N2 Activation Research Articles

Bioinspired Dual-Site Photocathode with Atomic Molybdenum and Alkynyl Networks for Scalable Solar Ammonia Synthesis.

The Haber-Bosch process, while pivotal for global ammonia production, remains energy-intensive and environmentally unsustainable. Here, we report a nitrogenase-inspired photocathode (Mo1/HsGDY@Cu2O) that synergistically integrates light-harvesting Cu2O nanowires, hydrogen-radical-generating alkynyl-rich graphdiyne (HsGDY), and atomically dispersed molybdenum sites for solar-driven nitrogen fixation. Mimicking the Fe/MoFe-cofactor collaboration in nitrogenase, the photocathode enables efficient N2 adsorption at Mo1 sites and hydrogen radical transfer from adjacent alkynyl groups, significantly lowering the energy barrier for N2 hydrogenation. Under 10-sun illumination, the system achieves a record ammonia yield of 78.9 μg cm-2 h-1 with a Faradaic efficiency of 38.9% while maintaining 86% activity over 240 h. The ammonia solution directly enhances Epipremnum aureum root growth by 2.3-fold, demonstrating immediate agricultural utility. Combined with bias-free operation and scalable solar concentration, this work provides a practical blueprint for decarbonizing fertilizer production. Operando spectroscopy and DFT calculations further reveal that the dual-site synergy─Mo1 for N2 activation and alkynyl groups for H• supply─drives the catalytic mechanism, offering a universal strategy for enzyme-inspired energy conversion systems.

Predicting σ0π2 Carbene-Mediated Hydroboration and Bis-carbene Functionalization of Dinitrogen.

Although the carbene-catalyzed N2 fixation process had been investigated by scientists for decades prior to borylene species, the interest in the carbene-mediated N2 activation process has drawn less attention than that of borylene species in the past few years, especially unique σ0π2 carbenes. Herein, we demonstrate the important role of unique σ0π2 carbenes in the 1,1-hydroboration and bis-carbene functionalization of N2 using density functional theory calculations. Both being kinetically and thermodynamically favorable, the reaction barriers are as low as 13.7 and 16.6 kcal/mol, respectively. Additionally, such a σ0π2 carbene can also achieve a series of X-H insertion reactions (X = H, CH3, Bpin, or SiH2Ph), with activation energies ranging from 8.2 to 15.3 kcal/mol. Our findings highlight a strong potential of carbenes with σ0π2 electronic configuration in N2 activation and its versatile transformations, providing valuable insights into main-group-element-mediated N2 activation chemistry.

Promoting activation of N2 and H2O via dual active sites synergistically for efficient photocatalytic ammonia synthesis

Promoting activation of N2 and H2O via dual active sites synergistically for efficient photocatalytic ammonia synthesis

Regulating Multifunctional Oxygen Vacancies for Plasma‐Driven Air‐to‐Ammonia Conversion

Current ammonia (NH3) synthesis is hindered by challenges including N2 activation, NH3 separation, and process complexity. Here we report a plasma‐electrochemical process for the production of gaseous ammonia from air generated NOx, decoupled from processes employing liquid phase intermediaries such as NO3− and final product (NH4+). Importantly, this process uses air for scalable ammonia production under ambient conditions, and directly produces gaseous NH3 which facilitates efficient product separation. For NOx reduction to NH3, we propose a universal strategy combining plasma pretreatment and wet chemical calcination to introduce multifunctional oxygen vacancies. The resulting highly defective Fe2O3 nanoparticles on Cu achieves a significant ammonia production rate of 628 nmol·s−1·cm−2, along with nearly 100% Faradaic efficiency.

Regulating Multifunctional Oxygen Vacancies for Plasma-Driven Air-to-Ammonia Conversion.

Current ammonia (NH3) synthesis is hindered by challenges including N2 activation, NH3 separation, and process complexity. Here we report a plasma-electrochemical process for the production of gaseous ammonia from air generated NOx, decoupled from processes employing liquid phase intermediaries such as NO3- and final product (NH4+). Importantly, this process uses air for scalable ammonia production under ambient conditions, and directly produces gaseous NH3 which facilitates efficient product separation. For NOx reduction to NH3, we propose a universal strategy combining plasma pretreatment and wet chemical calcination to introduce multifunctional oxygen vacancies. The resulting highly defective Fe2O3 nanoparticles on Cu achieves a significant ammonia production rate of 628 nmol·s-1·cm-2, along with nearly 100% Faradaic efficiency.

