Pothole-rich Ultrathin WO3 Nanosheets that Trigger N≡N Bond Activation of Nitrogen for Direct Nitrate Photosynthesis

Tuning Dynamic Structural Evolution of Bi24O31Cl10 for Enhancing Piezo-Photocatalytic Nitrogen Oxidation to Nitrate

Direct nitrogen oxidation into nitrate under ambient conditions presents a promising strategy for harsh and multistep industrial processes. However, the dynamic structural evolution of active sites in surface reactions constitutes a highly intricate endeavor and remains in its nascent stage. Here, we constructed a Bi24O31Cl10 material with moiré superlattice structure (BCMS) for direct piezo-photocatalytic oxidation of nitrogen into nitrate. Excitingly, BCMS achieved excellent nitric acid production (15.44 mg g-1 h-1) under light and pressure conditions. Detailed experimental results show that the unique structure extracts the local strain tensor from the constricting Bi-Bi bond and Bi-O bond for internal structural reconstruction, which promotes the formation of electron and reactive molecule vortexes to facilitate charge transfer as well as N2 and O2 adsorption. Ultimately, these initiatives strengthen electron exchange between the superoxide radical and nitrogen as well as the binding strength of multiple intermediates, which swayingly adjusts the reaction path and energy barriers.

Interface Engineering-Modulated Nanoscale Bimetallic CoFe-MIL-88A In-Situ-Grown on 2D V2CTx MXene for Electrocatalytic Nitrogen Reduction

The electrochemical nitrogen reduction reaction (eNRR) provides a sustainable green development route for the nitrogen-neutral cycle. In this work, bimetallic CoFe-MIL-88A with two active sites (Fe, Co) were immobilized on a 2D V2CTx MXene surface by in situ growth method to achieve the purpose of the control interface. A large number of heterostructures are formed between small CoFe-MIL-88A and V2CTx, which regulate the electron transfer between the catalyst interfaces. The adsorption and activation of nitrogen on the active sites were enhanced, and the NRR reaction kinetics was accelerated. CoFe-MIL-88A is tightly arranged on V2CTx, which makes CoFe-MIL-88A/V2CTx have better hydrophobicity and can significantly inhibit the hydrogen evolution reaction. The synergistic effect of multicatalytic active sites and multi-interface structure of CoFe-MIL-88A/V2CTx MXene is propitious to nitrogen efficiently and stably to convert into ammonia under environmental conditions with superior selectivity and good catalytic activity. The NH3 yield rate is 29.47 μg h-1 mgcat-1 at -0.3 V vs RHE, and the Faradaic efficiency (FE) is 28.86% at -0.1 V vs RHE. The catalytic mechanism was verified to conform to the distal pathway. This work will provide a new way to develop an MXene-based electrocatalyst for eNRR.

Advances in Catalysts for Urea Electrosynthesis Utilizing CO2 and Nitrogenous Materials: A Mechanistic Perspective

Electrocatalytic urea synthesis from CO2 and nitrogenous substances represents an essential advance for the chemical industry, enabling the efficient utilization of resources and promoting sustainable development. However, the development of electrocatalytic urea synthesis has been severely limited by weak chemisorption, poor activation and difficulties in C-N coupling reactions. In this review, catalysts and corresponding reaction mechanisms in the emerging fields of bimetallic catalysts, MXenes, frustrated Lewis acid-base pairs and heterostructures are summarized in terms of the two central mechanisms of molecule-catalyst interactions as well as chemical bond cleavage and directional coupling, which provide new perspectives for improving the efficiency of electrocatalytic synthesis of urea. This review provides valuable insights to elucidate potential electrocatalytic mechanisms.

Schottky Junctions with Bi@Bi2MoO6 Core-Shell Photocatalysts toward High-Efficiency Solar N2-to-Ammonnia Conversion in Aqueous Phase

The photocatalytic nitrogen reduction reaction (NRR) in aqueous solution is a green and sustainable strategy for ammonia production. Nonetheless, the efficiency of the process still has a wide gap compared to that of the Haber-Bosch one due to the difficulty of N2 activation and the quick recombination of photo-generated carriers. Herein, a core-shell Bi@Bi2MoO6 microsphere through constructing Schottky junctions has been explored as a robust photocatalyst toward N2 reduction to NH3. Metal Bi self-reduced onto Bi2MoO6 not only spurs the photo-generated electron and hole separation owing to the Schottky junction at the interface of Bi and Bi2MoO6 but also promotes N2 adsorption and activation at Bi active sites synchronously. As a result, the yield of the photocatalytic N2-to-ammonia conversion reaches up to 173.40 μmol g-1 on core-shell Bi@Bi2MoO6 photocatalysts, as much as two times of that of bare Bi2MoO6. This work provides a new design for the decarbonization of the nitrogen reduction reaction by the utilization of renewable energy sources.

