Defect engineering is an effective strategy to improve the activity of two-dimensional molybdenum disulfide base planes toward electrocatalytic hydrogen evolution reaction. Here, we report a Frenkel-defected monolayer MoS₂ catalyst, in which a fraction of Mo atoms in MoS₂ spontaneously leave their places in the lattice, creating vacancies and becoming interstitials by lodging in nearby locations. Unique charge distributions are introduced in the MoS₂ surface planes, and those interstitial Mo atoms are more conducive to H adsorption, thus greatly promoting the HER activity of monolayer MoS₂ base planes. At the current density of 10 mA cm⁻², the optimal Frenkel-defected monolayer MoS₂ exhibits a lower overpotential (164 mV) than either pristine monolayer MoS₂ surface plane (358 mV) or Pt-single-atom doped MoS₂ (211 mV). This work provides insights into the structure-property relationship of point-defected MoS₂ and highlights the advantages of Frenkel defects in tuning the catalytic performance of MoS₂ materials.

The addition of certain additives during intercalation and surface modification can result in MXene-based materials with exceptional performances.

MXenes, an emerging two-dimensional (2D) transition metal carbides, nitrides and carbonitrides, have exhibited great potential as electrocatalysts for hydrogen evolution reaction (HER) due to the excellent characters, including excellent structural and chemical stability, superior electrical conductivity, and large active surface area. In this comprehensive study, firstly, the preparation advances of MXenes are systematically summarized. Then, the representative applications of MXenes-based HER electrocatalysts are introduced, from experimental and theoretical aspects. Thirdly, the strategies for improving HER catalytic activity of MXenes are demonstrated, such as optimizing active sites by termination modification and metal-atom doping, increasing active sites by fabricating various nanostructures. Finally, the existing challenges and new opportunities for MXenes-based electrocatalysts are also elucidated. This paper provides reference for the future development of new and efficient MXenes-based electrocatalysts for hydrogen production through water-splitting technology.

Since its invention in the 1960s, one of the most significant evolutions of metal-oxide-semiconductor field effect transistors (MOS-FETs) would be the three dimensionalized version that makes the semiconducting channel vertically wrapped by conformal gate electrodes, also recognized as FinFET. During the past decades, the width of fin (W $${}_{{\rm{fin}}}$$fin ) in FinFETs has shrunk from about 150 nm to a few nanometers. However, W $${}_{{\rm{fin}}}$$fin seems to have been levelling off in recent years, owing to the limitation of lithography precision. Here, we show that by adapting a template-growth method, different types of mono-layered two-dimensional crystals are isolated in a vertical manner. Based on this, FinFETs with one atomic layer fin are obtained, with on/off ratios reaching $$\sim\!\! 10^{7}$$~107 . Our findings push the FinFET to the sub 1 nm fin-width limit, and may shed light on the next generation nanoelectronics for higher integration and lower power consumption.

Two‐dimensional (2D) transition metal dichalcogenides (TMDCs) with unique electrical properties are fascinating materials used for future electronics. However, the strong Fermi level pinning effect at the interface of TMDCs and metal electrodes always leads to high contact resistance, which seriously hinders their application in 2D electronics. One effective way to overcome this is to use metallic TMDCs or transferred metal electrodes as van der Waals (vdW) contacts. Alternatively, using highly conductive doped TMDCs will have a profound impact on the contact engineering of 2D electronics. Here, a novel chemical vapor deposition (CVD) using mixed molten salts is established for vapor–liquid–solid growth of high‐quality rhenium (Re) and vanadium (V) doped TMDC monolayers with high controllability and reproducibility. A tunable semiconductor to metal transition is observed in the Re‐ and V‐doped TMDCs. Electrical conductivity increases up to a factor of 10⁸ in the degenerate V‐doped WS₂ and WSe₂. Using V‐doped WSe₂ as vdW contact, the on‐state current and on/off ratio of WSe₂‐based field‐effect transistors have been substantially improved (from ≈10^–8 to 10^–5 A; ≈10⁴ to 10⁸), compared to metal contacts. Future studies on lateral contacts and interconnects using doped TMDCs will pave the way for 2D integrated circuits and flexible electronics.

2-Inch-wafer-scale MoS₂ films and patterned MoS₂ monolayers were achieved via a vapor-liquid-solid growth using non-volatile precursors.