3Rux Cux/rGO646098−0.05 V vs. RHE0.1 M KNO3 + 1 M KOHH-cellNO, H2[37]
4 Cu NS390.199.7−0.15 V vs. RHE0.1 KOH + 0.01 KNO3 H-cell-[78]
5 CuPd/BCN102,15391.47−0.6 V vs. RHE0.1 KOH + 0.1 M NOH-cellNO, N2[79]
6 Cu@N-doped C234695.5−1.0 V vs. RHE1 M KOH + 1 M KNO3 H-cell (flow cell is also used)N2 , H2, NO[80]
7CuCo2 O4/CFs670681.9−0.3 V vs. RHE1 M KOH + 0.1 M NOH-cell N2, H2, NO[81]
8 Cu@MOF843996−0.2 V vs. RHE1 M KOH + 0.1 M NOH-cellN2 H4, H2, N2, NO [56]
9Cu-doped Fe3 O4179,550100−0.6 V vs. RHE0.1 M KOH + 0.1 M KNO3 H-cell-[66]
10 Cu–Pd/C220.862.3−0.4 V vs. RHE0.1 M KOH + 10 mM NOFlow cellNO[82]
11Ir&Cu/Cu2O4800900 V vs. RHE1 M KOH + 0.1 M KNO3 H-cellN2 H4, NO[83]
12 Amorphous Cu24,14095.7−0.3 V vs. RHE0.5 M Na2 SO4 + 0.05 M NaNO3 H-cellH2 , N2 H4 , NO [84]

Table 2

Performance comparison of Cu-based catalysts for NO electroreduction to NH3 in alkaline electrolyte.

Conclusions and future perspectives

In this work, we provide a review of the progress in research regarding the nitrate-to-ammonia electrochemical reduction of Cu-based catalysts. With the rapid development of renewable electricity technology in the global energy sector, the past decade has witnessed unprecedented opportunities to sustainably convert naturally and artificially polluted NO resources into fuels and the value-added chemical compound NH3. Electrochemical reduction, with its high efficiency and good environmental compatibility characteristics, holds great promise as a method for treating nitrate pollution in water. As electrochemical reduction of nitrate relies heavily on catalysts, Cu-based catalysts are currently one of the most promising candidates for NO3RR due to their special properties and cost-effectiveness. Nevertheless, their unstable properties and unclear reaction pathways make it difficult to apply them in industrial-scale applications as well as to develop or optimize synthesis strategies to enhance NO3RR performance. Besides that, real-life applications of NO3RR should consider different NO sources with different NO concentrations such as in industrial wastewater or groundwater. Therefore, the commercialization of highly efficient Cu-based electrocatalysts for NO3RR that can work well in different experimental conditions is interesting but still challenging.

Substantial research has been devoted to NO3RR utilizing copper catalysts, but the reaction mechanisms remain elusive. The DFT is employed to gain insight into the NO3RR mechanism to help understand the reaction step at the molecular level from the view of thermodynamics. Even though the DFT is not sufficient to provide accurate explanations about reaction pathways, combining it with cutting-edge equipment can sufficiently explain NO3RR pathways. Conventional ex situ characterization tools are insufficient for identifying changes in the structure and composition of catalysts that occur during the electroreduction process driven by an external electric field. For instance, operando Raman spectroscopy, in situ Fourier-transform infrared spectroscopy, in situ differential electrochemical mass spectrometry, and in situ electron spin resonance measurements can elucidate the NO3RR pathways through offering real-time signals for the intermediates/products during the electroreduction process. Therefore, using state-of-the-art in situ differential characterization to monitor in real time the reaction at the electrode–electrolyte interface is a powerful approach to revealing feasible reaction pathways and dynamic structures of N-intermediates.

Conflict of interest

The authors declare no conflict of interest.

