Electrocatalytic Nitrogen Fixation Research Articles

Unveiling F-coordination tuning of dense Fe-N4 active sites via nitrogen fixation over advanced electrocatalysts

The manuscript presents a significant advancement in the field of electrocatalytic nitrogen fixation by unveiling the role of fluorine coordination in tuning the activity of atomically dispersed iron-nitrogen (Fe-N4) active sites within porous carbon (PC). The innovative approach employs chemical vapor deposition (CVD) to fabricate F-Fe-NC active sites, which, upon fluorination, modulate the electronic configuration of iron, enhancing nitrogen adsorption and activation. The F-Fe-NC catalyst demonstrated a remarkable enhancement in electrocatalytic nitrogen reduction reaction (NRR) performance, achieving an ammonia yield rate (RNH3) of 125.49 μg h−1 mgcat.−1 and a Faradaic efficiency (FE) of 25.19 %. In-situ electrochemical mass spectrometry and Density Functional Theory (DFT) calculations were utilized to dissect the NRR kinetics and elucidate the underlying reaction mechanism, identifying the potential-determining step. The study introduces a novel, high-performance catalyst for electrocatalytic NRR and provides a practical strategy for optimizing the active-site microenvironment, laying the groundwork for the future commercial application of electrocatalytic NRR processes.

Solar-driven photocatalytic nitrogen fixation on transition metal-doped covalent organic frameworks: First-principles study

Designing highly efficient single-atom catalysts for converting nitrogen into ammonia under ambient temperature conditions holds significant importance. Current research predominantly focuses on electrocatalytic nitrogen fixation, but compared to that, photocatalytic nitrogen fixation requires only sunlight as an energy source, making it more environmentally friendly and cost-effective. Developing efficient nitrogen reduction reaction (NRR) photocatalysts presents a promising yet highly challenging task. Two-dimensional (2D) covalent organic frameworks (COFs) have garnered interest because of their elevated surface area and regular pore structure. This study employs density functional theory calculations to investigate the potential of NRR photocatalysts using the 2D COF TMT-TFPT-COF (TT-COF) supported with 18 different transition metal atoms (TM = Rh, Nb, Os, Mo, Ru, Pt, Ni, Co, V, Cu, Fe, Re, W, Cr, Ta, Mn, Pd, Ti). Through a four-step selection process, the most promising photocatalyst is identified. The results indicate that a single Re atom loaded onto TT-COF (Re@TT-COF) displays the optimal nitrogen fixation performance, demonstrating excellent catalytic activity and selectivity with a limiting potential of only −0.30 V. Furthermore, its good light absorption efficiency, suitable band edge position, and significant photo-generated electron potential enable spontaneous nitrogen fixation. Our study provides useful guidance for the rational design of COF-based NRR photocatalysts with high activity, stability, and selectivity.

Understanding the Intrinsic Mechanism of High‐Performance Electrocatalytic Nitrogen Fixation by Heterogenization of Homonuclear Dual‐Atom Catalysts

Understanding the Intrinsic Mechanism of High‐Performance Electrocatalytic Nitrogen Fixation by Heterogenization of Homonuclear Dual‐Atom Catalysts

MIL-101(Fe) supported Au-Cu nanoalloy for enhanced electrochemical nitrogen fixation in gas–liquid-solid three-phase reactor

Low-temperature electrocatalytic nitrogen fixation technology is a green artificial nitrogen fixation technology. Here, we designed and synthesized AuxCuy/MIL-101 series catalysts, i.e., using simple alloy engineering strategy, the synthesized AuCu nanoalloy particles were efficiently loaded onto MIL-101(Fe) by one-step co-reduction. Experiments and calculations show that (Ⅰ) MIL-101(Fe) as support not only enhances the N2 enrichment ability of catalysts, but also facilitates the high dispersion of AuCu nanoparticles. (II) In AuCu nanoalloy, the strong coupling between Au-Cu sites bridges its effective electron transfer, improves the charge structure of Au sites, thereby enhancing the Au 5d-N2 π* interaction, which not only facilitates the adsorption of N2 by catalysts, but also weakens the N≡N triple bond and reduces RDS (N2 → NNH*, 0.38 eV). (III) Au-Cu alloying increases the hydrogen adsorption free energy (0.76 eV), which weakens the competitive adsorption between H+ and N2 by catalysts, and optimizes the charge transfer efficiency of AuxCuy/MIL-101 catalysts. Therefore, the overall NH3 yield and FE of AuxCuy/MIL-101 catalysts are higher than those of MIL-101, Cu/MIL-101 and Au/MIL-101. After optimization, Au1Cu1/MIL-101 with the highest ECSA and suitable Rct has the highest NRR activity (NH3 yield: 161.07 μg h−1 mg-1cat., FE: 58.86 %), which exceeds most Au-based catalysts. Meanwhile, the in-situ FTIR test results further indicate that Au-Cu alloying can accelerate the cleavage of N≡N and the adsorption of N2 by catalysts. This study demonstrates that the gold-copper alloying strategy not only promotes Au 5d feedback to N≡N bond, reduces RDS but also increases ΔGH*, inhibits proton adsorption, ultimately promoting Au1Cu1/MIL-101 catalyst to perform highly efficient NRR performance.

