A perovskite La2Ti2O7 nanosheet as an efficient electrocatalyst for artificial N2 fixation to NH3 in acidic media

Recent Developments of Dual Single-Atom Catalysts for Nitrogen Reduction Reaction

Ammonia is vital for fertilizer production, hydrogen storage, and alternative fuels. The conventional Haber-Bosch process for ammonia production is energy-intensive and environmentally harmful. Designing environmentally friendly and low-energy consumption strategies for electrocatalytic N2 reduction reaction (ENRR) in mild conditions is meaningful. Single-atom catalysts (SACs) have been studied extensively for NRR due to their high atomic utilization and unique electronic structure but are limited by their poor faradic efficiency and low ammonia formation yield. Dual single-atom catalysts (DSACs) have recently emerged as a promising solution for the effective activation of molecular N2 , providing diverse active sites and synergistic interactions between adjacent atoms. In this review, we summarize the latest advances in metal DSACs for electrochemical ENRR based on both theoretical calculations and experimental studies, including aspects such as their variety, coordination, support, N2 adsorption and activity mechanisms, the characterization of NRR and electrochemical cell Configuration. We also address challenges and prospects in this rapidly evolving field, providing a comprehensive overview of DSACs for ENRR.

Oxygen vacancies engineering in electrocatalysts nitrogen reduction reaction

Ammonia is important, both as a fertilizer and as a carrier of clean energy, mainly produced by the Haber-Bosch process, which consumes hydrogen and emits large amounts of carbon dioxide. The ENRR (Electronchemical Nitrogen Reduction Reaction) is considered a promising method for nitrogen fixation owing to their low energy consumption, green and mild. However, the ammonia yield and Faraday efficiency of the ENRR catalysts are low due to the competitive reaction between HER and NRR, the weak adsorption of N2 andthe strong N≡N triple bond. Oxygen vacancy engineering is the most important method to improve NRR performance, not only for fast electron transport but also for effective breaking of the N≡N bond by capturing metastable electrons in the antibonding orbitals of nitrogen molecules. In this review, the recent progress of OVs (oxygen vacancies) in ENRR has been summarized. First, the mechanism of NRR is briefly introduced, and then the generation methods of OVs and their applicationin NRR are discussed, including vacuum annealing, hydrothermal method, hydrogen reduction, wet chemical reduction, plasma treatment and heterogeneous ion doping. Finally, the development and challenges of OVs in the field of electrochemical nitrogen fixation are presented. This review shows the important areas of development of catalysts to achieve industrially viable NRR.

The development of catalysts for electrochemical nitrogen reduction toward ammonia: theoretical and experimental advances

Ammonia (NH₃) is essential for the industrial production of fertilizers, pharmaceuticals, plastics, synthetic fibers, resins, and chemicals, and it is also a promising carbon-free energy carrier. The electrocatalytic nitrogen reduction reaction (eNRR) driven by renewable energy sources at ambient temperature and atmospheric pressure is an alternative approach to the Haber-Bosch process for NH₃ synthesis. However, the efficient electrocatalytic reduction of nitrogen (N₂) to NH₃ is challenging due to the lack of effective electrocatalysts. Tremendous effort has been made to develop high-performance electrocatalysts for the eNRR in the past few years. In this review, we summarize recent progress relating to electrocatalysts for the eNRR from both theoretical and experimental aspects. Remaining challenges and perspectives for promoting the eNRR to generate NH₃ are also discussed. This review hopes to guide the design and development of efficient electrocatalysts for the eNRR for NH₃ synthesis.

Sm0.5Sr0.5Co1−xNixO3−δ—A Novel Bifunctional Electrocatalyst for Oxygen Reduction/Evolution Reactions

The development of non-precious metal catalysts with excellent bifunctional activities is significant for air–metal batteries. ABO3-type perovskite oxides can improve their catalytic activity and electronic conductivity by doping transition metal elements at B sites. Here, we develop a novel Sm0.5Sr0.5Co1−xNixO3−δ (SSCN) nanofiber-structured electrocatalyst. In 0.1 M KOH electrolyte solution, Sm0.5Sr0.5Co0.8Ni0.2O3−δ (SSCN82) with the optimal Co: Ni molar ratio exhibits good electrocatalytic activity for OER/ORR, affording a low onset potential of 1.39 V, a slight Tafel slope of 123.8 mV dec−1, and a current density of 6.01 mA cm−2 at 1.8 V, and the ORR reaction process was four-electron reaction pathway. Combining the morphological characteristic of SSCN nanofibers with the synergistic effect of cobalt and nickel with a suitable molar ratio is beneficial to improving the catalytic activity of SSCN perovskite oxides. SSCN82 exhibits good bi-functional catalytic performance and electrochemical double-layer capacitance.

