Artificial Nitrogen Fixation Research Articles

Carbon dioxide mixed air promoting plasma-driven nitrogen oxidation conversion

Utilization of plasma-driven direct nitrogen oxidation for the production of nitrates presents a promising strategy for realizing artificial nitrogen fixation while minimizing carbon emissions. However, the conventional plasma-driven synthesis method employing air as the feed gas exhibits unsatisfactory nitrogen conversion efficiency due to insufficient oxygen. In this study, we introduced carbon dioxide as an additional source of oxygen and mixed it with air, utilizing electrochemically synthesized copper nanoparticles as a catalyst, which significantly improved the efficiency of plasma-driven nitrogen oxidation. The introduction of carbon dioxide not only provides sufficient O* for the nitrogen oxidation process, but also facilitates the high-value conversion of carbon dioxide with 99.99% selectivity in the synthesis of carbon monoxide. Additionally, we also designed a cyclic reaction device to further enhance the nitrogen oxidation efficiency. As a result, this plasma-driven cycle reaction system achieved a maximum nitrogen conversion rate of up to 11.4%.

Accelerating electron transfer dynamics for efficient nitrogen photoreduction on nitrogenase-mimicking metal-organic framework/Fe-dispersed MXene

Achieving efficient artificial nitrogen fixation similar to nitrogenase under mild conditions has always been a goal pursued by human beings, but it remains a huge challenge. Herein, a novel photothermal catalyst UiO-66(Zr-Fe)/Fe-dispersed MXene having nitrogenase-mimicking electron transfer structure and electron donation mechanism is fabricated and applied in a designed gas-vapor-solid bi-phase system for efficient N2-to-NH3 conversion. The complementary role playing of UiO-66(Zr-Fe), Ti3C2 MXene and well-dispersed Fe sites are capable of simulating nitrogenase triple tandem system that in charge of electron generation, electron transfer and N2 fixation, respectively. In this well-designed catalyst, a remarkably high NH3 formation rate of 133.2 μmol g−1 h−1 under solar level illumination is recorded. This superior performance of the biomimetic structure is related to the enhanced light-to-matter interaction for effective multi-electron extraction and promoted photothermal response for accelerating surface reaction dynamics.

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.

Computational design of two-dimensional transition metal supported biphenylene as efficient electrocatalysts toward nitrogen reduction reaction

Electrochemical nitrogen reduction reaction (eNRR) at standard conditions shows promise as an innovative approach for artificial nitrogen fixation, potentially offering a more energy-efficient alternative to the Haber-Bosch method. Design and evolution of low-cost and high-efficiency electrocatalysts remain the significant challenge confronting eNRR. Single-atom catalysts have recently been intensively explored due to their 100% utilization, high activity, and high selectivity. Here, a series of transition metal atom anchored on biphenylene (TM−BPN, TM = Sc−Hg) are studied as electrocatalysts (SACs) for eNRR by density functional theory computation. Among them, 19 SACs are screened out as the most promising electrocatalyst with lower limiting potential than that on the stepped Ru (0001). The Re−BPN catalyst exhibits the highest catalytic activity with a lowest limiting potential of -0.48 V. In addition, the Re−BPN also exhibits high eNRR selectivity by suppressing the competing hydrogen evolution reaction with the Faradaic efficiency being ∼100%. Partial density of states and Bader charge analysis illuminate the origin of eNRR catalytic activity of TM−BPN. Furthermore, the SAC structure remains intact under 500 K with no bond breaking. This study deepens our insight into the utilization of SACs in N2 fixation, contributing significantly to the exploration of efficient electrocatalysts for eNRR.

Tailored Metal-Porphyrin Based Molecular Electrocatalysts for Enhanced Artificial Nitrogen Fixation to Green Ammonia.

Electrochemical nitrogen reduction (E-NRR) is one of the most promising approaches to generate green NH3. However, scarce ammonia yields and Faradaic efficiencies (FE) still limit their use on a large scale. Thus, efforts are focusing on different E-NRR catalyst structures and formulations. Among present strategies, molecular electrocatalysts such as metal-porphyrins emerge as an encouraging option due to their planar structures which favor the interaction involving the metal center, responsible for adsorption and activation of nitrogen. Nevertheless, the high hydrophobicity of porphyrins limits the aqueous electrolyte-catalyst interaction lowering yields. This work introduces a new class of metal-porphyrin based catalysts, bearing hydrophilic tris(ethyleneglycol) monomethyl ether chains (metal = Cu(II) and CoII)). Experimental results show that the presence of hydrophilic chains significantly increases ammonia yields and FE, supporting the relevance of fruitful catalyst-electrolyte interactions. This study also investigates the use of hydrophobic branched alkyl chains for comparison, resulting in similar performances with respect to the unsubstituted metal-porphyrin, taken as a reference, further confirming that the appropriate design of electrocatalysts carrying peripheral hydrophilic substituents is able to improve device performances in the generation of green ammonia.

