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Article

Using a Single-Atom FeN4 Catalyst on Defective Graphene for the Efficient Reduction of NO to Alanine: A Computational Study

by
Yu Tian
1,2,
Xiaoxi Yuan
2,
Zexuan Guo
2,
Jingyao Liu
1,*,
Tingting Zhao
3,* and
Zhongmin Su
1
1
Institute of Theoretical Chemistry, College of Chemistry, Jilin University, Changchun 130023, China
2
Jilin Engineering Laboratory for Quantum Information Technology, Institute for Interdisciplinary Quantum Information Technology, Jilin Engineering Normal University, Changchun 130052, China
3
School of Chemistry and Chemical Engineering, Changsha University of Science and Technology, Changsha 410114, China
*
Authors to whom correspondence should be addressed.
Catalysts 2024, 14(12), 876; https://doi.org/10.3390/catal14120876
Submission received: 7 November 2024 / Revised: 27 November 2024 / Accepted: 27 November 2024 / Published: 30 November 2024
(This article belongs to the Special Issue Sustainable Catalysis for Green Chemistry and Energy Transition)
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Abstract

:
The use of a single-atom FeN4 catalyst on defective graphene (Fe-NC) has recently emerged as an effective method for the synthesis of amino acids. Herein, we investigated the mechanism of alanine formation on FeN4-doped graphene using comprehensive density functional theory (DFT) computations. The alanine formation reaction begins with the activation of NO molecules on the surface, followed by their reaction with hydrogen atoms provided in the system. The computational results show that NO molecules can be effectively activated on Fe-NC, facilitating the subsequent alanine formation at a relatively lower potential. The potential-limiting step in alanine production involves either the formation of HNO* or HNOH* intermediates on Fe-NG, as the free energy changes (ΔG) in these two elementary steps are nearly equivalent. Notably, the formation of HNO* exhibits a higher activation energy (Ea) compared to HNOH* formation. This study provides valuable insights into the C–N coupling reaction and the mechanism of amino acid synthesis on single-atom catalysts.

Graphical Abstract

1. Introduction

As human demand for nitrogen-based compounds has increased, anthropogenic nitrogen fixation has become a critical area of research [1]. The Haber–Bosch process, one of the most important industrial inventions, enables large-scale nitrogen fixation. However, the process requires extreme conditions due to the high stability of the N≡N bond (941 kJ mol−1), leading to significant energy consumption [2,3]. Consequently, considerable efforts have been made to optimize nitrogen reduction processes and reduce energy demands [4].
One promising alternative is the utilization of nitrogen oxides (NOx) as nitrogen sources for fixation. NOx compounds, such as nitric oxide (NO) and nitrogen dioxide (NO2), possess weaker bonds compared to N2 and are generated as pollutants during fossil fuel combustion, making them attractive targets for simultaneous nitrogen fixation and environmental remediation [5,6,7]. Recent advancements in electrocatalysis have demonstrated the potential of electrochemical NOx reduction to synthesize valuable chemicals such as ammonia (NH3), hydrazine (N2H4), and hydroxylamine (H2NOH), which are of great industrial significance [8,9,10,11,12,13,14,15,16]. Transforming harmful NOx into these value-added products not only mitigates environmental pollution but also creates economic opportunities. However, synthesizing more complex nitrogen-containing compounds, particularly those involving nitrogen–heteroatom bonds (e.g., N–C and N–N bonds), remains a significant challenge [17,18].
Electrochemical methods have shown promise in facilitating nitrogen–heteroatom bond formation, enabling the production of high-value compounds such as urea, oximes, amides, and amino acids, which are critical in various industries. Transition metal catalysts, especially single-atom catalysts (SACs), have attracted significant attention due to their high efficiency and minimal metal usage [19,20,21]. Among these, transition metals dispersed on nitrogen-doped carbon materials (M-NC) have emerged as highly active catalysts, often surpassing the performance of traditional catalytic systems [22,23,24]. Notably, Jiao and co-workers pioneered the electrochemical C–N coupling process using M-NC catalysts [25]. Since then, this strategy has been successfully applied to synthesize several complex nitrogen-containing compounds, including amino acids, highlighting its potential for both environmental remediation and sustainable chemical production [26,27,28,29,30].
Amino acids are particularly important for biological growth and various industrial applications [31,32]. However, the complexity of current synthesis methods has limited their widespread use [33,34,35,36]. Efforts to simplify amino acid synthesis have led to the development of catalytic systems using cobalt, silver, and copper complexes [37]. Recently, Zhang and co-workers reported the silver (Ag)-catalyzed synthesis of amino acids using nitric oxide (NO) as the nitrogen source [38]. The use of atomical iron (Fe) dispersed on N-doped bulk graphite for the electrocatalyzed synthesis of amino acids has been proposed by Li and co-workers [39]. Compared to Ag, the Fe-catalyzed synthesis of amino acids is more interesting for us because (i) atomically dispersed Fe-based catalysts were used for C–N bond formation, (ii) nitric oxide (NO) was used as the substrate, and other nitrogen sources such as NO3− and NO2 are also useful for synthetic chemistry, and (iii) Fe is widely used as a catalyst in many reactions due to its low cost and low toxicity [40].
Encouraged by these studies, we systematically explored the mechanism of amino acid synthesis from NO on single-atom FeN4 moiety on defective graphene (Fe-NG) using density functional theory (DFT) calculations. The catalytic cycle was experimentally proposed [39], and based on this, we presented possible pathways for NO reduction to amino acids, as shown in Scheme 1. This work aims to elucidate the mechanism of an Fe-NG catalyst in the synthesis of amino acids and explore the broader potential application of Fe-based single-atom catalysts in nitrogen chemistry.

