Atmospheric‐Pressure Synthesis of 2D Nitrogen‐Rich Tungsten Nitride

Abstract

increasing by the abundant WN bond. To the best of our knowledge, the experimental synthesis of 2D nitrogen-rich tungsten nitrides is not reported in literature because of the harsh synthesis condition, stemming from the sluggish reaction thermodynamics of penetrating nitrogen into tungsten lattice. [9] Overall, high pressure and temperature (P-T) synthetic method (5 GPa and 880-2570 K) was adopted to prepare various nitrogen-rich tungsten nitrides such as W 2 N 3 , W 3 N 4 . [10] However, this harsh synthesis condition is laborious to control the morphology of tungsten nitrides, especially for the 2D structure. [11][12][13][14] As an alternative strategy, ammoniating tungsten metals or compounds are extensively studied to produce tungsten nitrides. [9,15] Yet, the reaction is always incomplete, leading to low nitrogen ratio in final products with unreacted tungsten precursor (tungsten, tungsten oxides, etc.). [16] Consequently, developing a facile and real-world synthetic strategy, with favorable reaction thermodynamics and facile morphology control for 2D nitrogen-rich tungsten nitrides, is highly desired but still thought provoking.Herein, we synthesize atomically thin 2D nitrogen-rich hexagonal W 2 N 3 (h-W 2 N 3 ) nanosheets via salt-templated method at atmospheric pressure for the first time. In this strategy, h-W 2 N 3 2D transition metal nitrides, especially nitrogen-rich tungsten nitrides (W x N y , y > x), such as W 3 N 4 and W 2 N 3 , have a great potential for the hydrogen evolution reaction (HER) since the catalytic activity is largely enhanced by the abundant WN bonding. However, the rational synthesis of 2D nitrogen-rich tungsten nitrides is challenging due to the large formation energy of WN bonding. Herein, ultrathin 2D hexagonal-W 2 N 3 (h-W 2 N 3 ) flakes are synthesized at atmospheric pressure via a salt-templated method. The formation energy of h-W 2 N 3 can be dramatically decreased owing to the strong interaction and domain matching epitaxy between KCl and h-W 2 N 3 . 2D h-W 2 N 3 demonstrates an excellent catalytic activity for cathodic HER with an onset potential of −30.8 mV as well as an overpotential of −98.2 mV for 10 mA cm −2 . ElectrocatalysisThe ORCID identification number(s) for the author(s) of this article can be found under https://doi.

Nitrogen Vacancies on 2D Layered W2N3: A Stable and Efficient Active Site for Nitrogen Reduction Reaction

“…Figure d shows the Fourier transform (FT) extended X‐ray adsorption fine structure (EXAFS) spectra of the W 2 N 3 and NV‐W 2 N 3 , which are obtained from normalized W L 3 ‐edge curves (Figure S4, Supporting Information). Both samples show a main coordination peak at 2.8 Å which is assigned to WW bonding . However, the intensity of the peak for NV‐W 2 N 3 at 1.8 Å (WN bonding) becomes weaker compared to that of the pristine W 2 N 3 , indicating the decreased WN bonding number.…”

“…2D material has onefold and fully exposed crystal surface, which is widely used as platform for both theoretical calculations and practical applications in electrocatalysis . In the meantime, many works have shown that 2D materials have surface distortion, which can endow 2D materials and their vacancies with excellent structural stability . Thus, the use of vacancy‐engineered 2D TMNs with single exposed crystal facet and stable vacancy‐site is a feasible way to construct high‐performance NRR catalysts.…”

“…The synthesis of W 2 N 3 usually needs harsh synthetic conditions (5 GPa and 1480 K) due to the large formation energy of WN bonding. Inspired by Zhou and co‐workers who firstly realized the atmospheric‐pressure synthesis of nitrogen‐rich transition metal nitride by domain matching epitaxy, the sodium ion in Na 2 W 4 O 13 can lead to a facile synthesis of W 2 N 3 with lower formation energy . The as‐prepared 2D W 2 N 3 was then annealed under 5% H 2 /Ar at 500 °C for 3 h to generate nitrogen vacancies on W 2 N 3 surface (the sample is denoted as NV‐W 2 N 3 ).…”

A Robust, Freestanding MXene‐Sulfur Conductive Paper for Long‐Lifetime Li–S Batteries

“…These effective LiPSs absorbents include polar metal oxides, such as MnO 2 , TiO 2 , Nb 2 O 5 , etc. Transition metal dichalcoginde (TMDs) are also reported with excellent performance when retarding the LiPSs shuttle . Very recently, Zhou et al reported the synthesis of 2D nitrogen‐rich tungsten nitride through the atmospheric‐pressure method; The formation energy of 2D hexagonal‐W 2 N 3 (h‐W 2 N 3 ) flakes are dramatically decreased owing to the strong interaction and domain matching epitaxy between KCl and h‐W 2 N 3 .…”

Scalable Synthesis of Ultrathin Mn3N2 Exhibiting Room‐Temperature Antiferromagnetism

“…[5] However, the development of ultrathin 2D magnetic materials, potentially important building blocks for spintronics, is still at its initial stage and only a handful of materials have the physics in ultrathin and bulk magnetic materials, and for practical applications. [18,19] This provides a viable route to obtain ultrathin flakes of a TMN with roomtemperature magnetism. This is a common issue in ultrathin 2D or 2D-like TMNs, and because of this, only a few of these materials have been reported, such as Ti 4 N 3 , [16] Mo 2 N, and V 2 N MXene, [17] MoN, [18] and W 2 N. [18] Recently, a high-yield salt-templating method for the synthesis of atomically thin TMNs by ammoniating their metal oxide counterparts was demonstrated.…”