Hot Carrier Controlled Nitrogen Fixation Reaction in Metal-Free Boron-Anchored Aza-COF: Insight from Nonadiabatic Molecular Dynamics Simulation

Designing highly efficient photocatalysts for the production of renewable energy is a challenging task that necessitates simultaneous control of chemical activity and photocarrier dynamics for a particular reaction. To this end, we have investigated the catalytic mechanism and real-time photocarrier dynamics of the nitrogen reduction reaction (NRR) at the metal-free boron-functionalized 2D aza-COF (B-aza-COF), an inexpensive and environmentally friendly semiconductor. By employing density functional theory (DFT) and time-dependent ab initio nonadiabatic molecular dynamics simulation, we have investigated the electronic structure, light harvesting ability, free energy change, and dynamics of photoexcited carriers. Our calculated results reveal that the gas phase N2 molecule can be effectively reduced into NH3 on B-aza-COF under UV-visible light. Therefore, our investigation on the design of efficient photocatalysts for the nitrogen reduction reaction (NRR) provides a cost-effective opportunity for the sustainable production of NH3.

NiFeB-assisted adsorption and activation of nitrogen to improve the photooxidation activity of zinc porphyrin

This study effectively addresses the challenge of nitrogen adsorption and activation in photocatalytic nitrogen fixation by introducing an oxidizing co-catalyst, NiFeB hydroxides. The NiFeB hydroxides could provide reactive active sites and significantly enhance the nitrogen oxidation activity, offering a novel pathway for co-catalysts in nitrogen fixation reactions.

Electron Storage in Monolayer Tungstate Nanosheets Produced via a Scalable Exfoliation Method

Inorganic nanosheet materials with atomic thinness have been widely studied as (photo)catalytic materials due to their unique electronic states and surface structures. One scalable and reproducible method of producing monolayer nanosheets is a top-down approach based on the exfoliation of layered parent compounds using an alkylammonium solution as a surfactant. However, H2W2O7 layered tungstates dissolve in basic aqueous solutions, making them unsuitable for the exfoliation process. This work proposes a scalable method to obtain monolayer WO3 nanosheets with a very high external field responsiveness. This work shows that H2W2O7 topochemically swells in a concentrated octylamine (C8N17NH2) aqueous solution with a concentration above the solubility of octylamine in water. Water was added for exfoliation of the liquid crystalline phase into isolated W2O72- nanosheets with octylammonium (C8N17NH3+) protection. Crystalline WO3 nanosheets on the n-Si substrate obtained with calcination exhibited electron richness in the conduction band due to static electron transfer at the interface.

Synergy of Pd2+/S2--Doped TiO2 Supported on 2-Methylimidazolium-Functionalized Polypyrrole/Graphene Oxide for Enhanced Nitrogen Electrooxidation

The electrosynthesis of nitrate catalyzed by electrochemical nitrogen oxidation reaction (NOR) is considered as an alternative and sustainable approach to the conventional industrial manufacture, but optimizing the electrocatalytic NOR performance and fabricating the efficient NOR electrocatalysts at the design level still encounter great challenges. Herein, unique Pd2+- and S2--doped TiO2 (Pb/S-TiO2) nanoparticles are successfully in situ grown on the surface of 2-methylimidazolium-functionalized polypyrrole/graphene oxide (2-MeIm/PPy/GO), which present the typical hierarchical micro-nanostructures, resulting in the excellent electrocatalytic NOR performance with the highest NO3 - yield of 72.69 µg h-1 mg-1 act. and the maximum Faraday efficiency of 8.92% at 2.04 V (vs reversible hydrogen electrode) due to the synergistic effect of each component. Due to the doping effect, the appropriate oxygen evolution reaction (OER) activity is achieved by Ti-site, where OER principally occurs, providing *O during the non-electrochemical step of NOR, while the electrocatalytic NOR process as the electrochemical conversion of inert N2 to active *NO intermediates mainly occurs at the Pd-site. Especially, the sulfate radicals in situ formed on Pb/S-TiO2@2-MeIm/PPy/GO further promote nitrogen adsorption and decrease the reaction energy barrier, resulting in the acceleration of NOR. It provides theoretical and practical experience for the design and preparation of NOR electrocatalysts.

Catalytic Ozonation of Air toward Direct Nitric Acid Production Using Hierarchical Co3O4 with a Tunable Microstructure

The nitrogen oxidation reaction (NOR) to form nitric acid by applying natural air and H2O under ambient conditions is a sustainable approach to achieving efficient and selective N2 fixation for industrial applications. In this study, four kinds of Co3O4 catalysts with a controllable microstructure were prepared to catalyze the direct NOR of N2 in the air. At the same time, the reaction mechanism of the conversion of N2 to nitric acid under catalytic ozonation was explored through experimental research and density functional theory (DFT) calculation. The results showed that the prepared porous nanosheets self-assembled into microflower-structured samples. The HCOF showed extraordinary catalytic performance for direct NOR to produce a high concentration of nitric acid. The maximum rate of nitric acid formation could be as high as 6.67 mmol/(h·gcat), which was higher than those of most reported photocatalytic or electrocatalytic N2 fixation processes for direct NOR to produce NO3-. Furthermore, the 15N isotopic-labeling experiment confirmed that the produced NO3- originated from N2 in the air by the direct NOR process. In the direct NOR mechanism, inert N2 molecules were captured at the Co3+ active sites by the acceptance-donation electron conduction mode, and the oxygen vacancies boosted the chemical adsorption of N2 molecules and greatly reduced the activation energy barrier of N2 molecules. The active free radicals •OH and •O2- generated by the decomposition of O3 molecules oxidized N2 to the intermediate *NO, which was the rate-determining step, and it was then absorbed by water to form nitric acid. The air catalytic ozonation method in this study was proposed as a facile pathway for efficient nitrogen fixation. This research provides a new method for environmental protection and efficient production of nitric acid at distributed sources.

