The hydrogen economy is seen as a potential alternative to overcome the depletion of traditional fossil fuels and environmental pollution; therefore, the demand for high-purity hydrogen has rapidly increased. To produce hydrogen in a sustainable and environmentally friendly manner, numerousThe metallic 1T phase of WS 2 (1T-WS 2 ), which boosts the charge transfer between the electron source and active edge sites, can be used as an efficient electrocatalyst for the hydrogen evolution reaction (HER). As the semiconductor 2H phase of WS 2 (2H-WS 2 ) is inherently stable, methods for synthesizing 1T-WS 2 are limited and complicated. Herein, a uniform wafer-scale 1T-WS 2 film is prepared using a plasma-enhanced chemical vapor deposition (PE-CVD) system. The growth temperature is maintained at 150 °C enabling the direct synthesis of 1T-WS 2 films on both rigid dielectric and flexible polymer substrates. Both the crystallinity and number of layers of the as-grown 1T-WS 2 are verified by various spectroscopic and microscopic analyses. A distorted 1T structure with a 2a 0 × a 0 superlattice is observed using scanning transmission electron microscopy. An electrochemical analysis of the 1T-WS 2 film demonstrates its similar catalytic activity and high durability as compared to those of previously reported untreated and planar 1T-WS 2 films synthesized with CVD and hydrothermal methods. The 1T-WS 2 does not transform to stable 2H-WS 2 , even after a 700 h exposure to harsh catalytic conditions and 1000 cycles of HERs. This synthetic strategy can provide a facile method to synthesize uniform 1T-phase 2D materials for electrocatalysis applications.

The octahedral structure of 2D molybdenum disulfide (1T‐MoS2) has attracted attention as a high‐efficiency and low‐cost electrocatalyst for hydrogen production. However, the large‐scale synthesis of 1T‐MoS2 films has not been realized because of higher formation energy compared to that of the trigonal prismatic phase (2H)‐MoS2. In this study, a uniform wafer‐scale synthesis of the metastable 1T‐MoS2 film is performed by sulfidation of the Mo metal layer using a plasma‐enhanced chemical vapor deposition (PE‐CVD) system. Thus, plasma‐containing highly reactive ions and radicals of the sulfurization precursor enable the synthesis of 1T‐MoS2 at 150 °C. Electrochemical analysis of 1T‐MoS2 shows enhanced catalytic activity for the hydrogen evolution reaction (HER) compared to that of previously reported MoS2 electrocatalysts 1T‐MoS2 does not transform into stable 2H‐MoS2 even after 1000 cycles of HER. The proposed low‐temperature synthesis approach may offer a promising solution for the facile production of various metastable‐phase 2D materials.

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The size of the advanced Cu interconnects has been significantly reduced, reaching the current 7.0 nm node technology and below. With the relentless scaling-down of microelectronic devices, the advanced Cu interconnects thus requires an ultrathin and reliable diffusion barrier layer to prevent Cu diffusion into the surrounding dielectric. In this paper, amorphous carbon (a-C) layers of 0.75–2.5 nm thickness have been studied for use as copper diffusion barriers. The barrier performance and thermal stability of the a-C layers were evaluated by annealing Cu/SiO2/Si metal-oxide-semiconductor (MOS) samples with and without an a-C diffusion barrier at 400 °C for 10 h. Microstructure and elemental analysis performed by transmission electron microscopy (TEM) and secondary ion mass spectroscopy showed that no Cu diffusion into the SiO2 layer occurred in the presence of the a-C barrier layer. However, current density-electric field and capacitance–voltage measurements showed that 0.75 and 2.5 nm thick a-C barriers behave differently because of different microstructures being formed in each thickness after annealing. The presence of the 0.75 nm thick a-C barrier layer considerably improved the reliability of the fabricated MOS samples. In contrast, the reliability of MOS samples with a 2.5 nm thick a-C barrier was degraded by sp2 clustering and microstructural change from amorphous phase to nanocrystalline state during annealing. These results were confirmed by Raman spectroscopy, X-ray photoelectron spectroscopy and TEM analysis. This study provides evidence that an 0.75 nm thick a-C layer is a reliable diffusion barrier.

After a gas drainage event causes different degrees of initial porosity in the coal seam, the heterogeneity of the coal mass becomes much more obvious. In this paper, soft coal testing samples with different degrees of heterogeneity were prepared first by a new special experimental research method using hydrogen peroxide in an alkaline medium to generate oxygen. Then, a series of mechanical tests on the soft coal mass samples were carried out under multiple factor coupling conditions of different heterogeneities and confining pressures. The results show that with a low strength, the ductility failure characteristic and a kind of rheology similar to that for soft rock flow were reflected for the soft coal; i.e., the stress-strain curve of the coal mass had no apparent peak strain and residual strength. An interesting phenomenon was found in the test process: there was an upwardly convex critical phase, called the brittle-ductile failure transition critical phase, for the heterogeneous soft coal mass between the initial elastic compression phase and the ductile failure transition phase in the stress-strain curve of the coal mass. An evolution of the brittle-ductile modulus coefficient of the soft coal was developed to analyze the effect of the internal factor (degree of heterogeneity) and external factors (confining pressure) on the transition state of the brittle-ductile failure of soft coal. Further analysis shows that the internal factor (heterogeneity) was also one of the essential factors causing the brittle-ductile transition of soft coal.