Enhanced electrochemical reduction of N2 to NH3 by interfacial engineering of biomass-derived Fe, Mo-bimetallic composite

Electrocatalytic nitrogen reduction reaction (NRR) for the synthesis of ammonia (NH3) is one of the green and mild methods of artificial nitrogen fixation, promising as an alternative to replace the existing industrial process. Under the requirements of green chemistry and sustainable development, the design and development of highly active and stable electrocatalysts is very important for improved synthesis performance. Mimicking from the natural nitrogenase, Fe and Mo based catalysts have attracted much attention due to their superior catalytic performance for N2 adsorption and activation. In this work, an interfacial engineering strategy has been used to prepare a Fe, Mo-bimetallic electrocatalyst for the electrosynthesis of NH3. In detail, the pre-pyrolyzed biochar-based Fe2O3 composites were decorated with nano-flowered MoS2/MoO2 hybrids by a solvothermal process (MoS2/MoO2@Fe2O3/BC). As confirmed by the extensive characterization, the further modification not only introduced functional counterparts into the electrocatalysts but also regulated the morphology of the nanostructure. The electrochemical tests showed that the highest NH3 yield rate of MoS2/MoO2@Fe2O3/BC was 4.87 μg h− 1 cm−2 and highest FE was 16.5% in 0.1 M Na2SO4. The catalytic stability and durability were also presented in the longtime electrolysis and cycling experiments. The improved catalytic performance of decorated catalyst, as evidenced by the comparison with Fe2O3/BC, is attributed to the increased electrocatalytic active area, the moderated hydrophilicity, and the synergistic effect of Fe, Mo-bimetallic active sites. This study provides a new perspective for the design and development of low-cost transition metal complexes as electrocatalysts for nitrogen reduction reactions.

Electrocatalytic nitrogen cycle: mechanism, materials, and momentum

Artificial nitrogen fixation has been pivotal in escalating agricultural productivity and sustaining exponential human population growth. Nonetheless, these practices have concurrently perturbed the natural nitrogen cycle, engendering a plethora of...

Managing the Scaling Relationship for Plasma-Activated Electrolysis Toward Nitrogen Fixation

To substitute fossil feedstock, storing renewable electricity in chemical bonds has become one of the tremendous and attractive approaches. This approach enables the transformation of base molecules (i.e., H2O, N2, CO2) into energy or chemical-rich molecules. The energy stored in the nitrogen-based compound is a critical biogeochemical cycle in nature due to its essential nutrient for living organisms in the forms of ammonia, nitrates, urea, amino acids, and DNA/RNA nucleotides as well as the high atmospheric volume of 78%. Artificial nitrogen fixation via a catalytic approach powered by sustainable renewables (e.g. wind, solar) provides an alternative as well as promising route to resource the value-added chemicals.N2 is a nonreactive base molecule due to its non-polarity and a strong triple bond between the atoms. Subsequently, even with an active catalyst, a substantial amount of energy is needed to activate N2 [1]. This Account covers our group’s recent advances in solid oxide electrolysis cells (SOECs) for providing reacting species on catalysts in a controllable manner while a radio frequency (RF) plasma is used to increase the reactivity of nitrogen [2,3]. Using oxygen ion or proton conducting SOECs we can produce either ammonia or nitric oxide (via reacting with plasma-activated N2) by suppressing oxygen or hydrogen evolution, respectively. The spatial separation of nitrogen dissociation and catalytic formation of the target molecules provides true independent parameters to optimize the electrocatalytic reactions. In both cases, the concentration of products is orders of magnitude higher than equilibrium (in the absence of plasma) while very high selectivity to nitrogen fixation is observed.To date most of the studies have focused on the material axis, however, recent theoretical studies have revealed that large-scale N2 fixation necessitates the rational design of the reactor, catalyst selectivity, reaction kinetics, and fluid dynamics and thus it keeps the processes far from the optimum performance. In this contribution, we investigate several aspects including flow dynamics, nature of the catalyst, activation energy of the catalytic process, catalyst surface-to-volume ratio, catalyst selectivity, and residence time of plasma-activated nitrogen to reach the catalyst surface, toward solving the aforementioned limitations.