Boosting electrocatalytic nitrogen fixation on Ni-P codoped MoS2 nanosheets

Electrocatalytic nitrogen fixation in an aqueous solution is considered a promising approach to ammonia synthesis. Still, this process has low Faraday efficiency and ammonia yield, so it is necessary to develop an efficient, clean, and safe catalyst to promote nitrogen reduction process. Doping can be easily carried out during the crystal growth owing to the weak interaction between the sandwiched layers (due to van der Waals forces) of MoS2. Here, a Ni-P codoped MoS2 nanosheets is designed as a highly efficient catalyst for electrochemical nitrogen fixation with superior selectivity. Especially, the doping of Ni achieved the transformation of MoS2 from 2 H phase to 1 T phase, improving the conductivity of the material. In addition, the doping of P creates more sulfur vacancies in the catalyst, thereby producing more H*, which promotes the adsorption and activation of nitrogen. The as-synthesized Ni-P codoped MoS2 nanosheets show excellent catalytic performance with a high yield of electrocatalytic ammonia synthesis (84.29 μgNH3 h−1 mgcat−1) and Faraday efficiency (2.39 %) at −0.5 V versus reversible hydrogen electrode in acidic electrolytes (0.005 M H2SO4), which outperformed most electrocatalytic ammonia synthesis catalysts. Furthermore, the Ni-P codoped MoS2 catalyst also shows outstanding electrochemical stability and durability. This work may offer a hopeful lead for designing effective non-noble-metal NRR electrocatalysts.

Directional design of the pyridine ligand functional block fine-tuned hydrophobicity to improve the electrocatalytic nitrogen fixation performance of the Co/Ni based MOFs-derived materials

A series of isostructural Co/Ni-MOFs with different linearly bridged bipyridines as organic linkers has been designed and synthesized. Experimental studies reveal that linker engineering by tuning the functional block of the pyridine-bridging units renders these MOFs derived materials with significantly improved electrocatalytic nitrogen reduction reactions (eNRR) to NH3. Among them, at −0.4 V vs reversible hydrogen electrode the one containing a 1,3,4-thiadiazole unit exhibits the best eNRR performance in 0.1 M Na2SO4 with the highest NH3 yield (39.7 μg h−1 mg−1) and Faraday efficiency (33.3 %). This excellent nitrogen fixation performance comes from the synergistic effect of the heterojunction formed by the Co2N component that is conducive to nitrogen fixation and the Co9S8 component that inhibits hydrogen evolution in the derived material. Significantly, the systematic tuning of the bridging ligands in MOFs provides a new pathway to develop eNRR electrocatalysts.

Constructing diatomic catalyst on MoSSe achieves ultra-low overpotential for nitrogen fixation: First-principles study

The collaborative interaction between the diatoms can enhance the catalytic activity of the transition metal atoms and facilitate the activation of nitrogen molecules. Based on first-principles calculations, the feasibility of electrocatalytic nitrogen fixation as a diatomic catalyst (TMs@MoSSe) formed by transition metal dimers (V, Cr, Mn, Fe, Co, and Ni) dispersed on a two-dimensional Janus MoSSe monolayer is systematically investigated. The results demonstrate that the MoSSe monolayer loaded with double chromium atoms (Cr2@MoSSe) exhibits exceptional catalytic activity, showcasing an extremely low overpotential of 0.17 V in the enzymatic mechanism. Specifically, this research elucidates the nitrogen reduction capacity of the electrocatalyst by considering its magnetic moment and work function, concluding that a lower work function corresponds to enhanced catalytic activity. Additionally, the product of the magnetic moment and valence electron numbers of the transition metal atoms (μTM⋅dTM) exhibits an inverted volcano relationship with the overpotential. These findings can provide valuable insights for the design of diatomic catalysts.

