The nitrogen reduction reaction (NRR), as an efficient and green pathway for ammonia synthesis, plays a crucial role in achieving on-demand ammonia production. This study proposes a novel design concept based on dual-iron atomic sites and nitrogen-boron co-doped graphene catalysts, exploring their high efficiency in NRR. By modulating the N and B co-doped ratios, we found that Fe2N3B@G catalyst exhibited significant activity in the adsorption and hydrogenation of N2 molecules, especially with the lowest free energy (0.32 eV) on NRR distal pathway, showing its excellent nitrogen activation capability and NRR performance. The computed electron localization function, crystal orbital Hamiltonian population, electrostatic potential map revealed that the improved NRR kinetics of Fe2N3B@G catalyst derived by N3B co-doping induced optimization of Fe-Fe electronic environment, regulation of Fe-N bond strength, and the continuous electronic support during the N2 breakage and hydrogenation. In particular, machine learning molecular dynamics (MLMD) simulations were employed to verify the high activity of Fe2N3B@G catalyst in NRR, which reveal that Fe2N3B@G effectively regulates the electron density of Fe-N bond, ensuring the smooth generation and desorption of NH3 molecules and avoiding the competition with hydrogen evolution reaction (HER). Furthermore, the determined higher HER overpotential of Fe2N3B@G catalyst can effectively inhibit the HER and enhance the selectivity toward NRR. In addition, Fe2N3B@G catalyst also showed good thermal stability by MD simulations up to 500 K, offering its feasibility in practical applications. This study demonstrates the superior performance of Fe2N3B@G in nitrogen reduction catalysis, and provides theoretical guidance for atomic catalyst design by the co-doping strategy and in-deep electronic environment modulation.
Nitrogen-containing Surface Ligands Lead to False Positives for Photofixation of N$_2$ on Metal Oxide Nanocrystals: An Experimental and Theoretical Study
The discovery of metals as catalytic centers for nitrogen reduction reactions has stimulated great enthusiasm for single-atom catalysts. However, the poor activity and low selectivity of available SACs are far away from the industrial requirement. Through the high throughout first principles calculations, the doping engineering can effectively regulate the NRR performance of b-Sb monolayer. Especially, the origin of activated N2 is revealed from the perspective of the electronic structure of the active center. Among the 24 transition metal dopants, Re@Sb and Tc@Sb showed the best NRR catalytic…
A new steady-state kinetic model of ammonia decomposition is presented and analyzed regarding the electronic properties of metal catalysts. The model is based on the classical Temkin-Ertl mechanism and modified in accordance with Wolkenstein electronic theory by implementing participation of free electrons of the catalyst to change the chemical nature of adsorbed species. Wolkenstein original theory only applied to semiconductors but by including the d-band model, the electronic theory can be extended to metals. For both simplified and full reaction mechanisms, including electronic steps, we p…
Converting earth-abundant dinitrogen into value-added chemical ammonia is a significant yet challenging topic. Electrocatalytic nitrogen reduction reaction (NRR), compared with conventional Haber-Bosch process, is an energy-saving and environmentally friendly approach. The major task of electrocatalytic NRR is to find electrocatalysts which can activate dinitrogen effectively and exhibit high selectivity and stability. Single atom catalysts can act as a good solution. In this work, by means of first-principles density functional theory, molecular dynamics calculations, and a two-step screening…
Using a dual plasma process to produce cobalt--polypyrrole catalysts for the oxygen reduction reaction in fuel cells -- part II: analysing the chemical structure of the films