Photosynthetic System Based on a Polyoxometalate-Based Dehydrated Metal-Organic Framework for Nitrogen Fixation.

In nature, biological nitrogen fixation is accomplished through the π-back-bonding mechanism of nitrogenase, which poses significant challenges for mimic artificial systems, thanks to the activation barrier associated with the N≡N bond. Consequently, this motivates us to develop efficient and reusable photocatalysts for artificial nitrogen fixation under mild conditions. We employ a charge-assisted self-assembly process toward encapsulating one polyoxometalate (POM) within a dehydrated Zr-based metal-organic framework (d-UiO-66) exhibiting nitrogen photofixation activities, thereby constructing an enzyme-mimicking photocatalyst. The dehydration of d-UiO-66 is favorable for facilitating nitrogen chemisorption and activation via the unpaired d-orbital electron at the [Zr6O6] cluster. The incorporation of POM guests enhanced the charge separation in the composites, thereby facilitating the transfer of photoexcited electrons into the π* antibonding orbital of chemisorbed N2 for efficient nitrogen fixation. Simultaneously, the catalytic efficiency of SiW9Fe3@d-UiO-66 is enhanced by 9.0 times compared to that of d-UiO-66. Moreover, SiW9Fe3@d-UiO-66 exhibits an apparent quantum efficiency (AQE) of 0.254% at 550 nm. The tactics of "working-in-tandem" achieved by POMs and d-UiO-66 are extremely vital for enhancing artificial ammonia synthesis. This study presents a paradigm for the development of an efficient artificial catalyst for nitrogen photofixation, aiming to mimic the process of biological nitrogen fixation.

Research Progress in Composite Materials for Photocatalytic Nitrogen Fixation.

Ammonia is an essential component of modern chemical products and the building unit of natural life molecules. The Haber-Bosch (H-B) process is mainly used in the ammonia synthesis process in the industry. In this process, nitrogen and hydrogen react to produce ammonia with metal catalysts under high temperatures and pressure. However, the H-B process consumes a lot of energy and simultaneously emits greenhouse gases. In the "double carbon" effect, to promote the combination of photocatalytic technology and artificial nitrogen fixation, the development of green synthetic reactions has been widely discussed. Using an inexhaustible supply of sunlight as a power source, researchers have used photocatalysts to reduce nitrogen to ammonia, which is energy-dense and easy to store and transport. This process completes the conversion from light energy to chemical energy. At the same time, it achieves zero carbon emissions, reducing energy consumption and environmental pollution in industrial ammonia synthesis from the source. The application of photocatalytic technology in the nitrogen cycle has become one of the research hotspots in the new energy field. This article provides a classification of and an introduction to nitrogen-fixing photocatalysts reported in recent years and prospects the future development trends in this field.

Synthesis of spinel type 2D Co3O4 nanodiscs using gallic acid for electrochemical NH3 formation by N2 reduction

The production of ammonia through electrochemical nitrogen reduction reaction (ENRR) has garnered significant interest as a potential method of artificial nitrogen fixation in ambient conditions. This study reports an environmentally friendly synthesis of pristine Co3O4 nanodiscs (NDs) as a catalyst to effectuate electrochemical nitrogen reduction to ammonia. The absorption spectra of Co3O4 NDs revealed two peaks at 435 and 735 nm, indicative of O2− to Co2+/Co3+ charge transfer. The particles exhibited a distinct propensity for the growth along the (311) direction with induced oxygen vacancies which resulted from the release of NOx from the decomposition of precursor in the calcination step. The diameter and thickness of Co3O4 NDs were determined to be 240 and 35.5 nm, respectively. Faradaic efficiency of NH3 production of 2.6% was achieved with a yield rate of 8.8 µg h−1 mgcat.−1 at −1.25 V (vs. Ag/AgCl). Co3O4 NDs/TCP electrode showed six times higher Faradaic efficiency (FE) for ENRR compared to the bare TCP electrode. However, prolong electrolysis could result a reduction in FE due to sacrifice of active Co(III) sites due to the formation of Co(OH)2. Co2+ in tetrahedral sites easily bond with the N≡N, whereas Co3+ in octahedral sites facilitate the electron transfer for ENRR.