2. Results and Discussion

2.1. The Structure and Stability of Fe-NG

Before exploring the pathway of NO reduction reaction on Fe-NG, the geometry of Fe-NG catalyst is briefly discussed here. The fully optimized geometry of Fe-NG is shown in Figure 1a. The single Fe atom prefers to bind with four N atoms, leading to the formation of the Fe–N4 motif. All Fe–N bond distances in Fe-NG are 1.893 Å, and the lattice constant of Fe-NG is 17.200 Å. The adsorbed Fe atoms can be totally incorporated into the surface of NG, and the optimized Fe-NG has a nearly planar geometry (Figure 1a).
The stability of a catalyst is very important to maintain its catalytic activity. The strong interaction between the Fe atom and NG could also ensure the high stability of Fe-NG. The interaction between the Fe atom and NG was evaluated by calculating the binding energy (BE) and the formation energy (Ef) of Fe-NG. The BE of an Fe atom on NG is −10.05 eV, as shown in Table S1. The Ef of Fe-NG is 1.44 eV (Table S1), which is in agreement with the reported results [41]. These results suggest the high thermodynamic stability of Fe-NG. The projected density of states (PDOSs) of Fe-NG was also calculated to obtain further insights into its good stability, as shown in Figure 1b. The d orbital of an Fe atom strongly overlaps with the 2p orbital of an N atom near the Fermi level, indicating the strong interaction between the Fe and the N atom.

2.2. NO Adsorption on Fe-NG

The chemisorption of the NO molecule on the Fe-NG surface is the first critical step for effective NO reduction. Hence, we examined the adsorption of NO on Fe-NG, considering both side-on (NO_s) and end-on configurations (Figure S1). Two kinds of end-on geometries were considered based on the attachment of O and N atoms: (i) O_e, where the O atom of NO is attached to the Fe atom while the N atom is farther from the Fe-NG surface, and (ii) N_e, where the N atom of NO is attached to the Fe atom and the O atom is farther from the surface. We calculated all possible configurations and present the most stable configuration in the main text. The results for other configurations are available in the Supplementary Materials (Figure S2). The calculation results show that the NO molecule preferentially adsorbs on Fe-NG in the N_e configuration, as shown in Figure 2a. Notably, the NO_s configuration was found to be unstable as it reverted to the N_e configuration upon full optimization. The Gibbs energy for NO adsorption on Fe-NG with the N_e configuration is −1.38 eV, and the Fe–N distance is 1.683 Å (Table S2), suggesting a highly energetically favorable chemisorption process. The Bader charge analysis revealed a charge transfer of 0.31 |e| from Fe-NG to the NO molecule, leading to the N–O bond length elongation from 1.169 in the free NO molecule to 1.192 Å in the N_e configuration (Table S2). The above results indicate that the NO can be activated by the Fe-NG catalyst.
To obtain further insights into the interaction between Fe-NG and NO, the charge density difference in the N_e configuration for NO adsorption was calculated to verify the electron transfer between the Fe-NG catalyst and the NO molecule, as shown in Figure 2b. In both the NO and Fe of Fe-NG, charge accumulation and depletion are observed. And the charge redistribution is clearly shown compared to the charge density difference in Fe-NG before and after NO adsorption (Figure S3). In particular, upon the adsorption of the NO molecule, the magnetization of Fe-NG decreases from 2.00 to 1.00, and the magnetization of the NO molecule disappears because of the spin-coupling interaction between the Fe and N atoms. NO molecule activation can be further supported by the strong hybridization observed between the 3d states of Fe and the 2p states of NO, as clearly evident from the density of states analysis (Figure 2c). The above results indicate that the NO molecule was activated on Fe-NG, thus facilitating the subsequent reduction reactions.
In addition, pyruvic acid (PA, CH3COCOOH) is another kind of reactant for the synthesis of alanine. Therefore, the competition adsorption between NO and PA are considered. The binding energy (BE) of NO and PA adsorption on Fe-NG was compared, as shown in Figure S4. The BE of NO and PA on Fe-NG are −2.06 and −0.53 eV, respectively, indicating that NO adsorption on Fe-NG is more favorable. Therefore, the following discussion will focus on the NO hydrogenation reaction on Fe-NG.