Doping C60 with single or dual fe atoms for nitrogen reduction reaction: a DFT study

Abstract In this work, we conducted a detailed investigation of the catalytic mechanism of the electrocatalytic nitrogen reduction reaction (NRR) by density functional theory (DFT) calculations, focusing on fullerene (C60) doped with single or dual Fe atoms. The results indicate that single or dual Fe atoms can be stably embedded within defective C60, yielding Fe1C59 and Fe2C58, respectively. Both catalysts exhibit excellent performance in the adsorption and activation of N2, with Fe2C58 demonstrating a certain degree of superiority. Based on the investigation of the NRR reaction pathways on these catalysts, it has been found that, despite varying pathways in different systems, the rate-determining step (RDS) is consistently the first hydrogenation step *N2 → *NNH. Both thermodynamic and kinetic analyses indicate that Fe2C58 exhibits superior catalytic performance compared to Fe1C59. Specifically, the energy barrier for the RDS of the optimal reaction pathway on Fe2C58 is only 0.690 eV. Additionally, Fe2C58 also demonstrates an advantage in suppressing the competitive hydrogen evolution reaction (HER). The present work demonstrates that a catalyst composed of C60 doped with dual Fe atoms exhibits superior stability, electrocatalytic activity, and selectivity for NRR compared to a catalyst doped with a single Fe atom. This research provides a foundation for the design and synthesis of other heteroatom-doped fullerene catalysts.

Cooperative Iron-Aluminium Reactivity for Dinitrogen Activation.

We report a novel bimetallic approach utilizing cooperative Fe-Al reactivity for N2 activation on the Cp*Fe(1,2-Cy2PC6H4AlEt) platform, effectively capturing two N2 molecules through intermolecular Fe-N≡N-Al coordination. Characterizations of the N2-bridged Fe-Al dimer (2) using Mössbauer spectroscopy and density functional theory calculations reveals its electronic structure as a resonance hybrid between Fe(+2)-Al(+1) and Fe(0)-Al(+3). The flexible, covalent Fe-Al bonding facilitates the subsequent alkylation of the Al site with nBuLi, leading to the formation of a dinitrogen-lithiated complex (3) that enables the silylation of the terminal N atom. Our findings highlight the significance of leveraging Fe-Al effects as an electron buffer to achieve facile N2 activation.

MXene Jacketed Amorphous Ga2O3 Nanofibers Modulate the Fiber Surface-Rich Electron for Boosted Electrocatalytic Ammonia Synthesis.

Nitrogen (N2) activation and the hydrogen evolution reaction pose significant limitations on the electrocatalytic nitrogen reduction reaction (NRR) performance. The exclusive electronic structure of the main group elements has the advantage of inhibiting hydrogen generation in electrochemical NRR. However, the poor conductivity and activity remain the obstacles to its application. Herein, we report a combination strategy of cation-induced amorphous Ga2O3 nanofibers and heterostructure engineering, thereby effectively enhancing electrocatalytic performance. The amorphization of Ga2O3 nanofibers generates more oxygen vacancies that enhance the N2 activation and electron transfer ability. Additionally, by constructing heterogeneous structures to drive the charge transfer, we enrich electronics on the surface of a-Ga2O3 nanofibers and increase their catalytic activity. Thus, the a-Ga2O3/MXene nanofibers deliver the NH3 yield of 50.00 μg h-1 mg-1 and FE of 19.13% at -0.35 V. We anticipate that these findings will offer a new reference value for further ammonia synthesis research on Ga2O3 materials.