Enhanced artificial nitrogen fixation efficiency induced by construction of ternary TiO2/MIL-88A(Fe)/g-C3N4 Z-scheme heterojunction

Herein, a ternary TiO2/MIL-88A(Fe)/g-C3N4 heterojunction is successfully constructed through a facile hydrothermal strategy for enhancing solar energy harvesting and efficiency of catalytic nitrogen reduction induced by enlarged light absorption range, increasing interfacial charge transfer ability and desirable stability. Under the simulated sunlight irradiation, the N2 fixation experiment shows that the yield of NH3 reaches 1084.31 μmol/(g·h) over the TiO2/MIL-88A(Fe)/g-C3N4 photocatalyst, and the yield is significantly enhanced, which is 33.68 and 13.94 times that is higher than the pure TiO2 and g-C3N4, respectively. In a mean time, the excellent performance of the photocatalytic N2 fixation over the ternary TiO2/MIL-88A(Fe)/g-C3N4 is verified based on density function theory calculation and the decisive step over the composite is investigated by calculating Gibbs free energies of nitrogen reduction paths. The performance enhancement mechanism of TiO2/MIL-88A(Fe)/g-C3N4 is speculated, which indicates that the hybridized three-component system presents a desirable Z-scheme band alignment, resulting in the improvement of separation and transfer efficiency of photoinduced charge carriers. The article shows a new and high-efficiency TiO2/MIL-88A(Fe)/g-C3N4 photocatalysis for excellent nitrogen reduction ability.

Enabling circular economy by N-recovery: Electrocatalytic reduction of nitrate with cobalt hydroxide nanocomposites on copper foam treating low conductivity groundwater effluents

Fertilizers play a vital role in the food-energy-water nexus. The traditional method of artificial nitrogen fixation to produce ammonia is a high-energy intensive centralized process that has caused an imbalance of the N-cycle due to the release of N-species to water. Electrocatalytic nitrate reduction (ENR) to ammonia is a promising N-resource recovery alternative that can enable the circular reuse of ammonia in decentralized settings. However, the primary challenge is identifying selective and affordable electrocatalysts. Identifying electrodes that rely on something other than platinum-group metals is required to surpass barriers associated with using expensive and endangered elements. In this study, an earth-abundant bimetallic catalyst, Cu/Co(OH)x, prepared and optimized by electrodeposition, demonstrates superior ammonia production. Under environmentally relevant conditions of 30 mg NO3−-N L−1, Cu/Co(OH)x showed higher ammonia production than pristine Cu foam with 0.7 and 0.3 mmol NH3 gcat−1 h−1, respectively. The experimental evaluation demonstrated direct reduction and catalytic hydrogenation mechanisms in Cu/Co(OH)x sites. Leaching analyses suggest that Cu/Co(OH)x has outstanding stability with negligible metal concentration below the maximum contaminant level for both Cu and Co. These results provide a framework for using earth-abundant materials in ENR with comparable efficiency and energy consumption to platinum-group materials.

Electron transfer bridge inducing polarization of nitrogen molecules for enhanced photocatalytic nitrogen fixation.

Ammonia (NH3) plays a crucial role in the production of fertilizers, medicines, fibers, etc., which are closely relevant to the development of human society. However, the inert and nonpolar properties of NN seriously hinder artificial nitrogen fixation under mild conditions. Herein, we introduce a novel strategy to enhance the photocatalytic efficiency of N2 fixation through the directional polarization of N2 by rare earth metal atoms, which act as a local "electron transfer bridge." This bridge facilitates the transfer of delocalized electrons to the distal N atom and redirects the polarization of adsorbed N2 molecules. Taking cerium doped BiOCl (Ce-BiOCl) as an example, our results reveal that the electrons transfer to the distal N atom through the cerium atom, resulting in absorbed nitrogen molecular polarization. Consequently, the polarized nitrogen molecules exhibit an easier trend for NN cleavage and the subsequent hydrogenation process, and exhibit a greatly enhanced photocatalytic ammonia production rate of 46.7 μmol g-1 h-1 in cerium doped BiOCl, nearly 4 times higher than that of pure BiOCl. The original concept of directional polarization of N2 presented in this work not only deepens our understanding of the N2 molecular activation mechanism but also broadens our horizons for designing highly efficient catalysts for N2 fixation.