2.3. Catalytic Cycle for Alanine Formation on Fe-NG

To elucidate the mechanism for alanine formation, we first investigated the catalytic cycle (Scheme 1) of NO reduction on the Fe-NG catalyst. The alanine formation process involves a seven-proton and seven-electron transfer, and the overall reaction can be described as follows: NO + CH3COCOOH + 7H+ + 7e− → H2NCH3CHCOOH + 2H2O. In this section, the pathways for alanine formation on Fe-NG are discussed.

2.3.1. Hydrogenation and Splitting of NO* Species

According to the above discussion, the N_e structure of NO adsorption was selected for the subsequent reaction calculations. The reaction pathways of NO reduction (NOR) are divided into three potential routes: HNO*, NOH*, and N* + O*. As both the N and O atoms of the adsorbed NO are possible sites to accept the first proton and electron, and formed HNO* and NOH* two different species. Also, the absorbed NO can undergo the dissociation of the N–O bond to N* + O*. The ∆G values for the formation of the HNO*, NOH*, and N* + O* species are 0.33, 0.92, and 4.12 eV, respectively (Figure 3). The N* + O* pathway is first excluded due to its high ∆G value. Further hydrogenation of the HNO* and NOH* intermediates is discussed in the following section.

2.3.2. Alanine Formation on Fe-NG

The reaction pathway for alanine formation on Fe-NG is shown in Figure 4. The formed HNO* and NOH* intermediates can undergo further reduction by interacting with a proton and an electron to form HNOH*. The ∆G values for HNOH* formation via HNO* and NOH* are 0.37 and −0.23 eV, respectively. Further hydrogenation of HNOH* yields H2NOH* with a ∆G of −0.14 eV. The C1 atom of PA then interacts with the N atom of H2NOH*, leading to the formation of a C–N bond. This process occurs in two steps: one H atom binds to the N atom of H2NOH* and interacts with the O2 atom of PA, forming the HNOH:CH3COHCOOH* (HNOH:PA(H)*) species. Then, another H atom, bonded to the N atom of HNOH*, interacts with the O2 atom of PA(H). During this process, the OH group dissociates from PA(H) and combines with one H atom from HNOH* to produce a H2O molecule, while the C–N bond is formed in the NOH-PA_O* species. The ∆G values for HNOH:PA(H)* and NOH-PA_O* formation are 1.08 and −1.10 eV, respectively. The next step involves a proton interacting with the O atom of NOH in NOH-PA_O*, forming N-CH3CCOOH* (N-PA_O*) and another H2O molecule, with a ∆G value of −1.97 eV.
In the subsequent hydrogenation step, a proton can either be added to the C1 or the N atom of N-PA_O*, forming N-CH3CHCOOH* (N-PA(H)_O*) and HN-CH3CCOOH* (HN-PA_O*), respectively. The ∆G values for N-PA(H)_O* and HN-PA_O* formation are 0.84 and −0.15 eV, respectively. This indicates that HN-PA_O* has more favorable thermodynamics. Further steps lead to the formation of alanine through hydrogenation, with both H2N-CH3CCOOH* (H2N-PA_O*) and HN-CH3CHCOOH* (HN-PA(H)_O*) being exothermic with ∆G values of −0.26 eV and −0.20 eV, respectively. Subsequently, the last proton and electron pair react to H2N-PA_O* and HN-PA(H)_O* to form the final product of alanine (H2N-CH3CHCOOH).
To provide a comprehensive analysis, we also computed the vibrational frequencies of key intermediate species. The calculated N–H stretching frequency for NH2OH species are 3396 and 3331 cm−1, which is consistent with the experimentally observed 3300–3500 cm−1 bands. Similarly, the calculated C=N stretching frequency for the NOH-PA_O* moiety is 1523 cm−1, matching closely with the experimental band at 1548 cm−1. These theoretical values confirm the assignment of experimental spectra features and support our conclusion that the C–N bond formation via the NH2OH* attacks the PA molecule. The alignment between the theoretical and experimental results demonstrates the robustness of our computational approach and provides strong evidence for the stability of the proposed intermediate on the Fe-NG catalyst.
The above analysis shows that the ΔG value elementary of the NO* + H+ + e− → HNO* and HNO* + H+ + e− → HNOH* steps is nearly equal. According to the CHE model, the limiting potential (Ulim) is calculated as Ulim = −ΔGPL/e, where ΔGPL is the free energy value of the potential-limiting step. The calculated U for HNO* and HNOH* formation is −0.33 or −0.37 V, respectively. Therefore, HNO* and HNOH* formation is the possible potential-limiting step for the reduction of the NO molecule to form the alanine on Fe-NG.
In order to further verify the potential-determining step, the transition states for HNO* and HNOH* formation on Fe-NG were calculated. The energy profiles for these two elementary steps on Fe-NG are shown in Figure 5. For HCO* formation, the H atom adsorbed on the C atom of Fe-NG to afford NO* + H*. The H atom approached the N atom of NO molecule to afford the HNO* species through the transition state (TS) (Figure 5). The activation energy (Ea) for this reaction is 1.56 eV. For HNOH* formation, the H atom adsorbed on the Fe-NG to afford the HNO* + H*_1 and HNO* + H*_2 species. Starting from HNO* + H*_2, the H atom transfer occurred through a TS to afford HNOH* with an Ea value of 0.45 eV (Figure 5). According to these resuts, we can conclude that HNOH* formation is more favorable.