References

  1. 1.
    Du H, Guo H, Wang K, Du X, Beshiwork BA, Sun S, Durable electrocatalytic reduction of nitrate to ammonia over defective pseudobrookite Fe2TiO5 nanofibers with abundant oxygen vacancies. Angew Chem Int Ed. 2023;62(5):e202215782. doi:10.1002/anie.202215782.
  2. 2.
    Liu D, Qiao L, Chen Y, Zhou P, Feng J, Leong CC, Electrocatalytic reduction of nitrate to ammonia on low-cost manganese-incorporated Co3O4 nanotubes. Appl Catal B. 2023;324: 122293. doi:10.1016/j.apcatb.2022.122293.
  3. 3.
    Xu S, Shi Y, Wen Z, Liu X, Zhu Y, Liu G, Polystyrene spheres-templated mesoporous carbonous frameworks implanted with cobalt nanoparticles for highly efficient electrochemical nitrate reduction to ammonia. Appl Catal B. 2023;323: 122192. doi:10.1016/j.apcatb.2022.122192.
  4. 4.
    Xi Z, Wang J, Liu B, Xu X, Jing P, Gao R, Elaborately tuning the electronic structure of single-atom nickel sites using nickel nanoparticles to markedly enhance the electrochemical reduction of nitrate into ammonia. J Energy Chem. 2023;83: 32–42. doi:10.1016/j.jechem.2023.03.037.
  5. 5.
    Paul S, Sarkar S, Adalder A, Kapse S, Thapa R, Ghorai UK. Strengthening the metal center of Co-N4 active sites in a 1D-2D heterostructure for nitrate and nitrogen reduction reaction to ammonia. ACS Sustain Chem Eng. 2023;11(16):6191–6200. doi:10.1021/acssuschemeng.2C07114.
  6. 6.
    Rashid R, Shafiq I, Akhter P, Iqbal MJ, Hussain M. A state-of-the-art review on wastewater treatment techniques: the effectiveness of adsorption method. Environ Sci Pollut Res. 2021;28(8):9050–9066. doi:10.1007/S11356-021-12395-x.
  7. 7.
    Abascal E, Gómez-Coma L, Ortiz I, Ortiz A. Global diagnosis of nitrate pollution in groundwater and review of removal technologies. Sci Total Environ. 2022;810: 152233. doi:10.1016/j.dcitotenv.2021.152233.
  8. 8.
    Humphreys J, Lan R, Tao S. Development and recent progress on ammonia synthesis catalysts for Haber–Bosch process. Adv Energy Sustainability Res. 2021;2(1):2000043. doi:10.1002/aesr.202000043.
  9. 9.
    Zhu D, Li G, Yan X, Geng C, Gao L. Electrochemical nitrate reduction to high-value ammonia on two-dimensional molybdenum carbide nanosheets for nitrate-containing wastewater upcycling. Sci Total Environ. 2023;878: 163145. doi:10.1016/j.dcitotenv.2023.163145.
  10. 10.
    Sun L, Yao H, Wang Y, Zheng C, Liu B. Mesostructures engineering to promote selective nitrate-to-ammonia electroreduction. Adv Energy Mater. 2023;2303054. doi:10.1002/aenm.202303054.
  11. 11.
    Jia Y, Ji YG, Xue Q, Li FM, Zhao GT, Jin PJ, Efficient nitrate-to-ammonia electroreduction at cobalt phosphide nanoshuttles. ACS Appl Mater Interfaces. 2021;13(38):45521–45527. doi:10.1021/acsami.1c12512.
  12. 12.
    Zhang G, Wang F, Chen K, Kang J, Chu K. Atomically dispersed Sn confined in FeS2 for nitrate-to-ammonia electroreduction. Adv Funct Mater. 2023;2305372. doi:10.1002/adfm.202305372.
  13. 13.
    Du F, Li J, Wang C, Yao J, Tan Z, Yao Z, Active sites-rich layered double hydroxide for nitrate-to-ammonia production with high selectivity and stability. Chem Eng J. 2022;434: 134641. doi:10.1016/j.cej.2022.134641.
  14. 14.
    Li R, Gao T, Wang P, Qiu W, Liu K, Liu Y, The origin of selective nitrate-to-ammonia electroreduction on metal-free nitrogen-doped carbon aerogel catalysts. Appl Catal B. 2023;331: 122677. doi:10.1016/j.apcatb.2023.122677.
  15. 15.