Perovskite Oxide as A New Platform for Efficient Electrocatalytic Nitrogen Oxidation

Electrocatalytic nitrogen oxidation reaction (NOR) offers an efficient and sustainable approach for conversion of widespread nitrogen (N2 ) into high-value-added nitrate (NO3 - ) under mild conditions, representing a promising alternative to the traditional approach that involves harsh Haber-Bosch and Ostwald oxidation processes. Unfortunately, due to the weak absorption/activation of N2 and the competitive oxygen evolution reaction, the kinetics of NOR process is extremely sluggish accompanied with low Faradaic efficiencies and NO3 - yield rates. In this work, an oxygen-vacancy-enriched perovskite oxide with nonstoichiometric ratio of strontium and ruthenium (denoted as Sr0.9 RuO3 ) was synthesized and explored as NOR electrocatalyst, which can exhibit a high Faradaic efficiency (38.6 %) with a high NO3 - yield rate (17.9 μmol mg-1  h-1 ). The experimental results show that the amount of oxygen vacancies in Sr0.9 RuO3 is greatly higher than that of SrRuO3 , following the same trend as their NOR performance. Theoretical simulations unravel that the presence of oxygen vacancies in the Sr0.9 RuO3 can render a decreased thermodynamic barrier toward the oxidation of *N2 to *N2 OH at the rate-determining step, leading to its enhanced NOR performance.

Dual-Plasmon Resonance Coupling Promoting Directional Photosynthesis of Nitrate from Air

Photocatalysis, particularly plasmon-mediated photocatalysis, offers a green and sustainable approach for direct nitrogen oxidation into nitrate under ambient conditions. However, the unsatisfactory photocatalytic efficiency caused by the limited localized electromagnetic field enhancement and short hot carrier lifetime of traditional plasmonic catalysts is a stumbling block to the large-scale application of plasmon photocatalytic technology. Herein, we design and demonstrate the dual-plasmonic heterojunction (Bi/Csx WO3 ) achieves efficient and selective photocatalytic N2 oxidation. The yield of NO3 - over Bi/Csx WO3 (694.32 μg g-1  h-1 ) are 2.4 times that over Csx WO3 (292.12 μg g-1  h-1 ) under full-spectrum irradiation. The surface dual-plasmon resonance coupling effect generates a surge of localized electromagnetic field intensity to boost the formation efficiency and delay the self-thermalization of energetic hot carriers. Ultimately, electrons participate in the formation of ⋅O2 - , while holes involve in the generation of ⋅OH and the activation of N2 . The synergistic effect of multiple reactive oxygen species drives the direct photosynthesis of NO3 - , which achieves the overall-utilization of photoexcited electrons and holes in photocatalytic reaction. The concept that the dual-plasmon resonance coupling effect facilitates the directional overall-utilization of photoexcited carriers will pave a new way for the rational design of efficient photocatalytic systems.

Comprehensive Insights into the Family of Atomically Thin 2D-Materials for Diverse Photocatalytic Applications

2D materials with their fascinating physiochemical, structural, and electronic properties have attracted researchers and have been used for a variety of applications such as electrocatalysis, photocatalysis, energy storage, magnetoresistance, and sensing. In recent times, 2D materials have gained great momentum in the spectrum of photocatalytic applications such as pollutant degradation, water splitting, CO2 reduction, NH3 production, microbial disinfection, and heavy metal reduction, thanks to their superior properties including visible light responsive band gap, improved charge separation and electron mobility, suppressed charge recombination and high surface reactive sites, and thus enhance the photocatalytic properties rationally as compared to 3D and other low-dimensional materials. In this context, this review spot-lights the family of various 2D materials, their properties and their 2D structure-induced photocatalytic mechanisms while giving an overview on their synthesis methods along with a detailed discussion on their diverse photocatalytic applications. Furthermore, the challenges and the future opportunities are also presented related to the future developments and advancements of 2D materials for the large-scale real-time photocatalytic applications.

The role of 13X molecular sieves in photocatalytic nitrogen fixation

To overcome the weak adsorption and difficult activation of N2 on catalysts in the photocatalytic nitrogen reduction reaction (NRR), we put forward that the introduction of molecular sieve 13X may realize the enrichment and activation of N2. 13X and the photoactive substrate BiOBr were assembled electrostatically to construct composite catalysts. In the presence of 13X, they are rich in nitrogen adsorption and activation sites, and the highest ammonia yield can reach 360.5 μmol h-1 gcat-1. It is surprising to find that 13X is able to optimize the photoelectric properties. This work extends the function of molecular sieves in the NRR and offers guidance to design catalysts with high photocatalytic activity.