Ammonia (NH3) is mainly produced through the traditional Haber-Bosch process under harsh conditions with huge energy consumption and massive carbon dioxide (CO2) emission. The nitrogen electroreduction reaction (NERR), as an energy-efficient and environment-friendly process of converting nitrogen (N2) to NH3 under ambient conditions, has been regarded as a promising alternative to the Haber-Bosch process and has received enormous interest in recent years. Although some exciting progress has been made, considerable scientific and technical challenges still exist in improving the NH3 yield rate …
Warsaw University of Technology（华沙理工大学）；Lublin University of Technology（卢布林理工大学）；BCMaterials, Basque Center for Materials, Applications and Nanostructures, UPV/EHU Science Park（BCMaterials，巴斯克材料、应用和纳米结构中心，UPV/EHU科学园）；Ikerbasque, Basque Foundation for Science（Ikerbasque，巴斯克科学基金会）；Cranfield University（克兰菲尔德大学）
Photocatalytic nitrogen fixation from air directly under sunlight can contribute significantly to carbon neutralization. It is an ideal pathway to replace the industrial Haber Bosch process in future. A Fe-doped layered WO$_3$ photocatalyst containing oxygen vacancies was developed which can fix nitrogen from air directly under sunlight at atmospheric pressure. The iron doping enhances the transport efficiency of photogenerated electrons. The photocatalytic efficiency is around 4 times higher than that of pure WO$_3$. The optimum nitrogen fixation conditions were examined by orthogonal experim…
Nitrogen doping of the carbon is an important method to improve the performance and durability of catalysts for proton exchange membrane fuel cells by platinum-nitrogen and carbon-nitrogen bonds. This study shows that p-phenyl groups and graphitic N acting bridges linking platinum and the graphene/carbon black (the ratio graphene/carbon black=2/3) hybrid support materials achieved the average size of platinum nanoparticles with (4.88 +/- 1.79) nm. It improved the performance of the lower-temperature hydrogen fuel cell up to 0.934 W cm-2 at 0.60 V, which is 1.55 times greater than that of comme…
Hexagonal boron nitride (h-BN) is well-established as a requisite support, encapsulant and barrier for 2D material technologies, but also recently as an active material for applications ranging from hyperbolic metasurfaces to room temperature single-photon sources. Cost-effective, scalable and high quality growth techniques for h-BN layers are critically required. We utilise widely-available iron foils for the catalytic chemical vapour deposition (CVD) of h BN and report on the significant role of bulk dissolved species in h-BN CVD, and specifically, the balance between dissolved oxygen and ca…
Nitrogen reduction reaction (NRR) which converts nitrogen (N2) to ammonia (NH3) normally requires harsh conditions to break the bound nitrogen bond. Herein, via first-principles calculation we reveal that a superior NRR catalytic activity could be obtained through anchoring atomic catalyst above a phosphorene-like puckering surface of germanium selenide (GeSe). Through examining the single- and double- atoms (B, Fe, W, Mo and Ru) decorated on GeSe, we find that its rippled structure allows an intimate contact between the deposited species and the GeSe which significantly promotes the states hy…
An Atomic-Scale View of CO and H2 Oxidation on a Pt-Fe3O4 Model Catalyst
金属-载体相互作用经常被用来解释分散在可还原的金属氧化物载体上的金属纳米颗粒的增强的催化活性，但原子尺度的机制很少有人知道。在这里，我们使用扫描隧道显微镜研究Pt 1 -6/Fe 3 O 4模型催化剂暴露于CO，H2，O2，及其混合物，在550 K。CO在簇周边提取晶格氧以形成CO2，在金属氧化物表面产生大孔。H2和O2在金属簇上解离并溢出到载体上。前者产生表面羟基，其与载体反应以解吸水，而原子氧与本体中的Fe反应以产生新的Fe 3 O 4（001）岛。铂的存在是至关重要的，因为它催化已经发生在裸露的氧化铁表面上的反应，但在更高的温度下。
Co3O4 Nanocrystals on Graphene as a Synergistic Catalyst for Oxygen Reduction Reaction
用于氧还原和析氧反应的催化剂是包括燃料电池和水分解在内的关键可再生能源技术的核心。尽管付出了巨大的努力，但开发低成本高活性的氧电极催化剂仍然是一个巨大的挑战。在这里，我们报告了一种在还原氧化石墨烯（GO）上生长的Co 3 O 4纳米晶体的混合材料，作为用于氧还原反应（ORR）和析氧反应（OER）的高性能双功能催化剂。虽然单独的Co 3 O 4或氧化石墨烯几乎没有催化活性，但它们的混合物表现出意想不到的、令人惊讶的高ORR活性，其通过石墨烯的氮掺杂进一步增强。Co 3 O 4/N掺杂的石墨烯混合物在碱性溶液中表现出与Pt相似的催化活性，但具有优异的稳定性。该混合物对OER也具有高活性，使其成为ORR和OER的高性能非贵金属基双催化剂。不寻常的催化活性来自Co 3 O 4和石墨烯之间的协同化学耦合效应。