    Yu Y, Wang C, Yu Y, Wang Y, Zhang B. Promoting selective electroreduction of nitrates to ammonia over electron-deficient Co modulated by rectifying Schottky contacts. Sci China Chem. 2020;63(10):1469–1476. doi:10.1007/s11426-020-9795-x.
  16. 16.
    Liu S, Wang S, Wang P, Huang Z, Wang T, Lei A. 1,2-amino oxygenation of alkenes with hydrogen evolution reaction. Nat Commun. 2022;13(1):4430. doi:10.1038/s41467-022-32084-8.
  17. 17.
    Zhang N, Wang G, Zhang G, Chen K, Chu K. Electrochemical nitrate-to-ammonia reduction over atomic Fe-dopants incorporated in CoS2. Chem Eng J. 2023;474: 145861. doi:10.1016/j.cej.2023.145861.
  18. 18.
    Li H, Wang Y, Chen S, Peng F, Gao F. Boosting electrochemical reduction of nitrate to ammonia by constructing nitrate-favored active Cu–B sites on SnS2. Small. 2024;2308182. doi:10.1002/smll.202308182.
  19. 19.
    Chen W, Yang X, Chen Z, Ou Z, Hu J, Xu Y, Emerging applications, developments, prospects, and challenges of electrochemical nitrate-to-ammonia conversion. Adv Funct Mater. 2023;33(29):2300512. doi:10.1002/adfm.202300512.
  20. 20.
    Harmon NJ, Li J, Wang BT, Gao Y, Wang H. Influence of carbon nanotube support on electrochemical nitrate reduction catalyzed by cobalt phthalocyanine molecules. ACS Catal. 2024;14: 3575–3581. doi:10.1021/acscatal.3c05540.
  21. 21.
    Hai Y, Li X, Cao Y, Wang X, Meng L, Yang Y, Ammonia synthesis via electrocatalytic nitrate reduction using NiCoO2 nanoarrays on a copper foam. ACS Appl Mater Interfaces. 2023;16: 11431–11439. doi:10.1021/acsami.3c16456.
  22. 22.
    Xue ZH, Shen HC, Chen P, Pan GX, Zhang WW, Zhang WM, Boronization of nickel foam for sustainable electrochemical reduction of nitrate to ammonia. ACS Energy Lett. 2023;8(9):3843–3851. doi:10.1021/acsenergylett.3c01139.
  23. 23.
    Wang W, Chen J, Tse ECM. Synergy between Cu and Co in a layered double hydroxide enables close to 100% nitrate-to-ammonia selectivity. J Am Chem Soc. 2023;145(49):26678–26687. doi:10.1021/jacs.3c08084.
  24. 24.
    Zhang G, Wang G, Wan Y, Liu X, Chu K. Ampere-level nitrate electroreduction to ammonia over monodispersed Bi-doped FeS2. ACS Nano. 2023;17(21):21328–21336. doi:10.1021/acsnano.3c05946.
  25. 25.
    Huang Z, Yang B, Zhou Y, Luo W, Chen G, Liu M, Tungsten nitride/tungsten oxide nanosheets for enhanced oxynitride intermediate adsorption and hydrogenation in nitrate electroreduction to ammonia. ACS Nano. 2023;17(24):25091–25100. doi:10.1021/acsnano.3c07734.
  26. 26.
    Wang K, Mao R, Liu R, Zhang J, Zhao H, Ran W, Intentional corrosion-induced reconstruction of defective NiFe layered double hydroxide boosts electrocatalytic nitrate reduction to ammonia. Nat Water. 2023;1(12):1068–1078. doi:10.1038/s44221-023-00169-3.
  27. 27.
    Dai J, Tong Y, Zhao L, Hu Z, Chen CT, Kuo CY, Spin polarized Fe1–Ti pairs for highly efficient electroreduction nitrate to ammonia. Nat Commun. 2024;15(1):1–11. doi:10.1038/s41467-023-44469-4.
  28. 28.
    Sun S, Dai C, Zhao P, Xi S, Ren Y, Tan HR, Spin-related Cu–Co pair to increase electrochemical ammonia generation on high-entropy oxides. Nat Commun. 2024;15(1):1–13. doi:10.1038/s41467-023-44587-z.
  29. 29.
    Wang C, Ye F, Shen J, Xue KH, Zhu Y, Li C. In situ loading of Cu2O active sites on island-like copper for efficient electrochemical reduction of nitrate to ammonia. ACS Appl Mater Interfaces. 2022;14(5):6680–6688. doi:10.1021/acsami.1c21691.
  30. 30.