Selective Electrocatalytic Oxidation of Nitrogen to Nitric Acid Using Manganese Phthalocyanine

Ammonia is produced through the energy-intensive Haber-Bosch process, which undergoes catalytic oxidation for the production of commercial nitric acid by the senescent Ostwald process. The two energy-intensive industrial processes demand for process sustainability. Hence, single-step electrocatalysis offers a promising approach toward a more environmentally friendly solution. Herein, we report a 10-electron pathway associated one-step electrochemical dinitrogen oxidation reaction (N₂OR) to nitric acid by manganese phthalocyanine (MnPc) hollow nano-structures under ambient conditions. The catalyst delivers a nitric acid yield of 513.2 μmol h^-1 g_cat^-1 with 33.9% Faradaic efficiency @ 2.1 V versus reversible hydrogen electrode. The excellent N₂OR performances are achieved due to the specific-selectivity, presence of greater number of exposed active sites, recyclability, and long period stability. The extended X-ray absorption fine structure confirms that Mn atoms are coordinated to the pyrrolic and pyridinic nitrogen via Mn-N₄ coordination. Density functional theory-based theoretical calculations confirm that the Mn-N₄ site of MnPc is the main active center for N₂OR, which suppresses the oxygen evolution reaction. This work provides a new arena about the successful example of one step nitric acid production utilizing a Mn-N₄ active site-based metal phthalocyanine electrocatalyst by dinitrogen oxidation for the development of a carbon-neutral sustainable society.

Chelated Ion-Exchange Strategy toward BiOCl Mesoporous Single-Crystalline Nanosheets for Boosting Photocatalytic Selective Aromatic Alcohols Oxidation

The photoresponse and photocatalytic efficiency of bismuth oxychloride (BiOCl) are greatly limited by rapid recombination of photogenerated carriers. The construction of porous single-crystal BiOCl photocatalyst can effectively alleviate this issue and provide accessible active sites. Herein, a facile chelated ion-exchange strategy is developed to synthesize BiOCl mesoporous single-crystalline nanosheets (BiOCl MSCN) using acetic acid and ammonia solution respectively as chelating agent and ionization promoter. The strong chelation between acetate ions and Bi³⁺ ions introduces acetate ions into the precipitated product to exchange with Cl^- ions, resulting in large lattice mismatch, strain release, and formation of void-like mesopores. The prepared BiOCl MSCN photocatalyst exhibits excellent catalytic performance with 99% conversion and 98% selectivity for oxidation of benzyl alcohol to benzaldehyde and superior general adaptability for various aromatic alcohols. The theoretical calculations and characterizations confirm that the superior performance is mainly attributed to the abundant oxygen vacancies, plenty of accessible adsorption/active sites and fast charge transport path without grain boundaries.

Construction of g-C3N4/CdS/BiVO4 ternary nanocomposite with enhanced visible-light-driven photocatalytic activity toward methylene blue dye degradation in the aqueous phase

Herein, the ternary CdS/BiVO₄/g-C₃N₄ (CBG) hybrid semiconductor photocatalyst was prepared via a hydrothermal technique. The synthesized photocatalysts were thoroughly characterized using powder XRD, XPS, FTIR, SEM, TEM, and UV-DRS to investigate the microstructural, morphological attributes, and optical properties. The photocatalytic activity of the ternary CBG hybrid semiconductor was assessed through the photodegradation of Methylene Blue (MB) aqueous dye under visible light. The outcomes exhibited that the CBG hybrid semiconductor showed excellent photocatalytic activity (about 94.5% after 120 min) compared to the results obtained with the pristine materials or the other composite (CdS/BiVO₄). The enhancement of photocatalytic activity can be due to the construction of heterojunctions among g-C₃N₄, CdS, and BiVO₄, which improves charge transfer efficiency and hence favors the degradation of organic dyes. Moreover, the as-prepared photocatalyst showed excellent stability after five cycles, indicating good stability and reusability. Subsequently, a possible photocatalytic mechanism was proposed based on the experimental results. The current investigation provides a promising strategy to promote photocatalytic activity to eliminate waterborne contaminants.

Defect-induced charge redistribution of MoO3-x nanometric wires for photocatalytic ammonia synthesis

Photocatalytic ammonia synthesis technology has become one of the effective methods to replace the Haber method for nitrogen fixation in the future for its low energy consumption and green environment. However, limited by the weak adsorption/activation ability of N₂ molecules at the photocatalyst interface, the efficient nitrogen fixation still remains a daunting job. Defect-induced charge redistribution as a catalytic site for N₂ molecules is the most prominent strategy to enhance the adsorption/activation of N₂ molecules at the interface of catalysts. In this study, MoO_3-x nanowires containing asymmetric defects were prepared by a one-step hydrothermal method via using glycine as a defect inducer. It is shown that at the atomic scale, the defect-induced charge reconfiguration can significantly improve the nitrogen adsorption and activation capacity and enhance the nitrogen fixation capacity; at the nanoscale, the charge redistribution induced by asymmetric defects effectively improved the photogenerated charge separation. Given the charge redistribution on the atomic and nanoscale of MoO_3-x nanowires, the optimal nitrogen fixation rate of MoO_3-x reached 200.35 µmol g^-1h^-1.

