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Ni-based transition metal nitrides (TMNs) have been regarded as promising substitutes for noble-metal electrocatalysts towards the hydrogen evolution reaction (HER) due to their low cost, excellent chemical stability, high electronic conductivity, and unique electronic structure. However, facile green synthesis and rational microstructure design of Ni-based TMNs electrocatalysts with high HER activity remain challenging. In this work, we report the fabrication of Ni/Ni 3 N heterostructure nanoarrays on carbon paper via a one-step magnetron sputtering method under low temperature and N 2 atmosphere. The Ni/Ni 3 N hierarchical nanoarrays exhibit an excellent HER catalytic activity with a low overpotential of 37 mV at 10 mA·cm −2 and robust long-term durability over 100 h. Furthermore, the Ni/Ni 3 N||NiFeOH (NiFeOH = NiFe bimetallic hydroxide) electrolyzer requires a small voltage of 1.54 V to obtain 10 mA·cm −2 for water electrolysis. Density functional theory (DFT) calculations reveal that the heterointerface between Ni and Ni 3 N could directly induce electron redistribution to optimize the electronic structure, which accelerates the dissociation of water molecules and the subsequent hydrogen desorption, and thus boosting the HER kinetics.

Noble-metal-free surface-enhanced Raman scattering (SERS) substrates have attracted great attention for their abundant sources, good signal uniformity, superior biocompatibility, and high chemical stability. However, the lack of controllable synthesis and fabrication of noble-metal-free substrates with high SERS activity impedes their practical applications. Herein, we propose a general strategy to fabricate a series of planar transition-metal nitride (TMN) SERS chips via an ambient temperature sputtering deposition route. For the first time, tungsten nitride (WN) and tantalum nitride (TaN) are used as SERS materials. These planar TMN chips show remarkable Raman enhancement factors (EFs) with ∼ 10 5 owing to efficient photoinduced charge transfer process between TMN chips and probe molecules. Further, structural engineering of these TMN chips is used to improve their SERS activity. Benefiting from the synergistic effect of charge transfer process and electric field enhancement by constructing a nanocavity structure, the Raman EF of WN nanocavity chips could be greatly improved to ∼ 1.29 × 10 7 , which is an order of magnitude higher than that of planar chips. Moreover, we also design the WN/monolayer MoS 2 heterostructure chips. With the increase of surface electron density on the upper WN and more exciton resonance transitions in the heterostructure, a ∼ 1.94 × 10 7 level EF and a 5 × 10 −10 M level detection limit could be achieved. Our results provide important guidance for the structural design of ultrasensitive noble-metal-free SERS chips.

The suitable materials, metal nitrides, are a promising class of electrocatalyst materials for a highly efficient oxygen evolution reaction (OER) because they exhibit superior intrinsic conductivity and have higher sustainability than oxide-based materials. To our knowledge, for the first time, we report a designable synthesis of three-dimensional (3D) and mesoporous Co 3 N@amorphous N-doped carbon (AN-C) nanocubes (NCs) with well-controlled open-framework structures via monodispersed Co 3 [Co(CN) 6 ] 2 Prussian blue analogue (PBA) NC precursors using in situ nitridation and calcination processes. Co 3 N@AN-C NCs (2 h) demonstrate better OER activity with a remarkably low Tafel plot (69.6 mV·dec −1 ), low overpotential of 280 mV at a current density of 10 mA·cm −2 . Additionally, excellent cycling stability in alkaline electrolytes was exhibited without morphological changes and voltage elevations, superior to most reported hierarchical structures of transition-metal nitride particles. The presented strategy for synergy effects of metal-organic frameworks (MOFs)-derived transition-metal nitrides-carbon hybrid nanostructures provides prospects for developing high-performance and advanced electrocatalyst materials.