    Yang R, Li H, Long J, Jing H, Fu X, Xiao J. Potential dependence of ammonia selectivity of electrochemical nitrate reduction on copper oxide. ACS Sustain Chem Eng. 2022;10(43):14343–14350. doi:10.1021/acssuschemeng.2c04847.
  31. 31.
    Tyagi NK, Mahapatra BK, Ghimire S, Manna N, Kumar D, Kumar V, Theory-directed designing of an intrinsic-activity-modulated metal-doped copper oxide electrode for nitrate to ammonia synthesis. ACS Appl Energy Mater. 2023;6(11):6111–6119. doi:10.1021/acsaem.3c00617.
  32. 32.
    Wang Y, Dutta A, Iarchuk A, Sun C, Vesztergom S, Broekmann P. Boosting nitrate to ammonia electroconversion through hydrogen gas evolution over Cu-Foam@mesh catalysts. ACS Catal. 2023;13(12):8169–8182. doi:10.1021/acscatal.3c00716.
  33. 33.
    Perales-Rondon JV, Rojas D, Gao W, Pumera M. Copper 3D-printed electrodes for ammonia electrosynthesis via nitrate reduction. ACS Sustain Chem Eng. 2023;11(18):6923–6931. doi:10.1021/acssuschemeng.2c06851.
  34. 34.
    Fang JY, Zheng QZ, Lou YY, Zhao KM, Hu SN, Li G, Ampere-level current density ammonia electrochemical synthesis using CuCo nanosheets simulating nitrite reductase bifunctional nature. Nat Commun. 2022;13(1):1–13. doi:10.1038/s41467-022-35533-6.
  35. 35.
    Reyter D, Bélanger D, Roué L. Optimization of the cathode material for nitrate removal by a paired electrolysis process. J Hazard Mater. 2011;192(2):507–513. doi:10.1016/j.jhazmat.2011.05.054.
  36. 36.
    Wu A, Zhou Y, Lv J, Zhang D, Peng Y, Ye Q, Boosting electrocatalytic nitrate-to-ammonia conversion via plasma enhanced CuCo alloy-substrate interaction. ACS Sustain Chem Eng. 2022;10(44):14539–14548. doi:10.1021/acssuschemeng.2c04249.
  37. 37.
    Gao W, Xie K, Xie J, Wang X, Zhang H, Chen S, Alloying of Cu with Ru enabling the relay catalysis for reduction of nitrate to ammonia. Adv Mater. 2023;35(19):2202952. doi:10.1002/adma.202202952.
  38. 38.
    Paliwal A, Bandas CD, Thornburg ES, Haasch RT, Gewirth AA. Enhanced nitrate reduction activity from Cu-alloy electrodes in an alkaline electrolyte. ACS Catal. 2023;13(10):6754–6762. doi:10.1021/acscatal.3c00999.
  39. 39.
    Yin H, Peng Y, Li J. Electrocatalytic reduction of nitrate to ammonia via a Au/Cu single atom alloy catalyst. Environ Sci Technol. 2023;57(8):3134–3144. doi:10.1021/acs.est.2c07968.
  40. 40.
    Wang Y, Xu A, Wang Z, Huang L, Li J, Li F, Enhanced nitrate-to-ammonia activity on copper-nickel alloys via tuning of intermediate adsorption. J Am Chem Soc. 2020;142(12):5702–5708. doi:10.1021/jacs.9b13347.
  41. 41.
    Liu F, Chen C, Jiang X, Guo JY, Wei Y, Li JW, High-index surface structure engineering of Au-Pd concave triple-octahedrons for boosting electrocatalytic nitrate reduction to ammonia. ACS Sustain Chem Eng. 2023;11(5):1631–1637. doi:10.1021/acssuschemeng.2c07101.
  42. 42.
    Zhao Y, Liu Y, Zhang Z, Mo Z, Wang C, Gao S. Flower-like open-structured polycrystalline copper with synergistic multi-crystal plane for efficient electrocatalytic reduction of nitrate to ammonia. Nano Energy. 2022;97: 107124. doi:10.1016/j.nanoen.2022.107124.
  43. 43.
    Zhong W, Gong Z, He Z, Zhang N, Kang X, Mao X, Modulating surface oxygen species via facet engineering for efficient conversion of nitrate to ammonia. J Energy Chem. 2023;78: 211–221. doi:10.1016/j.jechem.2022.11.024.
  44. 44.
    Gong Z, Zhong W, He Z, Liu Q, Chen H, Zhou D, Regulating surface oxygen species on copper (I) oxides via plasma treatment for effective reduction of nitrate to ammonia. Appl Catal B. 2022;305: 121021. doi:10.1016/j.apcatb.2021.121021.