High-performance nitrogen photofixation by Bi2Sn2O7 nanoparticles enriched with oxygen vacancies

Development of effective technologies for artificial nitrogen fixation under mild conditions is of fundamental and technological significance, as the traditional production of NH3 by the Haber-Bosch process entails a high energy consumption and carbon emission. In this study, Bi2Sn2O7 ultrasmall nanoparticles of the pyrochlore phase are synthesized hydrothermally, and the photocatalytic activity towards nitrogen fixation is found to be modulated by the addition of sodium oleate. Among the series, the optimal sample displays a photocatalytic performance with an NH3 production rate of 231 μmol g−1 h−1, due to the formation of a high specific surface area, a large number of active sites for N2 adsorption, and extensive lattice oxygen vacancies. In conjunction with results from first principles calculations, the Bi species around the O2-site oxygen vacancies are found to play a key role in the adsorption and activation of N2. Results from this study highlight the significant potential of Bi2Sn2O7 nanostructures as high-performance catalysts for solar ammonia synthesis. Data AvailabilityData will be made available upon request from the authors.

Designing a Redox Heterojunction for Photocatalytic "Overall Nitrogen Fixation" under Mild Conditions.

Ammonia and nitrates are the most fundamental and significant raw ingredients in human society. Till now, industrial synthetic ammonia by Haber-Bosch process and industrial synthetic nitrates by the Ostwald process have encountered increasingly serious challenges, i.e., high energy consumption, high cost, and environment-harmful gas emissions. Therefore, developing alternative approaches to achieve nitrogen fixation to overcome the inherent deficiencies of the well-established Haber-Bosch and Ostwald processes has fascinated scientists for many years, especially the simultaneous formation of ammonia and nitrate directly from N2 molecules, which has been rarely studied. Herein, a heterojunction-based photocatalytic system is designed to successfully achieve "overall nitrogen fixation," a sustainable and simultaneous conversion of N2 molecules into ammonia and nitrate products under mild conditions. In this heterojunction, interfacial charge redistribution (ICR) promotes selective accumulations of photogenerated electrons and holes in the CdS and WO3 components. As a result, N2 molecules can be activated and reduced to ammonia products with yields of 35.8µmol h-1 g-1 by a multi-electron process, and synchronously oxidized into nitrate products with yields of 14.2µmol h-1 g-1 by a hole-induced oxidation coupling process. This work provides a novel insight and promising approach to realize artificial nitrogen fixation under mild condition.

Plasma-Assisted Dinitrogen Activation via Dual Platinum Cluster Catalysis: A Strategy for Ammonia Synthesis under Mild Conditions

Plasma-Assisted Dinitrogen Activation via Dual Platinum Cluster Catalysis: A Strategy for Ammonia Synthesis under Mild Conditions

In situ localization of BiVO4 onto two-dimensional MXene promoting photoelectrochemical nitrogen reduction to ammonia

The existing industrial ammonia synthesis usually adopts the Haber-Bosch process, which requires harsh conditions of high temperature and high pressure, and consumes high energy. Under this circumstance, photoelectrochemical (PEC) catalysis is regarded as a promising method for N2 reduction reaction (NRR), but bears problems of low efficiency and yield. Thus, exploring active catalysts remains highly desirable. In this work, BiVO4@MXene hybrids have been facilely synthesized by a hydrothermal route. The heterojunctions by the in situ growth of BiVO4 onto two-dimensional (2D) MXene greatly increase the NRR efficiency: under photoelectric conditions, the optimized NH3 yield is 27.25 µg h − 1 cm−2, and the Faraday efficiency achieves 17.54% at −0.8 V relative to the reversible hydrogen electrode (RHE), which are higher than most state-of-the-art NRR (photo) electrocatalysts. The mechanism speculation shows the enhanced light absorption range and the heterojunction formation largely promote the separation and the transfer efficiency of photogenerated carriers, thereby improving the PEC catalytic ability. Therefore, this work provides a hybrid route to combine the advantages of photo and electric catalysis for effective artificial nitrogen fixation.