2.4. Side Reaction Analyses

The NO reduction process is known to produce multiple intermediates, leading to a variety of products. Common byproducts include NH3, H2NOH, and N2H4. The hydrogen evolution reaction (HER) is another competitive process that cannot be ignored in electrocatalysis, as H adsorption on the catalyst surface can block active sites, reducing the faradaic efficiency of NO reduction. During alanine synthesis, NH3 and H2 were detected [39]. Therefore, the pathways for the formation of these byproducts are explored here.

2.4.1. The Hydrogen Evolution Reaction on Fe-NG

The adsorption of hydrogen atoms on the catalyst surface was calculated to evaluate HER activity on Fe-NG. The ΔG value for the HER on Fe-NG is 0.34 eV (Figure 6). The Ulim value for the HER on Fe-NG is −0.34 V, which is comparable to the Ulim value for the formation of alanine (−0.37 V). This indicates that hydrogen formation is inevitable during the alanine process of alanine formation, which is consistent with the experimental results [39]. In addition, choosing the appropriate electrolyte or modifying the electrode is a feasible method to inhibit the effect of the HER.

2.4.2. NH3 Formation on Fe-NG

Ammonia (NH3) is one of the common hydrogenated products of NO reduction. The mechanism for NH3 formation on Fe-NG was investigated according to the pathway in Scheme S1. The free energy profiles and the configuration changes for these pathways are shown in Figure 7. The elementary steps before HNOH* formation were discussed above. The formed HNOH* could either be further protonated to H2NOH* and NH* + H2O with the ΔG of −0.14 and −0.78 eV, respectively. Both the H2NOH* and NH* + H2O species could be formed because these two steps are exothermic. The formed NH* can be further reduced to NH3 after additionally interacting with two protons and electrons. However, the formed H2NOH* could be further protonated to NH2* and higher-order products. The ΔG for NH2* formation is −1.89 eV, indicating that NH2* formation has favorable thermodynamics. Subsequently, NH3 is produced by one proton and electron step exothermic process. The ΔG value for the step of NH2* + H+ + e− → NH3 + * is −0.68 eV. HNOH* formation has the ΔGmax value of 0.37 eV in the process of producing NH3. The Ulim value for NH3 formation on Fe-NG is −0.37 V, which is the same as the Ulim value for alanine formation.
Besides the HNOH hydrogenation pathway, another pathway exists. Once the proton interacts with the O atom of the NOH*, it will form N* + H2O. The N* will be hydrogenated to NH3 by reacting with another three protons and electrons, as shown in Figure S5. In this pathway NOH* formation has the largest ΔG value of 0.92 eV. Therefore, the potential step for this pathway is NO* + H+ + e− → NOH* with the Ulim value of −0.92 V. This Ulim value is larger than that of the HNO* pathway, indicating that the HNO* pathway is more favorable for H2NOH formation on Fe-NG. The above results show that NH3 and H2NOH formation is possible in the process of the synthesis of alanine on Fe-NG.

