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In this study, the synthesis, followed by a detailed evaluation of the structural, optical, and electrical properties of the N‐ZnO/N‐rGO nanocomposite prepared using a one‐step low‐temperature hydrothermal process, is reported. By employing N, N‐dimethylformamide (DMF) as the reducing agent and urea as the nitrogen precursor, simultaneous reduction and nitrogen doping are achieved in the nanocomposite. X‐ray diffraction (XRD), X‐ray photoelectron spectroscopy (XPS), and Raman measurements are used for the structural evaluation. The formation of composites is verified using the ZnC/ZnOC bonds in the XPS. The nitrogen doping in the nanocomposites varies from 0.8% to 1.8%. The major nitrogen moieties observed here include pyrrolic N, pyridinic N, and graphitic N. The electrical response is measured using current–voltage characteristics, and enhanced conductivity was observed in the sample with the highest percentage of pyrrolic N. This is attributed to the superior electron transport mechanism of pyrrolic N in the graphene structure. The current response is found to increase from 2 to 10 μA from ZnO/rGO to N‐ZnO/N‐rGO nanocomposite. The integration of N‐rGO support with extensively doped pyrrolic end groups for the N‐ZnO nanoparticles has been found to improve the conduction mechanism and is hence promising for many applications. [ABSTRACT FROM AUTHOR]

Layered MoS2 and WS2 semiconductors are well-known electrocatalysts for hydrogen generation by electrochemical water splitting. However, their hydrogen evolution reaction (HER) activity is significantly affected in neutral and alkaline environments due to sluggish kinetics and a slow charge transfer rate. Here, we report the improved electrochemical activity of Ir-doped degenerate WS2 semiconductors under different electrolytic conditions covering a wide pH range. It was found that the pristine WS2 (n-WS2) transforms into p-type semiconductors after Ir-doping, among which the sample with Ir 9.8 at% shows a degenerate (p+-WS2-9.8) semiconductor nature with high hole density. The p+-WS2-9.8 catalyst exhibits superior HER activity with a low overpotential (η10 = 92, 248, and 548 mV vs. RHE) and low Tafel slope (b = 33, 49, and 89 mV dec−1) in 0.5 M H2SO4, 1 M KOH, and 1 M Na2SO4 electrolytes, respectively. The hole-degenerate doping-induced enhancement of electrical conductivity enables efficient HER activity of the doped semiconductor catalyst. This work demonstrates that degenerate doping is a potential research strategy for the design and development of 2D semiconductor-based efficient catalysts. [ABSTRACT FROM AUTHOR]

It is well known that the electrochemical energy generation and storage performance of two-dimensional layered transition metal dichalcogenides (for example, MoS2 and WS2) strongly depend on the phase and properties of the electrode material. In this work, we report that 2H/1T phase coupling induced by Ru doping leads to improved electrochemical symmetric supercapacitor and hydrogen evolution reaction (HER) performance of a WS2 nanosheet electrode. XRD and Raman studies indicate that a 2H/1T multiphase emerges in WS2 nanosheets for the sample with 10 at% Ru (2H/1T-WS2-10) and other samples retain the parent 2H phase at a low Ru doping level. The 2H/1T-WS2-10 electrode with excellent catalytic activity delivers a 113 mV overpotential at a 10 mA cm−2 current density in 0.5 M H2SO4 electrolyte. Furthermore, the same electrode exhibits superior symmetric supercapacitor performance with high specific capacitance (664 F g−1@1 A g−1) and energy density (92 W h kg−1@1 A g−1) in 1 M Na2SO4 electrolyte. This work opens the way for the multifunctional use of doped WS2 for electrochemical energy conversion and storage applications. [ABSTRACT FROM AUTHOR]

The preparation of 1D WS(2) and MoS(2) flexible nanoribbons by laser-induced unzipping of the nanotubes is reported. The nanoribbons are of high quality, uniform width, and devoid of surface contamination. The zig-zag edges in WS(2) nanoribbons give rise to ferromagnetism at room temperature., (© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)