Synergistic role of hydrogen treatment and heterojunction in H-WO3-x/TiO2-x NT/Ti foil-based photoanodes for photoelectrochemical wastewater detoxification and antibacterial activity

The process of photoelectrochemical wastewater detoxification is limited by significant charge recombination, which is difficult to suppress with efficient single-material photoanodes. We demonstrated the effectiveness of hydrogen treatment in evaluating charge separation properties in WO_3-x/TiO_2-x NT/Ti foil heterojunction photoanodes. The influence of varying hydrogen annealing (200-400 °C) on the structural and photoelectrochemical properties of WO₃/TiO₂ NS/NT heterojunction is studied systematically. Additionally, after hydrogen treatment of pristine WO₃/TiO₂ NT/Ti foil photoanodes, substoichiometric H-WO_3-x/TiO_2-x NT-300 achieved the 1.21 mA/cm² photocurrent density, which is 8.06 and 3.27 times than TiO₂ NT and WO₃/TiO₂ NT. The hydrogen-treated H-WO_3-x/TiO_2-x NT-300 electrode exhibits 3 times greater bulk efficiencies than the WO₃/TiO₂ NT electrode due to the production of oxygen vacancies at the interface. Additionally, optimum H-WO_3-x/TiO_2-x NS/NT-300 photoanode exhibited 93.8% E. coli and 99.8% BPA decomposition efficiencies. The present work shows the effectiveness of microwave-assisted H-WO_3-x/TiO_2-x NT heterojunction photoanodes for organic decomposition and antibacterial activity in a neutral environment without surface-loaded co-catalysts.

Free radicals promote electrocatalytic nitrogen oxidation

In this work, we introduce hydroxyl radicals into the electrocatalytic nitrogen oxidation reaction (NOR) for the first time. Cobalt tetroxide (Co₃O₄) acts not only as an electrocatalyst, but also as a nanozyme (in combination with hydrogen peroxide producing ˙OH), and can be used as a high-efficiency nitrogen oxidation reaction (NOR) electrocatalyst for environmental nitrate synthesis. Co₃O₄ + ˙OH shows an excellent nitrogen oxidation reaction (NOR) performance among Co₃O₄ catalysts in 0.1 M Na₂SO₄ solution. At an applied potential of 1.7 V vs. RHE, the HNO₃ yield of Co₃O₄ + ˙OH reaches 89.35 μg h^-1 mg_cat ^-1, which is up to 7 times higher than that of Co₃O₄ (12.8 μg h^-1 mg_cat ^-1) and the corresponding FE is 20.4%. The TOF of Co₃O₄ + ˙OH at 1.7 V vs. RHE reaches 0.58 h^-1, which is higher than that of Co₃O₄ (0.083 h^-1), demonstrating that free radicals greatly enhance the intrinsic activity. Density functional theory (DFT) demonstrates that ˙OH not only can drive nitrogen adsorption, but also can decrease the energy barrier (rate-determining step) of N₂ to N₂OH*, thus producing great NOR activity.

High-Performance Photocatalytic Reduction of Nitrogen to Ammonia Driven by Oxygen Vacancy and Ferroelectric Polarization Field of SrBi4 Ti4 O15 Nanosheets

Photo-responsive semiconductors can facilitate nitrogen activation and ammonia production, but the high recombination rate of photogenerated carriers represents a significant barrier. Ferroelectric photocatalysts show great promise in overcoming this challenge. Herein, by adopting a low-temperature hydrothermal procedure with varying concentrations of glyoxal as the reducing agent, oxygen vacancies (Vo) are effectively produced on the surface of ferroelectric SrBi₄ Ti₄ O₁₅ (SBTO) nanosheets, which leads to a considerable increase in photocatalytic activity toward nitrogen fixation under simulated solar light with an ammonia production rate of 53.41 µmol g^-1 h^-1 , without the need of sacrificial agents or photosensitizers. This is ascribed to oxygen vacancies that markedly enhance the self-polarization and internal electric field of ferroelectric SBTO, and hence, facilitate the separation of photogenerated charge carriers and light trapping as well as N₂ adsorption and activation, as compared to pristine SBTO. Consistent results are obtained in theoretical studies. Results from this study highlight the significance of surface oxygen vacancies in enhancing the performance of photocatalytic nitrogen fixation by ferroelectric catalysts.

Understanding Aerobic Nitrogen Photooxidation on Titania through In Situ Time-Resolved Spectroscopy

Nitrate is an important raw material for chemical fertilizers, but it is industrially manufactured in multiple steps at high temperature and pressure, urgently motivating the design of a green and sustainable strategy for nitrate production. We report the photosynthesis of nitrate from N₂ and O₂ on commercial TiO₂ in a flow reactor under ambient conditions. The TiO₂ photocatalyst offered a high nitrate yield of 1.85 μmol h^-1 as well as a solar-to-nitrate energy conversion efficiency up to 0.13 %. We combined reactivity and in situ Fourier transform infrared spectroscopy to elucidate the mechanism of nitrate formation and unveil the special role of O₂ in N≡N bond dissociation. The mechanistic insight into charge-involved N₂ oxidation was further demonstrated by in situ transient absorption spectroscopy and electron paramagnetic resonance. This work exhibits the mechanistic origin of N₂ photooxidation and initiates a potential method for triggering inert catalytic reactions.

Recent progress of photocatalysts based on tungsten and related metals for nitrogen reduction to ammonia

Photocatalytic nitrogen reduction reaction (NRR) to ammonia holds a great promise for substituting the traditional energy-intensive Haber–Bosch process, which entails sunlight as an inexhaustible resource and water as a hydrogen source under mild conditions. Remarkable progress has been achieved regarding the activation and solar conversion of N₂ to NH₃ with the rapid development of emerging photocatalysts, but it still suffers from low efficiency. A comprehensive review on photocatalysts covering tungsten and related metals as well as their broad ranges of alloys and compounds is lacking. This article aims to summarize recent advances in this regard, focusing on the strategies to enhance the photocatalytic performance of tungsten and related metal semiconductors for the NRR. The fundamentals of solar-to-NH₃ photocatalysis, reaction pathways, and NH₃ quantification methods are presented, and the concomitant challenges are also revealed. Finally, we cast insights into the future development of sustainable NH₃ production, and highlight some potential directions for further research in this vibrant field.