Significant enhancement of nitrogen photofixation to ammonia and hydrogen storage by a MIL-53 (Fe) based novel plasmonic nanocatalysis at ambient condition

Since hydrogen (H2) plays a vital role in industry, its storage is crucial. Typically, H2 is produced through water-splitting and then stored as ammonia. This process is very time-consuming and costly. Plasmonic metal nanocatalysts, including copper (Cu), silver (Ag), and gold (Au), are promising new ways to stimulate photocatalytic reactions. In this study, Ag/AgCl and Pd plasmonic NPs on the MIL-53 (Fe) by solvothermal method for Nitrogen (N2) photofixation to ammonia (NH3) with high efficiency under ambient conditions. Famous techniques such as FT-IR, XRD, BET, SEM, EDX/Map TEM, and TGA/DSC have been used to determine and confirm physicochemical surface variation while preparing and modifying the MIL-53 (Fe)@Ag/AgCl and MIL-53 (Fe)@Pd0 nanocatalysts. The synthesized plasmonic nanocatalysts display better photocatalytic activities during N2 photofixation, with a maximum NH3 production rate of 183.547 µmol·h− 1·g− 1 (MIL-53 (Fe)@Ag/AgCl(20%)) and 106.746 µmol·h− 1·g− 1 (MIL-53 (Fe)@Pd0(2%)) under visible light irradiation. This issue was attributed to the ability of Ag and Pd plasmonic NPs to harvest light to produce abundant hot electrons and Fe NPs to create active sites for N2 adsorption and activation. The MIL-53 (Fe)@Ag/AgCl(20%) and MIL-53 (Fe)@Pd0(2%) plasmonic compared to MIL-53 (Fe), have increased by 20-fold and 12-fold, respectively. This work of MOF-based plasmonic nanocatalysts for the N2 to NH3 photofixation will provide insight into the rational design of catalysts with high efficiency at ambient conditions.

Effective N2 activation strategies for electrochemical ammonia synthesis

Effective N2 activation strategies for electrochemical ammonia synthesis

Size Effect of Surface Defects Dictates Reactivity for Nitrogen Electrofixation

AbstractElectrocatalytic nitrogen reduction reaction (eNRR) offers a sustainable pathway for ammonia (NH3) production. Defect engineering enhances eNRR activity but can concurrently amplify the competing hydrogen evolution reaction (HER), posing challenges for achieving high selectivity. Herein, VOx with systematically tuned defect sizes is engineered to establish a structure–activity relationship between defect size and eNRR performance. In situ spectroscopy and theoretical calculations reveal that medium‐sized defects (VOx‐MD, 1–2 nm) provide an optimal electronic environment for enhanced N2 adsorption and activation while maintaining spatial flexibility to facilitate efficient hydrogenation. Consequently, VOx‐MD exhibits outstanding eNRR performance, achieving an NH3 yield rate of 81.94 ± 1.45 µg h−1 mg−1 and a Faradaic efficiency of 31.97 ± 0.75 % at −0.5 V (vs RHE). These findings highlight the critical role of defect size in governing eNRR activity, offering a scalable strategy for designing advanced catalysts for competitve electrocatalytic reactions.

Lattice Distortion Broadens the eg Band of Co3O4 to Facilitate p-d Hybridization for Enhanced Electrochemical Nitrate Synthesis.

The electrochemical nitrogen oxidation reaction (NOR) presents a sustainable pathway for nitrate synthesis under mild conditions; however, the process is hindered by the inadequate adsorption and activation of N2 on electrocatalysts. In this study, we utilized Co3O4 as a model catalyst and engineered lattice distortions by introducing oxygen vacancies, which expanded the eg band of the active sites to enhance N2 activation. The modified Co3O4 catalyst achieved a Faradaic efficiency of 10.68% and a nitrate yield of 58.80 μg·h-1·mgcat-1. Comprehensive experimental and density functional theory (DFT) analyses demonstrated that these modifications resulted in a shortened Co-N bond length and an elongated N≡N bond, leading to improved p-d hybridization between N2 and Co sites. Moreover, the enhancements in catalytic performance were also attributed to the improved electron transfer properties stemming from the altered band structure of Co3O4. This work provides innovative design principles for catalysts aimed at facilitating complex electrocatalytic reactions with multiple kinetics.

Regulating the spin state of a single Fe atom in BiOBr to enhance photocatalytic nitrogen reduction: insights from theoretical studies.