Electrocatalysts for the oxygen reduction reaction (ORR) based on complexes of iron and nitrogen in a carbon matrix (Fe-N-C) are a promising alternative to platinum group metal (PGM) based catalysts in polymer electrolyte membrane (PEM) fuel cells. Further improvements of Fe-N-C catalysts would benefit from model thin film studies of activity and stability of catalytic sites, but synthesis of Fe-N-C model thin films is challenging. Here we report on synthesis and characterization of Fe-N-C thin films produced by co-sputtering iron and carbon in a reactive nitrogen atmosphere onto removable gla…
The Key Steps and Distinct Performance Trends of Pyrrolic vs. Pyridinic M-N-C Catalysts in Electrocatalytic Nitrate Reduction
Advanced Institute for Materials Research (WPI-AIMR), Tohoku University（东北大学物质材料研究创新世界首脑研究所）；School of Chemical and Biomolecular Engineering, The University of Sydney（悉尼大学化学与生物分子工程学院）；State Key Laboratory of Rare Earth Resource Utilization, Changchun Institute of Applied Chemistry, Chinese Academy of Sciences（中国科学院长春应用化学研究所稀土资源利用国家重点实验室）；School of Applied Chemistry and Engineering, University of Science and Technology of China（中国科学技术大学应用化学与工程学院）
Using a dual plasma process to produce cobalt--polypyrrole catalysts for the oxygen reduction reaction in fuel cells -- part I: characterisation of the catalytic activity and surface structure
介绍了一种新的双等离子体涂层工艺，用于制备燃料电池中氧还原反应的无铂催化剂。用各种方法分析由此产生的催化剂。通过循环伏安法、旋转环电极和旋转环盘电极进行电化学表征。由此获得的不同的催化剂的表面孔隙率的特征在于与氮气吸附技术和扫描电子显微镜用于确定膜的生长机制。它表明，催化活性化合物可以用这种双等离子体工艺生产。此外，催化活性可以通过改变等离子体工艺参数而显著变化。计算了生成的H $_2$ O $_2$的量，并表明2电子机理是主要的。等离子体涂覆机制不会显著改变所用碳载体的表面BET面积和孔径分布。此外，所产生的薄膜的扫描电子显微镜照片，并示出的柱状生长机制的偏好。通过使用不同的碳作为载体，它表明，有很强的依赖性的催化活性，这可能是有关的碳的化学性质。
Photoelectrocatalytic (PEC) reduction of N2 to ammonia (NH3) is emerging as the potential alternative to overcome the standard Haber-Bosch approach. In this communication, solar N2 reduction was demonstrated with molybdenum carbide (Mo2C) co-catalyst assisted indium gallium nitride (InGaN) nanowires. The effect of aiding Mo2C on InGaN NWs arrests the dark current and demonstrated the saturation current under illumination was briefly elucidated. Large NH3 production of 7.2 gh-1cm-2 with high Faradaic efficiency of 12.6 % was realized at -0.2 V vs. reversible hydrogen electrode for the Mo2C/GaN/…
Metal heteroatoms dispersed in nitrogen-doped graphene display promising catalytic activity for fuel cell reactions such as the hydrogen evolution reaction (HER). Here we explore the effects of dopant concentration on the synergistic catalytic behaviour of a paired metal atom active site comprised of Co and Pt atoms. The metals are coordinated to six atoms in a vacancy of N-doped graphene. We find that HER activity is enhanced with increasing N concentration, where the free energy of hydrogen atom adsorption ranges from 0.23 to -0.42 eV as the doping changes from a single N atom doped in the p…
Structures of iron and cobalt bimetallic clusters for optimized chemical vapor deposition growth of single-walled carbon nanotubes
The University of Tokyo（东京大学）；Center for Multidimensional Carbon Materials (CMCM), Institute for Basic Science (IBS)（基础科学研究院多维碳材料中心）；Dalian University of Technology（大连理工大学）；University of Antwerp（安特卫普大学）
The successful synthesis of high entropy alloy (HEA) nanoparticles, a long-sought goal in materials science, opens a new frontier in materials science with applications across catalysis, electronics, structural alloys, and energetic materials. Recently, a Co25Mo45Fe10Ni10Cu10 HEA made of earth-abundant elements was shown to have a high catalytic activity for ammonia decomposition, which rivals that of state-of-the-art, but prohibitively expensive, ruthenium catalyst. Using a computational approach based on first-principles calculations in conjunction with data analytics and machine learning, w…