Jahn–Teller Distortions Induced by in situ Li Migration in λ‐MnO2 for Boosting Electrocatalytic Nitrogen Fixation

AbstractLithium‐mediated electrochemical nitrogen reduction reaction (Li‐NRR) completely eschews the competitive hydrogen evolution reaction (HER) occurred in aqueous system, whereas the continuous deposition of lithium readily blocks the active sites and further reduces the reaction kinetics. Herein, we propose an innovative in situ Li migration strategy to realize that Li substitutes Mn sites in λ‐MnO2 instead of evolving into the dead Li. Comprehensive characterizations corroborate that the intercalation of Li+ at high voltage breaks the structural integrity of MnO6 octahedron and further triggers unique Jahn–Teller distortions, which promotes the spin state regulation of Mn sites to generate the ameliorative eg orbital configuration and accelerates N≡N bond cleavage via eg‐σ and eg‐π* interaction. To this end, the resulted cationic disordered LiMnO4 delivers the recorded highest NH3 yield rate of 220 μg h−1 cm−2 and a Faradaic efficiency (FE) 83.80 % in organic electrolyte.

Jahn-Teller Distortions Induced by in situ Li Migration in λ-MnO2 for Boosting Electrocatalytic Nitrogen Fixation.

Lithium-mediated electrochemical nitrogen reduction reaction (Li-NRR) completely eschews the competitive hydrogen evolution reaction (HER) occurred in aqueous system, whereas the continuous deposition of lithium readily blocks the active sites and further reduces the reaction kinetics. Herein, we propose an innovative in situ Li migration strategy to realize that Li substitutes Mn sites in λ-MnO2 instead of evolving into the dead Li. Comprehensive characterizations corroborate that the intercalation of Li+ at high voltage breaks the structural integrity of MnO6 octahedron and further triggers unique Jahn-Teller distortions, which promotes the spin state regulation of Mn sites to generate the ameliorative eg orbital configuration and accelerates N≡N bond cleavage via eg -σ and eg -π* interaction. To this end, the resulted cationic disordered LiMnO4 delivers the recorded highest NH3 yield rate of 220 μg h-1 cm-2 and a Faradaic efficiency (FE) 83.80 % in organic electrolyte.

A bifunctional nanoporous gold–copper@ZIF film for highly efficient nitrogen electro-fixation

This work presents a unique electrocatalyst made of nanoporous AuCu alloys incorporated in a ZIF-71 film with bifunctional catalytic performance for electrocatalytic nitrogen fixation.

Strategic design of VO2 encased in N-doped carbon as an efficient electrocatalyst for the nitrogen reduction reaction in neutral and acidic media.

Electrocatalytic nitrogen fixation to ammonia (NH3), a precursor for fertilizer production and a promising energy carrier, has garnered widespread interest as an environment-friendly and sustainable alternative to the energy-intensive fossil-feedstock-dependent Haber-Bosch process. The large-scale deployment of this process is contingent on the identification of inexpensive, Earth-abundant systems that can operate efficiently, irrespective of the electrolyte pH for the selective production of NH3. In this regard, we discuss the scalable synthesis of VO2 anchored on N-doped carbon (VO2@CN), and its applicability as a robust electrocatalyst for the nitrogen reduction reaction (NRR). Benefitting from the presence of exposed VO2, which presumably acts as the active site for nitrogen reduction, and its activity over a broad pH range (from acidic to neutral), VO2@CN exhibits a high NH3 yield of 0.31 and 0.52 μmol h-1 mgcat-1 and a maximum Faradaic efficiency (FE) of 67.9% and 61.9% at -0.1 V vs. RHE, under neutral and acidic conditions, respectively. The obscured reaction intermediates of the NRR were identified from in situ ATR-IR studies under both electrolyte conditions. Additionally, the high selectivity of the catalyst was ascertained from the absence of hydrazine production and the competing hydrogen evolution reaction (HER). However, ammonia production underwent a reduction over 12 h of continuous operation presumably owing to the leaching of catalyst under these electrolysis conditions, which was more pronounced in electrolytes with acidic pH. Overall, the present report unveils the performance of an earth-abundant vanadium oxide-based system as an efficient electrocatalyst for the NRR under acidic and neutral pH conditions.