Herein, we investigated the effects of the spin state of a single Fe atom on the nitrogen reduction reaction (NRR) in BiOBr using density functional theory. Our simulations revealed that P doping can reduce the spin state of the single Fe atom. This leads to an overlap of orbitals between N2 and the Fe atom at the Fermi energy level, thereby promoting the activation of N2. The investigation of NRR mechanisms revealed that the enzymatic mechanism is more favorable compared to the distal and alternating mechanisms. The formation of NNH with an energy barrier of 2.32 eV is identified as the rate-determining step for the NRR process in the Fe-doped BiOBr system. Furthermore, P doping dramatically reduces the energy barrier of the rate-determining step, which involves releasing the second NH3 molecule, by a factor of 2.37. This study elucidates the influence mechanism of the Fe spin state on the performance of the NRR, providing valuable theoretical guidance for designing highly efficient photocatalysts.

Boosted Scavenger-Free Overall Nitrogen Photofixation with Molybdenum Incorporated Bismuth-Rich Oxychlorides.

The design of highly efficient photocatalysts to photoreduce nitrogen (N2) to ammonia (NH3) under mild conditions is extremely challenging. In this work, various molar ratio of molybdenum (Mo) is incorporated into Bi12O17Cl2 via a hydrothermal process. The resulting Mo-doped Bi12O17Cl2 exhibits remarkable solar-driven activity for N2 photo fixation without any scavengers or sacrificial agents. The optimal sample with 5% Mo dopants displays an NH3 yield of 39.83µmolg-1h-1, a 1.6-fold improvement over undoped pristine Bi12O17Cl2. The impressive performance is attributed to the synergistic effects of oxygen vacancies (OVs) and Mo-loading, enhancing light absorption and extending photo-response through band gap reduction. Additional contributions arise from the enriched active sites, facilitating N2 adsorption and electron transport to the reactants. Density functional theory calculations reveal that Mo integration induces significant charge redistribution around the active sites, thereby reducing the energy barrier associated with N2 activation and protonation. In-depth investigation into the reaction pathway unravels the step-by-step reaction process which further elucidates the beneficial role of Mo loading in the overall N2 photoconversion process. As a whole, this work promotes a simple and effective engineering approach based on heteroatom doping as an efficacious strategy to design highly active photocatalysts toward N2 photo fixation.

Enabling Unconventional “Alternating‐Distal” N2 Reduction Pathway for Efficient Ammonia Electrosynthesis

AbstractThe general understanding on the reaction path is that the electrocatalytic N2 reduction follows either individual associative alternating or distal pathways, where efficient N2 activation and selective NH3 production are very challenging. Herein, an unconventional “alternating‐distal” pathway was achieved by shifting the “*NHNH2→*NH2NH2” to “*NHNH2→*NH + NH3” step to boost NH3 synthesis with an amorphous CeMnOx electrocatalyst. In this unconventional process, N2 activation was realized through π back donation on the Mn site, while the Mn/Ce dual active sites could regulate the intermediate configurations to avoid the nitrogen‐containing by‐product formation. Such “alternating‐distal” pathway was affirmed by in situ spectroscopic analyses and theoretical calculations. In a neutral media, an average ammonia production rate of 82.8 µg h−1 mg−1 and an outstanding Faradaic efficiency of 37.3% were attained. This work validated an unconventional mechanism in electrocatalytic ammonia synthesis, which might be extended to other catalytic process with multiple possible reaction paths.

Synergistic Enhancement of Capacitive Performance in Porous Carbon by Phenolic Resin and Boric Acid.