  45. 45.
    Ren T, Ren K, Wang M, Liu M, Wang Z, Wang H, Concave-convex surface oxide layers over copper nanowires boost electrochemical nitrate-to-ammonia conversion. Chem Eng J. 2021;426: 130759. doi:10.1016/J.CEJ.2021.130759.
  46. 46.
    Liu H, Li J, Du F, Yang L, Huang S, Gao J, A core–shell copper oxides-cobalt oxides heterostructure nanowire arrays for nitrate reduction to ammonia with high yield rate. Green Energy Environ. 2023;8(6):1619–1629. doi:10.1016/j.gee.2022.03.003.
  47. 47.
    Wang H, Guo Y, Li C, Yu H, Deng K, Wang Z, Cu/CuOxIn-plane heterostructured nanosheet arrays with rich oxygen vacancies enhance nitrate electroreduction to ammonia. ACS Appl Mater Interfaces. 2022;14(30):34761–34769. doi:10.1021/acsami.2c08534.
  48. 48.
    Yang L, Li J, Du F, Gao J, Liu H, Huang S, Interface engineering cerium-doped copper nanocrystal for efficient electrochemical nitrate-to-ammonia production. Electrochim Acta. 2022;411: 140095. doi:10.1016/j.electacta.2022.140095.
  49. 49.
    Wang Q, Yuan H, Zhang M, Yang N, Cong S, Zhao H, A highly conductive and supercapacitive MXene/N-CNT electrode material derived from a MXene-Co-Melamine precursor. ACS Appl Electron Mater. 2023;5(5):2506–2517. doi:10.1021/acsaelm.2c01768.
  50. 50.
    Wang Y, Li L, Shen M, Tang R, Zhou J, Han L, Simple one-step molten salt method for synthesizing highly efficient MXene-supported Pt nanoalloy electrocatalysts. Adv Sci. 2023;10(33):2303693. doi:10.1002/advs.202303693.
  51. 51.
    Zhou S, Zhao Y, Shi R, Wang Y, Ashok A, Héraly F, Vacancy-rich MXene-immobilized Ni single atoms as a high-performance electrocatalyst for the hydrazine oxidation reaction. Adv Mater. 2022;34(36):2204388. doi:10.1002/adma.202204388.
  52. 52.
    Wang S, Song C, Cai Y, Li Y, Jiang P, Li H, Interfacial polarization triggered by covalent-bonded MXene and black phosphorus for enhanced electrochemical nitrate to ammonia conversion. Adv Energy Mater. 2023;13(31):2301136. doi:10.1002/aenm.202301136.
  53. 53.
    Cai J, Huang J, Cao A, Wei Y, Wang H, Li X, Interfacial hydrogen bonding-involved electrocatalytic ammonia synthesis on OH-terminated MXene. Appl Catal B. 2023;328: 122473. doi:10.1016/j.apcatb.2023.122473.
  54. 54.
    Ingavale S, Marbaniang P, Palabathuni M, Mishra N. In situ growth of copper oxide on MXene by combustion method for electrochemical ammonia production from nitrate. Nanoscale Adv. 2024;6(2):481–488. doi:10.1039/d3na00609c.
  55. 55.
    Zhou Y, Duan R, Li H, Zhao M, Ding C, Li C. Boosting electrocatalytic nitrate reduction to ammonia via promoting water dissociation. ACS Catal. 2023;13(16):10846–10854. doi:10.1021/acscatal.3c02951.
  56. 56.
    Yu J, Qin Y, Wang X, Zheng H, Gao K, Yang H, Boosting electrochemical nitrate-ammonia conversion via organic ligands-tuned proton transfer. Nano Energy. 2022;103: 107705. doi:10.1016/j.nanoen.2022.107705.
  57. 57.
    Kim K, Zagalskaya A, Ng JL, Hong J, Alexandrov V, Pham TA, Coupling nitrate capture with ammonia production through bifunctional redox-electrodes. Nat Commun. 2023;14(1):1–13. doi:10.1038/s41467-023-36318-1.
  58. 58.
    Olad A, Farshi F, Ettehadi J. Electrocatalytic reduction of nitrate ions from water using polyaniline nanofibers modified gold electrode. Water Environ Res. 2012;84(2):144–149. doi:10.2175/106143011x13225991083604.
  59. 59.