Tetra metal nitrides (M 4 N; M = Cr, Fe, Co, Mn, Ni) are a promising spintronic material with an anti-perovskite structure and fascinating magnetic characteristics due to a magneto-volume effect. Though a fully stochiometric Mn 4 N or Fe 4 N has been achieved, the lattice parameter (LP) of Co 4 N was always been found to be significantly lower than the anticipated theoretical values, indicating a sub-stochiometric Co 4 N phase. The formation enthalpy of Co 4 N is slightly positive resulting in unfavorable thermodynamical conditions and significant out-diffusion of N from Co 4 N. In this work, we present a comparative study of undoped and Pd-doped Co 4 N thin films synthesized using a reactive nitrogen sputtering. The structural, composition, and magnetic properties have been studied by combining x-ray diffraction, Rutherford backscattering, energy-dispersive x-ray spectroscopy, secondary ion mass spectroscopy, vibrating sample magnetometer, magneto-optical Kerr effect, and polarized neutron reflectivity measurements. It was found that Pd doping of about 5 at.% results in a significant enhancement in the LP of Co 4 N signifying a higher amount of N retention without adversely affecting the growth and magnetic properties. It is further suggested that the amount of Pd doping may further be increased to realize a fully stoichiometric Co 4 N.

Electrochemical nitrogen reduction (NRR) has attracted much attention as a promising technique to produce ammonia at ambient conditions in an environmentally benign and less energy-consuming manner compared to the current Haber–Bosch process. However, even though much research on the NRR catalysts has been conducted, their low selectivity and reaction rate still hinder the practical application of the NRR process. Among various catalysts, transition metal nitride (TMN)-based catalysts are expected to be promising catalysts for NRR. This is because the NRR process can proceed via the unique Mars–Van Krevelen (MvK) mechanism with a compressed competing hydrogen evolution reaction. However, a controversial issue exists regarding the origin of ammonia produced on TMN-based catalysts. The instability of the TMN-based catalysts can lead to ammonia generation from lattice nitrogen instead of supplied N2 gas. Thus, this review summarizes the recent progress of TMN-based catalysts for NRR, encompassing the NRR mechanism, synthetic routes, characterizations, and controversial opinions. Furthermore, future perspectives on producing ammonia electrochemically using TMN-based catalysts are provided.

Nanostructured transition metal nitrides (TMNs) have been considered as a promising substitute for precious metal catalysts toward ORR due to their multi-electron orbitals, metallic properties, and low cost. To design TMN catalysts with high catalytic activity toward ORR, the intrinsic features of the influencing factor on the catalytic activity toward ORR of nanostructured TMNs need to be investigated. In this paper, titanium nitride (TiN), zirconium nitride (ZrN), and hafnium nitride (HfN) nanoparticles (NPs) are highly efficient and synthesized in one step by the direct current arc plasma. TiN, ZrN, and HfN NPs with an oxidation layer are applied as the catalysts of hybrid sodium–air batteries (HSABs). The effect of the composition and structural attributes of TMNs on ORR catalysis is defined as follows: (i) composition effect. With the increase in the oxygen content, the catalytic ORR capability of TMNs decreases progressively due to the reduction in oxygen adsorption capacity; (ii) structure effect. The redistribution of the density of states (DOS) of ZrN indicates higher ORR activity than TiN and HfN. HSABs with ZrN exhibit an excellent cyclic stability up to 137 cycles (about 140 h), an outstanding rate performance, and a specific capacity of 2817 mAh·g−1 at 1.0 mA·cm−2.

The over-dependence on fossil fuels is one of the critical issues to be addressed for combating greenhouse gas emissions. Hydrogen, one of the promising alternatives to fossil fuels, is renewable, carbon-free, and non-polluting gas. The complete utilization of hydrogen in every sector ranging from small to large scale could hugely benefit in mitigating climate change. One of the key aspects of the hydrogen sector is its production via cost-effective and safe ways. Electrolysis and photocatalysis are well-known processes for hydrogen production and their efficiency relies on electrocatalysts, which are generally noble metals. The usage of noble metals as catalysts makes these processes costly and their scarcity is also a limiting factor. Metal nitrides and their porous counterparts have drawn considerable attention from researchers due to their good promise for hydrogen production. Their properties such as active metal centres, nitrogen functionalities, and porous features such as surface area, pore-volume, and tunable pore size could play an important role in electrochemical and photocatalytic hydrogen production. This review focuses on the recent developments in metal nitrides from their synthesis methods point of view. Much attention is given to the emergence of new synthesis techniques, methods, and processes of synthesizing the metal nitride nanostructures. The applications of electrochemical and photocatalytic hydrogen production are summarized. Overall, this review will provide useful information to researchers working in the field of metal nitrides and their application for hydrogen production.