Increasing Mo5+ in M-doped La2(MoO4)3 (M = Fe, Co, Ni, Cu, and Zn) toward efficient electrocatalytic nitrogen fixation

The scheme of M (M = Fe, Co, Ni, Cu, and Zn) doped-La2(MoO4)3 are performed NRR.

Coordination Engineering of Heteronuclear Fe-Mo Dual-Atom Catalyst for Promoted Electrocatalytic Nitrogen Fixation: A DFT Study.

Developing efficient nanostructured electrocatalysts for N2 reduction to NH3 under mild conditions remains a major challenge. The Fe-Mo cofactor serves as the archetypal active site in nitrogenase. Inspired by nitrogenase, we designed a series of heteronuclear dual-atom catalysts (DACs) labeled as FeMoN6-a Xa (a=1, 2, 3; X=B, C, O, S) anchored on the pore of g-C3 N4 to probe the impact of coordination on FeMo-catalyzed nitrogen fixation. The stability, reaction paths, activity, and selectivity of 12 different FeMoN6-a Xa DACs have been systematically studied using density functional theory. Of these, four DACs (FeMoN5 B1 , FeMoN5 O1 , FeMoN4 O2 , and FeMoN3 C3 ) displayed promising nitrogen reduction reaction (NRR) performance. Notably, FeMoN5 O1 stands out with an ultralow limiting potential of -0.11 V and high selectivity. Analysis of the density of states and charge/spin changes shows FeMoN5 O1 's high activity arises from optimal N2 binding on Fe initially and synergy of the FeMo dimer enabling protonation in NRR. This work contributes to the advancement of rational design for efficient NRR catalysts by regulating atomic coordination environments.

D-band center modulation of B-mediated FeS2 to activate molecular nitrogen for electrocatalytic ammonia synthesis

Electrocatalytic nitrogen fixation is a promising approach for ambient ammonia synthesis. The key that limits the improvement of ammonia evolution performance is the NN bond cleavage of molecular nitrogen. One effective route to break this bottleneck is the d-band center modulation of catalysts. Herein, a nonmetal boron mediated FeS2 (B-FeS2) is developed for electrocatalytic nitrogen fixation. The B-mediation alters the spin-orbits of Fe site and upshifts the d-band center of FeS2, thus inducing a strong d-π* interaction between the Fe site and nitrogen to activate NN bond. Besides, the experimental and theoretical calculations indicate the B-mediation reduces the energy barrier for *NNH intermediate, thus significantly accelerating ammonia production. As a result, B-FeS2 displays high ammonia yield (1.56 mmol·g−1·h−1) with 12.6 % Faradaic efficiency. This strategy of d-band center tuning induced by the B-mediation provides a distinctive insight for the design of high-efficiency electrocatalysts.

Design of novel transition metal doped pyrazine-modified graphyne as highly effective electrocatalysts for nitrogen fixation

The production of ammonia consumes plenty of energy every year, so it is crucial to develop efficient and sustainable methods of electrocatalytic ammonia synthesis. Although some materials have shown high catalytic activity for nitrogen reduction reaction (NRR), searching for catalytic materials with excellent electrical properties is still a promising topic. Graphyne and its family are well suited as catalysts due to their high electrical conductivity and carrier mobility. In this paper, we have systematically studied the catalytic properties of transition metal atoms anchored on pyrazine-modified graphyne (pyGY) for NRR by density functional theory calculations. Through a series of scanning procedures, Nb, Mo and W-pyGYs are found to be excellent catalysts for electrocatalytic NRR with limiting potentials of − 0.43 V, − 0.36 V, and − 0.46 V, respectively. Moreover, solvation effects are considered and the lowering effect of solvent on the limiting potential is revealed. In addition, the mechanism of superior catalytic activity is explored from an electronic perspective. Finally, two descriptors related to electronegativity and valence electron number are selected to clarify the trend of NRR activity. The volcano diagram trends of NN bond length, Gibbs free energy change in the first hydrogenation step and limiting potential are revealed. This work provides a reliable method for screening efficient electrocatalytic nitrogen fixation catalysts.