Density Embedding Method for Nanoscale Molecule-Metal Interfaces

In this work, we extend the applicability of standard Kohn-Sham DFT (KS-DFT) to model realistically sized molecule-metal interfaces where the metal slabs venture into the tens of nanometers in size. Employing state-of-the-art noninteracting kinetic energy functionals, we describe metallic subsystems with orbital-free DFT and combine their electronic structure with molecular subsystems computed at the KS-DFT level resulting in a multiscale subsystem DFT method. The method reproduces within a few millielectronvolts the binding energy difference of water and carbon dioxide molecules adsorbed on the top and hollow sites of an Al(111) surface compared to KS-DFT of the combined supersystem. It is also robust for Born-Oppenheimer molecular dynamics simulations. Very large system sizes are approached with standard computing resources thanks to a parallelization scheme that avoids accumulation of memory at the gather-scatter stage. The results as presented are encouraging and open the door to ab initio simulations of realistically sized, mesoscopic molecule-metal interfaces.

NiPS3 ultrathin nanosheets as versatile platform advancing highly active photocatalytic H2 production

High-performance and low-cost photocatalysts play the key role in achieving the large-scale solar hydrogen production. In this work, we report a liquid-exfoliation approach to prepare NiPS₃ ultrathin nanosheets as a versatile platform to greatly improve the light-induced hydrogen production on various photocatalysts, including TiO₂, CdS, In₂ZnS₄ and C₃N₄. The superb visible-light-induced hydrogen production rate (13,600 μmol h^-1 g^-1) is achieved on NiPS₃/CdS hetero-junction with the highest improvement factor (~1,667%) compared with that of pure CdS. This significantly better performance is attributed to the strongly correlated NiPS₃/CdS interface assuring efficient electron-hole dissociation/transport, as well as abundant atomic-level edge P/S sites and activated basal S sites on NiPS₃ ultrathin nanosheets advancing hydrogen evolution. These findings are revealed by the state-of-art characterizations and theoretical computations. Our work for the first time demonstrates the great potential of metal phosphorous chalcogenide as a general platform to tremendously raise the performance of different photocatalysts.

Water-resistant organic-inorganic hybrid perovskite quantum dots activated by the electron-deficient d-orbital of platinum atoms for nitrogen fixation

Due to their special physicochemical properties, organic-inorganic hybrid perovskite quantum dots (OIP QDs) are ideal and potential catalysts for the nitrogen reduction reaction (NRR). However, the OIP QD-based NRR is limited by poor water resistance, competitive suppression by the hydrogen evolution reaction, and inefficient active sites on the catalyst surfaces. Herein, to ensure an efficient NRR in aqueous solution, a water-resistant polycarbonate-part-encapsulated heterojunction of Zn,Pt^IV co-doped PbO-MAPbBr₃ (Pt^IV/Zn/PbO/PC-Zn/MAPbBr₃) is prepared through one-step electrospray-based microdroplet synthesis. Confirmed by both experimental and theoretical examinations, PbO is exposed on the PC-part-encapsulated surface to construct a Type I heterojunction. This heterojunction is further improved by synergistic co-doping with Pt^IV to facilitate efficient electron transfer for efficient photocatalysis of the NRR. Due to the active sites of the d-orbital electron-deficient Pt atoms (exhibiting a lower reaction energy barrier and highly selective N₂ adsorption), the ammonia yield rate is 40 times higher than that without doping. This work initiates and develops on the application of OIP QDs in the NRR.

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 35.8 µmol h^-1 g^-1 by a multi-electron process, and synchronously oxidized into nitrate products with yields of 14.2 µmol 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.

Sulfate-Enabled Nitrate Synthesis from Nitrogen Electrooxidation on a Rhodium Electrocatalyst

The electrocatalytic nitrogen oxidation reaction (NOR) to generate nitrate is gaining increasing attention as an alternative approach to the conventional industrial manufacture. But, current progress in NOR is limited by the difficulties in activation and conversion of the strong N≡N bond (941 kJ mol^-1 ). Herein, we designed to utilize sulfate to enhance NOR performance over an Rh electrocatalyst. After the addition of sulfate, the inert Rh nanoparticles exhibited superior NOR performance with a nitrate yield of 168.0 μmol g_cat ^-1  h^-1 . The ¹⁵ N isotope-labeling experiment confirmed the produced nitrate from nitrogen electrooxidation. A series of electrochemical in situ characterizations and theoretical calculation unveiled that sulfate promoted nitrogen adsorption and decreased the reaction energy barrier, and in situ formed sulfate radicals reduced the activation energy of the potential-determining step, thus accelerating NOR.