Emerging two-dimensional nanomaterials for electrochemical nitrogen reduction

Ammonia (NH₃) is essential to serve as the biological building blocks for maintaining organism function, and as the indispensable nitrogenous fertilizers for increasing the yield of nutritious crops. The current Haber-Bosch process for industrial NH₃ production is highly energy- and capital-intensive. In light of this, the electroreduction of nitrogen (N₂) into valuable NH₃, as an alternative, offers a sustainable pathway for the Haber-Bosch transition, because it utilizes renewable electricity and operates under ambient conditions. Identifying highly efficient electrocatalysts remains the priority in the electrochemical nitrogen reduction reaction (NRR), marking superior selectivity, activity, and stability. Two-dimensional (2D) nanomaterials with sufficient exposed active sites, high specific surface area, good conductivity, rich surface defects, and easily tunable electronic properties hold great promise for the adsorption and activation of nitrogen towards sustainable NRR. Therefore, this Review focuses on the fundamental principles and the key metrics being pursued in NRR. Based on the fundamental understanding, the recent efforts devoted to engineering protocols for constructing 2D electrocatalysts towards NRR are presented. Then, the state-of-the-art 2D electrocatalysts for N₂ reduction to NH₃ are summarized, aiming at providing a comprehensive overview of the structure-performance relationships of 2D electrocatalysts towards NRR. Finally, we propose the challenges and future outlook in this prospective area.

Tailoring the d-Band Center of Double-Perovskite LaCoxNi1-xO3 Nanorods for High Activity in Artificial N2 Fixation

The d-band center of a catalyst can be applied for the prediction of its catalytic activity, but the application of d-band theory for the electrocatalytic nitrogen reduction reaction (eNRR) has rarely been studied in perovskite materials. In this work, a series of double-perovskite LaCo_xNi_1-xO₃ (LCNO) nanorods (NRs) were synthesized as models, where the d-band centers can be modulated by changing the stoichiometric ratios between Co and Ni elements. Experimentally, the LCNO-III NRs (x = 0.5) attained the highest faradic efficiency and NH₃ yield rate among various LCNO NRs. This result matches well with the finding from theoretical calculations that LCNO-III has the most positive d-band center (ε_d = -0.96 eV vs Fermi level), thus confirming that LCNO-III shows the strongest adsorption ability for N₂ molecules (adsorption energy value of -2.01 eV) for the subsequent N₂ activation and reduction reactions. Therefore, this work proposes a general rule to adopt for developing novel catalysts (especially perovskite-based catalysts) for substantially increasing the eNRR activity by modulating the corresponding d-band centers.

Exploration and Investigation of Periodic Elements for Electrocatalytic Nitrogen Reduction

High demand for green ecosystems has urged the human community to reconsider and revamp the traditional way of synthesis of several compounds. Ammonia (NH₃ ) is one such compound whose applications have been extended from fertilizers to explosives and is still being synthesized using the high energy inhaling Haber-Bosch process. Carbon free electrocatalytic nitrogen reduction reaction (NRR) is considered as a potential replacement for the Haber-Bosch method. However, it has few limitations such as low N₂ adsorption, selectivity (competitive HER reactions), low yield rate etc. Since it is at the early stage, tremendous efforts have been devoted in understanding the reaction mechanism and screening of the electrocatalysts and electrolytes. In this review, the electrocatalysts are classified based on the periodic table with heat maps of Faraday efficiency and yield rate of NH₃ in NRR and their electrocatalytic properties toward NRR are discussed. Also, the activity of each element is discussed and short tables and concise graphs are provided to enable the researchers to understand recent progress on each element. At the end, a perspective is provided on countering the current challenges in NRR. This review may act as handbook for basic NRR understandings, recent progress in NRR, and the design and development of advanced electrocatalysts and systems.

Development and application of ubiquitin-based chemical probes

Protein ubiquitination regulates almost every process in eukaryotic cells. The study of the many enzymes involved in the ubiquitination system and the development of ubiquitination-associated therapeutics are important areas of current research. Synthetic tools such as ubiquitin-based chemical probes have been making an increasing contribution to deciphering various biochemical components involved in ubiquitin conjugation, recruitment, signaling, and deconjugation. In the present minireview, we summarize the progress of ubiquitin-based chemical probes with an emphasis on their various structures and chemical synthesis. We discuss the utility of the ubiquitin-based chemical probes for discovering and profiling ubiquitin-dependent signaling systems, as well as the monitoring and visualization of ubiquitin-related enzymatic machinery. We also show how the probes can serve to elucidate the molecular mechanism of recognition and catalysis. Collectively, the development and application of ubiquitin-based chemical probes emphasizes the importance and utility of chemical protein synthesis in modern chemical biology.

This article reviews the design, synthesis, and application of different classes of Ub-based chemical probes.

2D Electrocatalysts for Converting Earth-Abundant Simple Molecules into Value-Added Commodity Chemicals: Recent Progress and Perspectives

The electrocatalytic conversion of earth-abundant simple molecules into value-added commodity chemicals can transform current chemical production regimes with enormous socioeconomic and environmental benefits. For these applications, 2D electrocatalysts have emerged as a new class of high-performance electrocatalyst with massive forward-looking potential. Recent advances in 2D electrocatalysts are reviewed for emerging applications that utilize naturally existing H₂ O, N₂ , O₂ , Cl^- (seawater) and CH₄ (natural gas) as reactants for nitrogen reduction (N₂ → NH₃ ), two-electron oxygen reduction (O₂ → H₂ O₂ ), chlorine evolution (Cl^- → Cl₂ ), and methane partial oxidation (CH₄ → CH₃ OH) reactions to generate NH₃ , H₂ O₂ , Cl₂ , and CH₃ OH. The unique 2D features and effective approaches that take advantage of such features to create high-performance 2D electrocatalysts are articulated with emphasis. To benefit the readers and expedite future progress, the challenges facing the future development of 2D electrocatalysts for each of the above reactions and the related perspectives are provided.