Defective SiC nanotube based single-atom catalysts for electrocatalytic nitrogen fixation with curvature effect

The production of fertilizers, explosives, and various other chemicals relies heavily on ammonia (NH3). Electrochemical reduction of nitrogen to ammonia, also known as the nitrogen reduction reaction (NRR), is a potential alternative to the Haber-Bosch process that can be carried out at ambient conditions. However, many NRR catalysts suffer from low selectivity and require a large overpotential to drive the reaction, limiting their practical application. In this study, we used density functional theory (DFT) calculations to investigate the mechanistic aspects of the NRR and the effect of curvature variation on the catalytic activity of silicon carbide nanotubes (SiCNTs) decorated with 3d-5d transition metal single-atom catalysts. Our results suggest that the Os@SiCNT catalyst exhibits promising activity as an eNRR catalyst with an overpotential of 0.47 V and high selectivity over hydrogen evolution reaction (HER) competition. The electronic “acceptance-donation” interaction between N2 and Os promotes the adsorption and activation of N2 molecules on the catalyst surface. Additionally, our findings demonstrate that as the nanotube diameter decreases, the energy barrier for the NRR reaction decreases as well. However, this decrease in diameter also leads to a weaker capacity for *N2 adsorption, which may ultimately reduce the selectivity of the NRR reaction. These findings offer valuable insights that can aid in the rational design of nanotube-based electrocatalysts for eNRR.

Microfluidic Tailoring of a Ru Nanodots/Carbon Heterocatalyst for Electrocatalytic Nitrogen Fixation

Microfluidic Tailoring of a Ru Nanodots/Carbon Heterocatalyst for Electrocatalytic Nitrogen Fixation

·H effectively enhance electrocatalytic nitrogen fixation

Nowadays, most reported ammonia (NH3) yields and Faradaic efficiency (FE) of electrocatalysts are very low in the field of electrocatalytic nitrogen reduction reactions (NRR). Here, we are reported ·H for the first time in the field of electrocatalytic NRR, which are generated by sulfite (SO32−) and H2O in electrolyte solutions upon exposure to UV light. The high NH3 yields can achieve 100.7 μg h−1 mgcat−1, while stability can achieve 64 h and the FE can achieve 27.1% at −0.3 V (vs. RHE) with UV irradiation. In situ Fourier transform infrared spectroscopy (FTIR), electron spin resonance (ESR), density functional theory (DFT) and 1H nuclear magnetic resonance (NMR) tests showed that the ∙H effectively lowered the reaction energy barrier at each step of the NRR process and inhibits the occurrence of competitive hydrogen evolution reaction (HER). This explores the path and provides ideas for the field of electrocatalysis involving water.

Bread from air (and electricity): producing ammonia at the interface of porous carbons and room-temperature salt melts

Bread from air (and electricity): producing ammonia at the interface of porous carbons and room-temperature salt melts The ERC Starting Grant project "Nanocarbon-Ionic Liquid-Interfaces for Catalytic Activation of Nitrogen" (CILCat) aims to establish a novel principle in catalysis that holds holistic perspectives for the activation of small molecules within electric double-layers formed between ionic liquids and nanostructured carbon materials. The electrocatalytic nitrogen fixation will serve as a model reaction at the beginning.

Theoretical screening and investigation on electrocatalytic nitrogen fixation of single transition metal atom supported by monolayer SnS2

Dispersing transition metal atoms on substrates is a novel approach to constructing (photo) electrocatalysts, which has received extensive attention in electrocatalytic nitrogen reduction reaction (NRR). Two-dimensional monolayer SnS2 is an easy-to-prepare, low-cost, and low-environmental pollution material. In this work, through first-principles calculation, fifteen transition metal atoms (TM = Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zr, Mo, Ru, Hf, Ta, W, Os) supported on monolayer SnS2 (TM@SnS2), respectively, are investigated as an efficient NRR catalyst. The screening of the NRR catalyst is followed by a three-step method and our results indicate that a single W atom supported on top of the Sn atom of SnS2 (W@SnS2) has the best catalytic activity, with an over potential of 0.42 V along the distal pathway, which is much lower than the reported values based on SnS2. Moreover, the N2 adsorption on W@SnS2 is far superior to the hydrogen atom adsorption, which can inhibit the competitive side reaction effectively. Our results are helpful for the design of NRR catalysts based on SnS2 monolayer.