Quantitative Evaluation of Carrier Dynamics in Full-Spectrum Responsive Metallic ZnIn2S4 with Indium Vacancies for Boosting Photocatalytic CO2 Reduction

The influence of defects on quantitative carrier dynamics is still unclear. Therefore, full-spectrum responsive metallic ZnIn₂S₄ (V_In-rich-ZIS) rich in indium vacancies and exhibiting high CO₂ photoreduction efficiency was synthesized for the first time. The influence of the defects on the carrier dynamic parameters was studied quantitatively; the results showed that the minority carrier diffusion length (L_D) is closely related to the catalytic performance. In situ infrared spectroscopy and theoretical calculations revealed that the presence of indium vacancies lowers the energy barrier for CO₂ to CO conversion via the COOH* intermediate. Hence, the high rate of CO evolution reaches 298.0 μmol g^-1 h^-1, a nearly 28-fold enhancement over that with ZnIn₂S₄ (V_In-poor-ZIS), which is not rich in indium vacancies. This work fills the gaps between the catalytic performance of defective photocatalysts and their carrier dynamics and may offer valuable insight for understanding the mechanism of photocatalysis and designing more efficient defective photocatalysts.

Exposed Mo atoms induced by micropores enhanced H2S sensing of MoO3 nanoflowers

It is well known that the metal atoms of metal oxide semiconductor (MOS) exhibit significant activity in gas sensing. However, limited by the shielding effect of the outer oxygen atom layer, layered MoO₃ is often difficult to show ideal gas adsorption activity. Hence, the MoO₃ microporous nanoflowers (MPNFs) assembled by porous two-dimensional nanosheets were successfully synthesized and exhibited excellent gas sensing performance to H₂S, and the response was 7.2 times higher than that of simple MoO₃ nanosheets. The abundant pores of MoO₃ MPNFs were due to the influence of the crystal cell shrinkage effect on the atomic arrangement, while the significantly enhanced gas sensing performance was attributed to the positive effect of the microporous structure on gas diffusion and the exposed edge Mo atoms. This was confirmed by DFT calculation results that, compared to the Mo atoms on the surface of MoO₃ nanosheets, the Mo atoms around the pores were exposed because they broke through the shielding effect of the oxygen atom layer and exhibited higher adsorption activity for H₂S and O₂ molecules. Therefore, this work can shed a light on the design of high-performance gas sensors based on metal oxides.

Catalytic Kinetics Regulation for Enhanced Electrochemical Nitrogen Oxidation by Ru-Nanoclusters-Coupled Mn3 O4 Catalysts Decorated with Atomically Dispersed Ru Atoms

Electrochemical N₂ oxidation reaction (NOR), using water and N₂ in the atmosphere, represents a sustainable approach for nitric production to replace the conventional industrial synthesis with high energy consumption and greenhouse gas emission. Meanwhile, owing to chemical inertness of N₂ and sluggish kinetics for 10-electron transfer, emerging electrocatalysts remain largely underexplored. Herein, Ru-nanoclusters-coupled Mn₃ O₄ catalysts decorated with atomically dispersed Ru atoms (Ru-Mn₃ O₄ ) are designed and explored as an advanced electrocatalyst for ambient N₂ oxidation, with an excellent Faraday efficiency (28.87%) and a remarkable NO₃ ^- yield (35.34 µg h^-1 mg^-1 _cat. ), respectively. Experiments and density functional theory calculations reveal that the outstanding activity is ascribed to the coexistence of Ru clusters and single-atom Ru. The synergistic effect between the Ru clusters and Mn₃ O₄ can effectively activate the chemically inert N₂ , lowering the kinetic barrier for the vital breakage of N≡N. The intensive *OH supply and enhanced conductivity are used to regulate the catalytic kinetics for optimized performance. This work provides brand-new ideas for the rational design of electrocatalysts in complicated electrocatalytic reactions with multiple dynamics-different steps.

Direct conversion of N2 and O2: status, challenge and perspective

As key components of air, nitrogen (N₂) and oxygen (O₂) are the vital constituents of lives. Synthesis of NO₂, and C-N-O organics direct from N₂ and O₂, rather than from an intermediate NH₃ (known as the Haber-Bosch process), is tantalizing. However, the extremely strong N≡N triple bond (945 kJ mol^-1) and the nonpolar stable electron configuration of dinitrogen lead to its conversion being extensively energy demanding. The further selective synthesis of high-value C-N-O organics directly from N₂, O₂ and C-containing molecules is attractive yet greatly challenging from both scientific and engineering perspectives. Enormous efforts have been dedicated to the direct conversion of N₂ and O₂ via traditional and novel techniques, including thermochemical, plasma, electrochemical, ultrasonic and photochemical conversion. In this review, we aim to provide a thorough comprehension of the status and challenge of the direct conversion of N₂, O₂ and C-containing molecules (particularly N₂ and O₂). Moreover, we will propose some future perspectives to stimulate more inspiration from the scientific community to tackle the scientific and engineering challenges.