    Tao W, Wang P, Li H, Huang R, Zhou G. Engineering sulfur vacancies optimization in Ni3Co6S8 nanospheres toward extraordinarily efficient nitrate electroreduction to ammonia. Appl Catal B. 2023;324: 122193. doi:10.1016/j.apcatb.2022.122193.
  60. 60.
    Fan K, Xie W, Li J, Sun Y, Xu P, Tang Y, Active hydrogen boosts electrochemical nitrate reduction to ammonia. Nat Commun. 2022;13(1):1–13. doi:10.1038/s41467-022-35664-w.
  61. 61.
    Hu T, Wang C, Wang M, Li CM, Guo C. Theoretical insights into superior nitrate reduction to ammonia performance of copper catalysts. ACS Catal. 2021;11(23):14417–14427. doi:10.1021/acscatal.1c03666.
  62. 62.
    Fu W, Hu Z, Du Y, Su P, Su Y, Zhang Q, Building dual active sites Co3O4/Cu electrode to break scaling relations for enhancement of electrochemical reduction of nitrate to high-value ammonia. J Hazard Mater. 2022;434: 128887. doi:10.1016/j.jhazmat.2022.128887.
  63. 63.
    Xue Y, Yu Q, Ma Q, Chen Y, Zhang C, Teng W, Electrocatalytic hydrogenation boosts reduction of nitrate to ammonia over single-atom Cu with Cu(I)-N3C1 sites. Environ Sci Technol. 2022;56(20):14797–14807. doi:10.1021/acs.est.2c04456.
  64. 64.
    Huang S, Wang A, Dong X-Y, Li J-K, Meng Y, Song J-L. In-situ scalable fast fabrication of Cu-Cu2+1O nanorods for highly efficient electrocatalytic reduction into ammonia under neutral medium. J Mater Sci Technol. 2023;155: 111–118. doi:10.1016/j.jmst.2023.02.008.
  65. 65.
    Cai J, Wei Y, Cao A, Huang J, Jiang Z, Lu S, Electrocatalytic nitrate-to-ammonia conversion with ∼100% Faradaic efficiency via single-atom alloying. Appl Catal B. 2022;316: 121683. doi:10.1016/j.apcatb.2022.121683.
  66. 66.
    Wang J, Wang Y, Cai C, Liu Y, Wu D, Wang M, Cu-doped iron oxide for the efficient electrocatalytic nitrate reduction reaction. Nano Lett. 2022;23(5):1897–1903. doi:10.1021/acs.nanolett.2c04949.
  67. 67.
    Cerrón-Calle GA, Wines A, Garcia-Segura S. Atomic hydrogen provision by cobalt sites in a bimetallic Ni/Co(OH)x and trimetallic Ni/Cu2O/Co(OH)x configurations for superior ammonia production. Appl Catal B. 2023;328: 122540. doi:10.1016/j.apcatb.2023.122540.
  68. 68.
    Cheng X, He J, Ji H, Zhang H, Cao Q, Sun W, Coordination symmetry breaking of single-atom catalysts for robust and efficient nitrate electroreduction to ammonia. Adv Mater. 2022;34(36):2205767. doi:10.1002/adma.202205767.
  69. 69.
    Li B, Xue P, Bai Y, Tang Q, Qiao M, Zhu D. Coupling Cu doping and oxygen vacancies in Co3O4 for efficient electrochemical nitrate conversion to ammonia. Chem Commun. 2023;59(34):5086–5089. doi:10.1039/D3CC00864A.
  70. 70.
    Liu P, Yan J, Huang H, Song W. Cu/Co bimetallic conductive MOFs: electronic modulation for enhanced nitrate reduction to ammonia. Chem Eng J. 2023;466: 143134. doi:10.1016/j.cej.2023.143134.
  71. 71.
    Xu Y, Wen Y, Ren T, Yu H, Deng K, Wang Z, Engineering the surface chemical microenvironment over CuO nanowire arrays by polyaniline modification for efficient ammonia electrosynthesis from nitrate. Appl Catal B. 2023;320: 121981. doi:10.1016/j.apcatb.2022.121981.
  72. 72.
    Fu W, Du Y, Jing J, Fu C, Zhou M. Highly selective nitrate reduction to ammonia on CoO/Cu foam via constructing interfacial electric field to tune adsorption of reactants. Appl Catal B. 2023;324: 122201. doi:10.1016/j.apcatb.2022.122201.
  73. 73.
    Zhao X, Geng Q, Dong F, Zhao K, Chen S, Yu H, Boosting the selectivity and efficiency of nitrate reduction to ammonia with a single-atom Cu electrocatalyst. Chem Eng J. 2023;466: 143314. doi:10.1016/j.cej.2023.143314.