Multiphase sulfur redox reactions with advanced homogeneous and heterogeneous electrochemical processes in lithium–sulfur (Li–S) batteries possess sluggish kinetics. The slow kinetics leads to significant capacity decay during charge/discharge processes. Therefore, electrocatalysts with adequate sulfur‐redox properties are required to accelerate reversible polysulfide conversion in cathodes. In this study, we have fabricated an oxygen‐modulated metal nitride cluster (C‐MoNx‐O) that has a moderate binding ability to the insoluble Li2Sx for reversible polysulfide electrocatalysis. A Li–S battery equipped with C‐MoNx‐O electrocatalyst displayed a high discharge capacity of 875 mAh g−1 at 0.5 C. The capacity decay rate of each cycle was only 0.10% after 280 cycles, which is much lower than the control groups (C‐MoOx: 0.16%; C‐MoNx: 0.21%). Kinetic studies and theoretical calculations suggest that C‐MoNx‐O electrocatalyst presents a moderate binding ability to the insoluble Li2S2 and Li2S when compared to the C‐MoOx and C‐MoNx surfaces. Thus, the C‐MoNx‐O can effectively immobilize and reversibly catalyze the solid–solid conversion of Li2S2–Li2S during charge–discharge cycling, thus promoting reaction kinetics and eliminating the shuttle effect. This study to design oxygen‐doped metal nitrides provides innovative structures and reversible solid–solid conversions to overcome the sluggish redox chemistry of polysulfides. An oxygen‐modulated metal nitride cluster (C‐MoNx‐O) for moderate binding and reversible catalysis of Li2Sx has been synthesized to achieve the fast conversion of polysulfides. Both the kinetic studies and theoretical calculation suggest that the C‐MoNx‐O can effectively immobilize and reversibly catalyze the polysulfide intermediates during cycling, thus promoting the reaction kinetics and eliminating the shuttle effects in Li–S batteries.

Transition metal nitrides (TMNs) are considered as viable alternatives to noble metal catalysts owing to their versatile electronic structure and favorable catalytic performance. However, the conventional synthetic processes for TMNs suffer from high energy consumption and low production yield. In this study, a range of TMNs and their hetero-composite arrays were successfully synthesized via an ultrafast flash Joule heating technology within 0.5 s. As a proof concept, the nitrides and hetero-composites were applied for the electrocatalytic hydrazine oxidation reaction (HzOR), in which the Co 4 N/Mo 16 N 7 arrays shows the best performance with a geometric current density of 100 mA cm −2 at 23 mV ( vs . reversible hydrogen electrode (RHE)). This work paves a new way for the ultrafast synthesis of TMNs which could meet the ever-increased energy crisis.

The current economic and ecological situation encourages the use of steel to push the technological limits and offer more cost-effective products. The enhancement of steel properties like wear, corrosion, and oxidation resistance is achieved by the addition of small amounts of chemical elements such as Cr, Ni, Si, N, etc. The steel surface can be protected by different treatments such as heating and coating, among others. For many decades, coatings have been an effective solution to protect materials using thin hard films. Several technologies for thin film deposition have been developed. However, some of them are restricted to certain fields because of their complex operating conditions. In addition, some deposition techniques cannot be applied to a large substrate surface type. The magnetron sputtering deposition process is a good option to overcome these challenges and can be used with different substrates of varying sizes with specific growth modes and for a wide range of applications. In this review article, we present the sputtering mechanism and film growth modes and focus on the mechanical and tribological behavior of nitride thin films deposited by the magnetron sputtering technique as a function of process conditions, particularly bias voltage and nitrogen percentage. The biomedical properties of transition metal nitride coatings are also presented.