3. Computational Details

All DFT calculations were performed using the Vienna ab initio simulation package (VASP 5.4.1) [42,43]. The Perdew–Burke–Ernzerh (PBE) exchange-correlation functional with Grimme’s D3 dispersion correction (PBE-D3) was employed [44]. The core–electron interactions were described by projector-augmented wave pseudopotentials [45,46]. A vacuum space in the z direction was set to 20 Å to avoid the periodic interactions between layers. The k-points were sampled using a 5 × 5 × 1 and 9 × 9 × 1 Monkhorst-Pack mesh in geometry optimization and electronic structure computations, respectively. The energy cutoff was set to 500 eV. The convergence criteria for energy and force were 10−5 eV and 0.01 eV Å−1, respectively.
The equation for calculating Ecoh is Ecoh = [EFe-NG − (aEFe + bEC + cEN)]/(a + b + c), where EFe-NG, EC, and EN are the energies of Fe-NG, the C atom, and the N atom, respectively, while a, b, and c denote the numbers of Fe atoms, C atoms, and N atoms, respectively. The BE of the Fe atom on N-doped graphene (NG) was calculated as BE = EFe-NG − ENG − EFe, where EFe-NG, ENG, and EFe are the energies of Fe-NG, the N-doped graphene, and the Fe atom, respectively. The free-energy change (ΔG) in each elementary reaction step on the electrocatalysts was calculated using the computational hydrogen electrode (CHE) model proposed by Nørskov et al. [47,48,49]. The calculation of the transition states (TSs) was performed by using the DMol3 code. Details of the ΔG and TSs calculations are shown in the Supplementary Materials [50,51].

4. Conclusions

The reaction mechanism of alanine formation by the hydrogenation of an NO molecule on Fe-NG was investigated by comprehensively performing DFT calculations. This catalytic reaction occurs mainly via two parts: hydrogenation and C–N coupling. There are two endothermic steps in the hydrogenation process, that is, NO + H+ + e− → HNO* and HNO* + H+ + e− → HNOH*. The potential-limiting step is either HNO* formation or HNOH* formation on Fe-NG because the ΔG value is nearly equal in these two elementary steps. In addition, the alanine formation is accompanied by the formation of H2 byproducts. The limiting potential of H2 formation is similar to that of alanine formation. We hope that our theoretical study can provide some ideas to encourage more researchers to further explore the potential of low-dimensional material as electrocatalysts for the synthesis of amino acids.

Supplementary Materials

The following supporting information can be downloaded at https://www.mdpi.com/article/10.3390/catal14120876/s1, Page S1: Computational methods; Figure S1: The initial structures of NO adsorption on Fe-NG studied in this work; Figure S2. The optimized structures of NO adsorption on Fe-NG studied in this work; Figure S3. A side view of the charge density difference plots for (a) Fe-NG and (b) Fe-NG after NO adsorption. The isosurface value is 0.003 e Å3; Figure S4. Optimized configurations of (a) NO and (b) PA adsorbed on Fe-NG; Figure S5. Gibbs energy changes (in eV) for NH3 formation via the NOH* pathway on Fe-NG. Scheme S1: Catalytic cycle for NH3 formation on Fe-NG. Table S1: Geometric parameters, binding energy (BE), and cohesive energy (Ecoh) of Fe-NG; Table S2: Geometric parameters of NO adsorbed on Fe-NG. References [43,45,52,53] are cited in the Supplementary Materials.

Author Contributions

Conceptualization, Y.T. and J.L.; methodology, Y.T. and X.Y.; software, J.L. and Z.S.; validation, Y.T., X.Y., T.Z. and Z.G.; formal analysis, Y.T. and T.Z.; investigation, Y.T.; resources, Y.T. and J.L.; data curation, Y.T.; writing—original draft preparation, Y.T.; writing—review and editing, J.L. and T.Z.; supervision, J.L. and Z.S.; funding acquisition, Y.T. and J.L. All authors have read and agreed to the published version of the manuscript.