Subnanometric alkaline-earth oxide clusters for sustainable nitrate to ammonia photosynthesis

The limitation of inert N₂ molecules with their high dissociation energy has ignited research interests in probing other nitrogen-containing species for ammonia synthesis. Nitrate ions, as an alternative feedstock with high solubility and proton affinity, can be facilely dissociated for sustainable ammonia production. Here we report a nitrate to ammonia photosynthesis route (NO₃⁻RR) catalyzed by subnanometric alkaline-earth oxide clusters. The catalyst exhibits a high ammonia photosynthesis rate of 11.97 mol g_metal⁻¹ h⁻¹ (89.79 mmol g_cat⁻¹ h⁻¹) with nearly 100% selectivity. A total ammonia yield of 0.78 mmol within 72 h is achieved, which exhibits a significant advantage in the area of photocatalytic NO₃⁻RR. The investigation of the molecular-level reaction mechanism reveals that the unique active interface between the subnanometric clusters and TiO₂ substrate is beneficial for the nitrate activation and dissociation, contributing to efficient and selective nitrate reduction for ammonia production with low energy input. The practical application of NO₃⁻RR route in simulated wastewater is developed, which demonstrates great potential for its industrial application. These findings are of general knowledge for the functional development of clusters-based catalysts and could open up a path in the exploitation of advanced ammonia synthesis routes with low energy consumption and carbon emission.

Photocatalytic reduction of waste nitrate offers an alternative route for ammonia production. Here the authors report BaO clusters on TiO2 for nitrate-ammonia photosynthesis with high ammonia yield.

Enhanced Structural Stability and Volumetric Capacity of a 3D Pyknotic Graphene Conductive Network via a Pillar Effect of Sn Nanoparticles for Sodium-Ion Batteries

High volumetric capacity and durability anode materials for sodium ion batteries have been urgently required for practical applications. Herein, we reported a Sn-pillared pyknotic graphene conductive network with high-level N-doping. This densely stacked block offers high volumetric Na-ion storage capacity, rapid electrochemical reaction kinetics, and robust structural stability during cycling owing to the high capacity component (metallic Sn ≈847 mAh g^-1), high tap density (≈2.63 g cm^-3), high conductivity (N doping ≈5 at. %), and strong spatially confined and pillared structure. Moreover, theoretical simulations have indicated that the charge accumulation around the N-doped region is more pronounced compared to the pristine one, and electrons accumulate around the N atom while loss occurs at the Na atom. These studies also suggest that it might possibly contribute to higher conductivity and stronger electrophilic reactivity, thereby resulting in enhanced Na-ion storage performance. As a result, the as-obtained electrode material exhibits competitive volumetric capacity (1462 mAh cm^-3 at 0.1 A g^-1), cycling performance (1207 mAh cm^-3 after 100 cycles), and promising rate behavior simultaneously.

Progress in Mo/W-based electrocatalysts for nitrogen reduction to ammonia under ambient conditions

Ammonia (NH₃), possessing high hydrogen content and energy density, has been widely employed for fertilizers and value-added chemicals in green energy carriers and fuels. However, the current NH₃ synthesis largely depends on the traditional Haber-Bosch process, which needs tremendous energy consumption and generates greenhouse gas, resulting in severe energy and environmental issues. The electrochemical strategy of converting N₂ to NH₃ under mild conditions is a potentially promising route to realize an environmentally friendly concept. Among various catalysts, molybdenum/tungsten-based electrocatalysts have been widely used in electrochemical catalytic and energy conversion. This review describes the latest progress of molybdenum/tungsten-based electrocatalysts for the electrochemical nitrogen reduction reaction. The fundamental roles of morphology, doping, defects, heterojunction, and coupling regulation in improving electrocatalytic performance are mainly discussed. Besides, some tailoring strategies for enhancing the conversion efficiency of N₂ to NH₃ over Mo/W-based electrocatalysts are also summarized. Finally, the existing challenges and limitations of N₂ fixation are proposed, as well as possible future perspectives, which will provide a platform for further development of advanced Mo/W-based N₂ reduction systems.

Edge-Site-Rich Ordered Macroporous BiOCl Triggers CO Activation for Efficient CO2 Photoreduction

Endowing a semiconductor with tunable edge active sites will effectively enhance catalytic performance. Herein, an edge-site-rich ordered macroporous BiOCl (BiOCl-P) with abundant dangling bonds is constructed via the colloidal crystal template method. The edge-site-rich ordered macroporous structure provides abundant adsorption sites for CO₂ molecules, as well as forms numerous localized electron enrichment areas, accelerating charge transfer. DFT calculations reveal that the dangling bonds-rich configuration can effectively reduce the CO₂ activation energy barrier, boost the CO double bond dissociation, and facilitate the proton electron coupling reaction. As a result, the BiOCl-P achieves a higher CO and CH₄ generation rate of 78.07 and 3.03 µmol g^-1 under 4 h Xe lamp irradiation in a solid-gas system. Finally, the CO₂ molecules' conversion process is further investigated by in situ Fourier-transform infrared spectroscopy. This work realizes a new avenue toward the design of vibrant semiconductors on the nanoscale to boost inert CO₂ photoreduction.

Visible-light-driven photocatalytic N2 fixation to nitrates by 2D/2D ultrathin BiVO4 nanosheet/rGO nanocomposites

Photocatalytic nitrogen fixation is a promising approach owing to its environmental friendliness and cost-effectiveness. The 2D/2D BiVO₄/rGO hybrid developed in this study exhibits a high nitrate-production rate of 1.45 mg h^-1 g^-1 and an apparent quantum efficiency (QE) of 0.64% at 420 nm, which represents one of the most highly active photocatalysts reported thus far.

Sustainable nitrate production out of thin air: the photocatalytic oxidation of molecular nitrogen

Dinitrogen can be photocatalytically oxidized by TiO2 to nitrogen oxides and nitrates. This enables the sustainable production of fixed nitrogen essentially from thin air using sunlight.