Atomic layer deposited tungsten nitride thin films as a new lithium-ion battery anode

Abstract

This article demonstrates the atomic layer deposition (ALD) of tungsten nitride using tungsten hexacarbonyl [W(CO)6] and ammonia [NH3] and its use as a lithium-ion battery anode. In situ quartz crystal microbalance (QCM), ellipsometry and X-ray reflectivity (XRR) measurements are carried out to confirm the self-limiting behaviour of the deposition. A saturated growth rate of ca. 0.35 Å per ALD cycle is found within a narrow temperature window of 180-195 °C. In situ Fourier transform infrared (FTIR) vibrational spectroscopy is used to determine the reaction pathways of the surface bound species after each ALD half cycle. The elemental presence and chemical composition is determined by XPS. The as-deposited material is found to be amorphous and crystallized to h-W2N upon annealing at an elevated temperature under an ammonia atmosphere. The as-deposited materials are found to be n-type, conducting with an average carrier concentration of ca. 10(20) at room temperature. Electrochemical studies of the as-deposited films open up the possibility of this material to be used as an anode material in Li-ion batteries. The incorporation of MWCNTs as a scaffold layer further enhances the electrochemical storage capacity of the ALD grown tungsten nitride (WNx). Ex situ XRD analysis confirms the conversion based reaction mechanism of the as-grown material with Li under operation.

Self-standing Ni-WN heterostructure nanowires array: A highly efficient catalytic cathode for hydrogen evolution reaction in alkaline solution

“…The binding energy of N 1 s at 397.5 eV is consistent with W-N bond [25]. The N 1 s peak at 400.9 eV can be attributed to the atoms or molecules appearing at the interstitial positions of WN/ CC [24,26]. All these results strongly suggest that WN nanowires array was successfully grown on CC substrate.…”

“…S2 presents the high-resolution X-ray photoelectron spectroscopy (XPS) spectra in W and N 1 s regions for WN/CC. The peaks at 33.0 and 35.5 eV represent the binding energies of W 4f [24,25]. The binding energy of N 1 s at 397.5 eV is consistent with W-N bond [25].…”

“…Fig. 2e shows a lattice fringe with the interfringe distance of 0.204 nm corresponding to the (111) plane of Ni phase [24]. The interfringe distance of 0.206 nm corresponds to the (200) plane of WN phase (Fig.…”

Twinned Tungsten Carbonitride Nanocrystals Boost Hydrogen Evolution Activity and Stability

“…Its W 4f X‐ray photoelectron spectroscopy spectrum (Figure f) is featured with two pronounced peaks centered at 31.8 and 33.9 eV, typical to tungsten carbonitrides in general . Peaks at the higher binding energy of 35.7 and 37.9 eV are resulted from the inevitable surface oxidation of the twinned WCN upon exposure to air . For comparison, the XPS analysis of W 2 C is shown in Figure S9 in the Supporting Information.…”

Mesoporous WN/WO3-Composite Nanosheets for the Chemiresistive Detection of NO2 at Room Temperature

“…The following can be considered as a plausible explanation based on our experimental results. Firstly, WN exhibits metallic properties with a high electron concentration of about (5-6)ˆ10 20 cm´3 and a resistivity of (1-2)ˆ10´1 Ω at room temperature [38]. However, WO 3 is an n-type semiconductor, whose resistivity is far larger than that of WN.…”