The study of pore structure regulation methods has always been a central focus in enhancing the capacitance performance of porous carbon electrodes in lithium-ion capacitors (LICs). This study proposes a novel approach for the synergistic regulation of the pore structure in porous carbon using phenol-formaldehyde (PF) resin and boric acid (BA). PF and BA are initially dissolved and adsorbed onto porous carbon, followed by hydrothermal treatment and subsequent heat treatment in a N2 atmosphere to obtain the porous carbon materials. The results reveal that adding BA alone has almost no influence on the pore structure, whereas adding PF alone significantly increases the micropores. Furthermore, the simultaneous addition of PF and BA demonstrates a clear synergistic effect. The CO2 and H2O released during the PF pyrolysis contribute to the development of ultramicropores. At the same time, BA facilitates the N2 activation reaction of carbon, enlarging the small mesopores and aiding their transformation into bottlenecked structures. The resulting porous carbon demonstrates an impressive capacitance of 144 F·g-1 at 1 A·g-1 and a capacity retention of 19.44% at 20 A·g-1. This mechanism of B-catalyzed N2-enhanced mesopore formation provides a new avenue for preparing porous carbon materials. This type of porous carbon exhibits promising potential for applications in Li-S battery cathode materials and as catalyst supports.

Size Effect of Surface Defects Dictates Reactivity for Nitrogen Electrofixation.

Electrocatalytic nitrogen reduction reaction (eNRR) offers a sustainable pathway for ammonia (NH3) production. Defect engineering enhances eNRR activity but can concurrently amplify the competing hydrogen evolution reaction (HER), posing challenges for achieving high selectivity. Herein, VOx with systematically tuned defect sizes is engineered to establish a structure-activity relationship between defect size and eNRR performance. In situ spectroscopy and theoretical calculations reveal that medium-sized defects (VOx-MD, 1-2 nm) provide an optimal electronic environment for enhanced N2 adsorption and activation while maintaining spatial flexibility to facilitate efficient hydrogenation. Consequently, VOx-MD exhibits outstanding eNRR performance, achieving an NH3 yield rate of 81.94± 1.45µg h-1 mg-1 and a Faradaic efficiency of 31.97± 0.75% at -0.5 V (vs RHE). These findings highlight the critical role of defect size in governing eNRR activity, offering a scalable strategy for designing advanced catalysts for competitve electrocatalytic reactions.

Advancing electrochemical water desalination: Machine learning-driven prediction and RSM optimization of activated carbon electrodes

Advancing electrochemical water desalination: Machine learning-driven prediction and RSM optimization of activated carbon electrodes

Enabling Unconventional "Alternating-Distal" N2 Reduction Pathway for Efficient Ammonia Electrosynthesis.

The general understanding on the reaction path is that the electrocatalyticN2 reduction follows either individual associative alternating or distal pathways, where efficient N2 activation and selective NH3 production are very challenging. Herein, an unconventional "alternating-distal" pathway was achieved by shifting the "*NHNH2→*NH2NH2" to "*NHNH2→*NH+NH3" step to boost NH3 synthesis with an amorphous CeMnOx electrocatalyst. In this unconventional process, N2 activation was realized through π back donation on the Mn site, while the Mn/Ce dual active sites could regulate the intermediate configurations to avoid the nitrogen-containing by-product formation. Such "alternating-distal" pathway was affirmed by in situ spectroscopic analyses and theoretical calculations. In a neutral media, an average ammonia production rate of 82.8µg h-1 mg-1 and an outstanding Faradaic efficiency of 37.3% were attained. This work validated an unconventional mechanism in electrocatalytic ammonia synthesis, which might be extended to other catalytic process with multiple possible reaction paths.

Dual Activation of N2 and CO2 toward N-O Coupling by Single Copper Ions.

Concurrent activation and conversion of N2 and CO2 are of significance yet face numerous obstacles due to the large dissociation energies of N≡N and C═O bonds. Utilizing a specifically developed reflectron time-of-flight mass spectrometer, we investigated the dual activation of N2 and CO2 mediated by copper and silver ions under ambient conditions. Isotope experiments identified that both N2 and CO2 can be effectively activated to generate a N-O coupling product (NO+), especially in the presence of copper ions, and the NO+ product attains the maximum intensity with an N2/CO2 ratio of 1:2, which validates a three-molecule reaction mechanism, namely, N2 + 2CO2 → 2NO + 2CO. Through detailed analyses of thermo-dynamics and reaction dynamics, we illustrate the Cu+-catalyzed three-molecule reaction mechanism for N-O coupling, validating the dual activation of N2 and CO2 simply by plasma-assisted single-ion catalysis.