Funding

This work was supported by the National Key Research and Development Program of China (Grant No. 2021YFA1500403), the Program of Science and Technology Development Plan of Jilin Province of China (2301ZYTS306) and the Education Department of Jilin Province (JJKH20230217KJ).

Data Availability Statement

The original contributions presented in this study are included in the article/Supplementary Materials. Further inquiries can be directed to the corresponding authors.

Acknowledgments

We acknowledge the High-Performance Computing Center, Jilin Engineering Normal University, for providing the computational resources used in this work.

Conflicts of Interest

The authors declare no conflicts of interest.

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Catalysts 14 00876 sch001
Scheme 1. Catalytic cycle of NO reduction on Fe-NG.
Scheme 1. Catalytic cycle of NO reduction on Fe-NG.
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Catalysts 14 00876 g001
Figure 1. (a) Optimized structures and (b) partial density of states (PDOS) of Fe-NG.
Figure 1. (a) Optimized structures and (b) partial density of states (PDOS) of Fe-NG.
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Figure 2. (a) The N_e configuration for NO adsorption, (b) the charge density difference plots for NO adsorbed on Fe-NG with an isosurface value of 0.003 e Å3, and (c) the PDOS of NO adsorbed on Fe-NG, where charge accumulation and depletion are plotted in the yellow and blue regions, respectively. The Fermi level is denoted with a black dashed line.
Figure 2. (a) The N_e configuration for NO adsorption, (b) the charge density difference plots for NO adsorbed on Fe-NG with an isosurface value of 0.003 e Å3, and (c) the PDOS of NO adsorbed on Fe-NG, where charge accumulation and depletion are plotted in the yellow and blue regions, respectively. The Fermi level is denoted with a black dashed line.
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Figure 3. Gibbs energy profiles of NO hydrogenation and splitting on Fe-NG. * denotes that the NO reduction intermediates are adsorbed on Fe-NG.
Figure 3. Gibbs energy profiles of NO hydrogenation and splitting on Fe-NG. * denotes that the NO reduction intermediates are adsorbed on Fe-NG.
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Figure 4. Gibbs energy profiles of alanine formation by hydrogenation of NO molecule on Fe-NG. * denotes that the NO reduction intermediates are adsorbed on Fe-NG.
Figure 4. Gibbs energy profiles of alanine formation by hydrogenation of NO molecule on Fe-NG. * denotes that the NO reduction intermediates are adsorbed on Fe-NG.
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Figure 5. Potential energy changes (in eV) with geometry changes in HNO* and HNOH* formation.
Figure 5. Potential energy changes (in eV) with geometry changes in HNO* and HNOH* formation.
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Figure 6. A Gibbs energy diagram of the HER on Fe-NG.
Figure 6. A Gibbs energy diagram of the HER on Fe-NG.
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Figure 7. Gibbs energy changes (in eV) for NH3 formation on Fe-NG. * denotes that the NO reduction intermediates are adsorbed on Fe-NG.
Figure 7. Gibbs energy changes (in eV) for NH3 formation on Fe-NG. * denotes that the NO reduction intermediates are adsorbed on Fe-NG.
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MDPI and ACS Style

Tian, Y.; Yuan, X.; Guo, Z.; Liu, J.; Zhao, T.; Su, Z. Using a Single-Atom FeN4 Catalyst on Defective Graphene for the Efficient Reduction of NO to Alanine: A Computational Study. Catalysts 2024, 14, 876. https://doi.org/10.3390/catal14120876

AMA Style

Tian Y, Yuan X, Guo Z, Liu J, Zhao T, Su Z. Using a Single-Atom FeN4 Catalyst on Defective Graphene for the Efficient Reduction of NO to Alanine: A Computational Study. Catalysts. 2024; 14(12):876. https://doi.org/10.3390/catal14120876

Chicago/Turabian Style

Tian, Yu, Xiaoxi Yuan, Zexuan Guo, Jingyao Liu, Tingting Zhao, and Zhongmin Su. 2024. "Using a Single-Atom FeN4 Catalyst on Defective Graphene for the Efficient Reduction of NO to Alanine: A Computational Study" Catalysts 14, no. 12: 876. https://doi.org/10.3390/catal14120876

APA Style

Tian, Y., Yuan, X., Guo, Z., Liu, J., Zhao, T., & Su, Z. (2024). Using a Single-Atom FeN4 Catalyst on Defective Graphene for the Efficient Reduction of NO to Alanine: A Computational Study. Catalysts, 14(12), 876. https://doi.org/10.3390/catal14120876

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