  74. 74.
    Ren T, Yu Z, Yu H, Deng K, Wang Z, Li X, Interfacial polarization in metal-organic framework reconstructed Cu/Pd/CuOx multi-phase heterostructures for electrocatalytic nitrate reduction to ammonia. Appl Catal B. 2022;318: 121805. doi:10.1016/j.apcatb.2022.121805.
  75. 75.
    Cui Y, Dong A, Zhou Y, Qu Y, Zhao M, Wang Z, Interfacially engineered nanoporous Cu/MnOx hybrids for highly efficient electrochemical ammonia synthesis via nitrate reduction. Small. 2023;2207661. doi:10.1002/SMLL.202207661.
  76. 76.
    Chavez ME, Biset-Peiró M, Murcia-López S, Morante JR. Cu2O-Cu@Titanium surface with synergistic performance for nitrate-to-ammonia electrochemical reduction. ACS Sustain Chem Eng. 2023;11(9):3633–3643. doi:10.1021/acssuschemeng.2c05885.
  77. 77.
    Liu H, Lang X, Zhu C, Timoshenko J, Rüscher M, Bai L, Efficient electrochemical nitrate reduction to ammonia with copper-supported rhodium cluster and single-atom catalysts. Angew Chem Int Ed. 2022;61(23):e202202556. doi:10.1002/ANIE.202202556.
  78. 78.
    Fu X, Zhao X, Hu X, He K, Yu Y, Li T, Alternative route for electrochemical ammonia synthesis by reduction of nitrate on copper nanosheets. Appl Mater Today. 2020;19: 100620. doi:10.1016/J.APMT.2020.100620.
  79. 79.
    Zhao X, Jia X, Zhang H, Zhou X, Chen X, Wang H, Atom-dispersed copper and nano-palladium in the boron-carbon-nitrogen matric cooperate to realize the efficient purification of nitrate wastewater and the electrochemical synthesis of ammonia. J Hazard Mater. 2022;434: 128909. doi:10.1016/j.jhazmat.2022.128909.
  80. 80.
    Xu M, Xie Q, Duan D, Zhang Y, Zhou Y, Zhou H, Atomically dispersed Cu sites on dual-mesoporous N-doped carbon for efficient ammonia electrosynthesis from nitrate. ChemSusChem. 2022;15(11):e202200231. doi:10.1002/cssc.202200231.
  81. 81.
    Niu Z, Fan S, Li X, Wang P, Liu Z, Wang J, Bifunctional copper-cobalt spinel electrocatalysts for efficient tandem-like nitrate reduction to ammonia. Chem Eng J. 2022;450: 138343. doi:10.1016/j.cej.2022.138343.
  82. 82.
    Wang Z, Sun C, Bai X, Wang Z, Yu X, Tong X, Facile synthesis of carbon nanobelts decorated with Cu and Pd for nitrate electroreduction to ammonia. ACS Appl Mater Interfaces. 2022;14(27):30969–30978. doi:10.1021/acsami.2c09357.
  83. 83.
    Akram MA, Zhu B, Cai J, Qin S, Hou X, Jin P, Hierarchical nanospheres with polycrystalline Ir&Cu and amorphous Cu2O toward energy-efficient nitrate electrolysis to ammonia. Small. 2023;19(15):2206966. doi:10.1002/smll.202206966.
  84. 84.
    Shen Z, Yu Y, Zhao Z, Zhang S, Xu S, Yang S, Highly distributed amorphous copper catalyst for efficient ammonia electrosynthesis from nitrate. J Hazard Mater. 2023;445: 130651. doi:10.1016/j.jhazmat.2022.130651.

Written by

Thi Kim Cuong Phu, Phi Long Nguyen, Thi Viet Bac Phung, Phuoc-Anh Le

Article Type: Mini-review

•

Date of acceptance: July 2024

Date of publication: August 2024

•

DOI: 10.5772/geet.32

Copyright: The Author(s), Licensee IntechOpen, License: CC BY 4.0

Download for free

© The Author(s) 2024. Licensee IntechOpen. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0/), which permits unrestricted reuse, distribution, and reproduction in any medium, provided the original work is properly cited.

Impact of this article

115

Downloads

287

Views

1

Altmetric Score

Share this article

Join us today!

Submit your Article