MXene─A New Paradigm Toward Artificial Nitrogen Fixation for Sustainable Ammonia Generation: Synthesis, Properties, and Future Outlook

Ammonia is a commodity chemical that is manufactured worldwide and supports a growing population. Industrially, ammonia synthesis is dominated by the energy-intensive Haber–Bosch process, thus necessitating the development of a greener approach. Recently, two-dimensional transition-metal carbides/nitrides/carbonitrides, MXenes are emerging as optimistic prospects for the environmentally benign electro- and photocatalytic nitrogen fixation to ammonia. MXenes exhibit excellent hydrophilicity, large specific surface area, superior electrical conductivity, and abundant active sites. Their promising properties for functionalization prosper efficacious enhancement strategies such as co-catalyst loading as well as the formation of MXene-based composites and MXene-derived hybrids. In this Review, the characteristics, fabrication strategies, and applications of MXene-based materials in electrocatalytic and photocatalytic nitrogen fixation, relative to their roles and features, are systematically reviewed. Finally, the current challenges and future directions toward sustainable ammonia generation are provided. This work is expected to deliver valuable insights for the rational engineering of MXene catalysts toward a greener route of ammonia synthesis.

Managing the Nitrogen Cycle via Plasmonic (Photo)Electrocatalysis: Toward Circular Economy.

As renewable energy sources are either intermittent in nature or remote in location, developing cost-effective, sustainable, modular systems and technologies to store and transport renewables at an industrial scale is imperative. Storing cheap renewable electricity into chemical bonds (i.e., chemical energy storage) could be a transformative opportunity for reliable and resilient grid energy storage. This approach enables renewables to be stored and shipped similarly to fossil fuels. Currently, the chemical industry primarily consumes fossil feedstock as an energy source, which has been the standard for over a century. A paradigm shift is required to move toward a more sustainable route for chemical synthesis by electrifying and decarbonizing the modern chemical industry. As renewable electricity costs decrease, (photo)electrosynthesis is gaining interest for synthesizing high-value and high-energy fuels and molecules in a clean, sustainable, and decentralized manner.The nitrogen cycle is one of the Earth's most critical biogeochemical cycles since nitrogen is a vital element for all living organisms. Artificial nitrogen fixation via a (photo)electrochemical system powered by renewables provides an alternative route to resource- and carbon-intensive thermochemical processes. (Photo)electrochemical nitrogen fixation at a large scale necessitates the discovery of active, selective, and stable heterogeneous (photo)electrocatalysts. In addition, the use of advanced in situ and operando spectroscopic techniques is needed to pinpoint the underlying reaction mechanisms. The selectivity of nitrogen (N2) molecules on the catalyst surface and suppressing thermodynamically favorable side reactions (e.g., hydrogen evolution reaction) are the main bottlenecks in improving the rate of (photo)electrochemical nitrogen fixation in aqueous solutions. The rational design of electrode, electrolyte, and reactors is required to weaken the strong nitrogen-nitrogen triple bond (N≡N) at or near ambient conditions. This Account covers our group's recent advances in synthesizing shape-controlled hybrid plasmonic nanoparticles, including plasmonic-semiconductor and plasmonic-transition metal nanostructures with increased surface areas. The nanocatalysts' selectivity and activity toward nitrogen conversion are benchmarked in liquid- and gas-phase electrochemical systems. We leverage operando vibrational-type spectroscopy (i.e., surface-enhanced Raman spectroscopy (SERS)) to identify intermediate species relevant to nitrogen fixation at the electrode-electrolyte interface to gain mechanistic insights into reaction mechanisms, leading to the discovery of more efficient catalysts. Operando SERS revealed that the nitrogen reduction reaction (NRR) to ammonia on hybrid plasmonic-transition metal nanoparticle surfaces (e.g., Pd-Ag) occurs through an associative mechanism. In the NRR process, hydrazine (N2H4) is consumed as an intermediate species. A femtosecond pulsed laser is used to synthesize hybrid plasmonic photocatalysts with homogeneously distributed Pd atoms on a Au nanorod surface, resulting in enhanced optoelectronic and catalytic properties. The overarching goal is to develop modular photoelectrochemical systems for long-duration renewable energy storage. In the context of nitrogen fixation, we aim to propose strategies to manage the nitrogen cycle through the interconversion of N2 and active nitrogen-containing compounds (e.g., NH3, NOx), enabling a circular nitrogen economy with sustainable and positive social and economic outcomes. The versatile approaches presented in this Account can inform future opportunities in (photo)electrochemical energy conversion systems and solar fuel-based applications.