Enhancing Zn-Ion Storage Capability of Hydrated Vanadium Pentoxide by the Strategic Introduction of La3

Hydrated vanadium pentoxide (VO) cathodes with two-dimensional bilayer structures hold great potential for advanced aqueous Zn-ion batteries (ZIBs) construction, but their further application is impeded by the poor cycling stability. Herein, to address this issue and enhance the Zn ion storage capability, La³⁺ with a big radius was selected to finely tune their nanostructure. The strategic introduction of La³⁺ to VO led to the formation of LaVO₄ , which showed larger interplanar spacing, better electrical conductivity, and superior Zn-ion diffusion efficiency. These unique characteristics were beneficial in the (de)intercalation and the prevention of electrode degradation/collapse, thereby significantly strengthening the corresponding electrochemical performance. As a consequence, the cathode possessed a high specific capacity of 472.5 mAh g^-1 at a current density of 0.38 A g^-1 and displayed good rate performance, accompanied by enduring cycling stability (no decay after 2000 cycles). Besides, when equipped as an aqueous ZIB, it delivered an outstanding peak energy density of 341.9 Wh kg^-1 and a peak power density of 3.22 kW kg^-1 , surpassing most VO-based energy-storage devices.

Efficient Electrocatalytic Nitrogen Fixation on FeMoO4 Nanorods

Electroreduction of N₂ represents a promising technique for ambient NH₃ synthesis, but exploring efficient electrocatalysts for nitrogen reduction reaction (NRR) remains a key challenge. Herein, we reported our experimental and theoretical findings that FeMoO₄ could be a new candidate for effective and durable NRR in neutral solution. The developed FeMoO₄ nanorods exhibited a fascinating NRR activity with an NH₃ yield of 45.8 μg h^-1 mg^-1 (-0.5 V) and a Faradaic efficiency of 13.2% (-0.3 V). Mechanistic studies disclosed that Fe and Mo synergistically promoted the N₂ adsorption and accelerated the electron transfer on FeMoO₄, whereas the unsaturated 3-fold coordinated Mo (Mo_3c) sites served as the main active centers for stabilizing the key *N₂H intermediate and reducing the reaction energy barrier.

Bi nanodendrites for efficient electrocatalytic N2 fixation to NH3 under ambient conditions

Bi nanodendrite acts as an efficient electrocatalyst for ambient N₂-to-NH₃ with NH₃ yield rate of 25.86 μg h⁻¹ mg⁻¹_cat. and faradaic efficiency of 10.8% at −0.60 V and −0.55 V versus RHE, respectively.

Ambient electrochemical NH3 synthesis from N2 and water enabled by ZrO2 nanoparticles

ZrO₂ nanoparticles act as an efficient electrocatalyst for ambient N₂-to-NH₃ fixation. In 0.1 M HCl, it attains a large NH₃ yield rate of 24.74 μg h⁻¹ mg_cat.⁻¹ with a faradaic efficiency of 5.0% at −0.45 V vs. RHE.

Ti3+ self-doped TiO2−x nanowires for efficient electrocatalytic N2 reduction to NH3

Ti³⁺–TiO_2−x/TM behaves as an efficient electrocatalyst for ambient N₂-to-NH₃ fixation with a high faradaic efficiency of 14.62% and a NH₃ yield of 3.51 × 10⁻¹¹ mol s⁻¹ cm⁻² at −0.55 V versus a reversible hydrogen electrode in 0.1 M Na₂SO₄.

P-Doped graphene toward enhanced electrocatalytic N2 reduction

P doping greatly improves electrochemical N₂ reduction over graphene. In 0.5 M LiClO₄, P-doped graphene attains a high Faradic efficiency of 20.82% and a large NH₃ yield of 32.33 μg h⁻¹ mg_cat.⁻¹ at −0.65 V vs. RHE.

Dendritic Cu: a high-efficiency electrocatalyst for N2 fixation to NH3 under ambient conditions

Dendritic Cu behaves as an efficient electrocatalyst for ambient N₂-to-NH₃ fixation with a high Faradaic efficiency of 15.12% and a large NH₃ yield rate of 25.63 μg h⁻¹ mg_cat.⁻¹ at −0.40 V versus reversible hydrogen electrode in 0.1 M HCl.

An Fe2O3 nanoparticle-reduced graphene oxide composite for ambient electrocatalytic N2 reduction to NH3

Fe₂O₃-rGO behaves as an Earth-abundant NRR electrocatalyst for conversion of N₂ to NH₃ in 0.5 M LiClO₄, achieving a large NH₃ yield of 22.13 μg h⁻¹ mg⁻¹_cat and a high faradaic efficiency of 5.89%.