It has been well established that nitrogen coordinated transition metal, TM-N$_{4}$-C (TM$=$Fe and Co) moieties, are responsible for the higher catalytic activity for the electrochemical oxygen reduction reaction. However, the results obtained using density functional theory calculations vary from one to another, which can lead to controversy. Herein, we assess the accuracy of the theoretical approach using different class of exchange-correlation functionals, i.e., Perdew-Burke-Ernzerhof (PBE) and revised PBE (RPBE), those with the Grimme's semiempirical dispersion correction (PBE+D3 and RPBE+…
Nickel-iron layered double hydroxide (NiFe LDH) platelets with high morphological regularity and sub-micrometre lateral dimensions were synthesized using a homogeneous precipitation technique for highly efficient catalysis of the oxygen evolution reaction (OER). Considering edge sites are the point of activity, efforts were made to control platelet size within the synthesized dispersions. The goal is to controllably isolate and characterize size-reduced NiFe LDH particles. Synthetic approaches for size control of NiFe LDH platelets have not been transferable based on published work with other …
A catalyst surface may be exposed to strain due to application of load or interfacing with a substrate with large lattice mismatch. In order to test the effect of strain on catalytic efficiency, we use Density Functional Theory +U (DFT+U) to model water oxidation on expanded and contracted surfaces of the Ni1-xFexOOH alloy, one of the best known catalysts for water splitting. We find that a low amount of iron content has a similar effect as of applying compressive strain. Due to high oxidation state of Fe4+ at the active site, the Fe-O bond is shorter than in pure FeOOH, which is beneficial fo…
The hybrid nanostructures of nitrogen doped carbon materials and nonprecious transition metals are among the most promising electrocatalysts to replace noble metal catalysts for renewable energy applications. However, the fundamental principles governing the catalytic activity of such hybrid materials remain elusive. Herein, we systematically explore the electrocatalytic properties of transition metals, transition metal oxides and carbides substrates covered by nitrogen-doped graphitic sheets for hydrogen evolution reaction (HER). Our first-principles calculations show that the graphitic sheet…
Electrocatalysts of nitrogen reduction reaction (NRR) have attracted ever-growing attention due to its application for renewable energy alternative to fossil fuels. However, activation of inert N-N bond requires multiple complex charge injection which complicates the design of the catalysts. Here via combining atomic-scale screening and machine learning (ML) methods we explore the rational design of NRR single-atom catalysts (SACs) supported by molybdenum disulfide (MoS2). Our work reveals that the activity of NRR SACs is highly dependent on the number of unpaired d electrons of TM: positive s…
Structural, electronic, and magnetic properties of tris(8-hydroxyquinoline)iron(III) molecules and its magnetic coupling with ferromagnetic surface: first-principles study
Low-energy spectrum of iron-sulfur clusters directly from many-particle quantum mechanics
FeS簇是一种普遍的生物基序。它们在固氮、呼吸和光合作用等不同过程中进行电子转移、氧化还原化学甚至氧传感。低电子态是其显着反应性的关键，但不能直接观察到。本文首次对[2Fe-2S]和[4Fe-4S]团簇的电子能级进行了量子计算。我们的研究结果突出了其电子结构的长期模型的局限性。特别是，我们证明了广泛使用的海森堡双交换模型低估了1-2个数量级的状态，这可以最终追溯到没有Fe d $\rightarrow$ d激发，被认为是重要的，在这些集群的数量。此外，即使是相同自旋的电子能级在振动波动的尺度上也是密集的，这为这些簇在自然界中催化反应的普遍性提供了自然的解释。
Experimentally discovered compounds in the iron-nitrogen system belong to the low concentration part of the Fe-N phase diagram. In our paper, which is based on ab initio calculations we have studied formation and stability of high-pressure iron mono-nitride phases, and particularly the new magnetic phase with a NiAs-type structure. We have investigated the role of dynamic, thermodynamic and electronic properties, such as electronic correlations and pressure-induced phase stabilisation. We demonstrate that the new hexagonal FeN phase is stable for a wide range of external pressure and it can be…
