Two-dimensional (2D) materials have attracted tremendous research interest since the breakthrough of graphene. Their unique optical, electronic, and mechanical properties hold great potential for harnessing them as key components in novel applications for electronics and optoelectronics. Their atomic thickness and exposed huge surface even make them highly designable and manipulable, leading to the extensive application potentials. What's more, after acquiring the qualification for being the candidate for next-generation devices, the assembly of 2D materials monomers into mass or ordered structure is also of great importance, which will determine their ultimate industrialization. By designing the monomers and regulating their assembling behavior, the exploration of 2D materials toward the next-generation circuits can be spectacularly achieved. In this review, we will first overview the emerging 2D materials and then offer a clear guideline of varied physical and chemical strategies for tuning their properties. Furthermore, assembly strategies of 2D materials will also be included. Finally, challenges and outlooks in this promising field are featured on the basis of its current progress.

Various strategies for improving the catalytic performance of two dimensional nanomaterials for HER.

A number of non‐noble catalysts are developed for hydrogen production via acidic water electrolysis. Nevertheless, for the more economical alkaline hydrogen generation, the restricted kinetics of the water dissociation Volmer step along with its following proton recombination Tafel step for these non‐noble electrocatalysts generally lead to sluggish hydrogen‐production process. Here, a facile method is designed to nest nanometric Ni5P4 clusters on NiCo2O4 (achieving Ni5P4@NiCo2O4) by a phosphating process of NiO clusters on NiCo2O4. Acting as a high‐efficiency electrode for alkaline water electrolysis, the Ni5P4@NiCo2O4 can efficiently and preferentially convert H2O to H2 with a low overpotential of 27  mV at 10 mA cm−2 and the Tafel slope of 27  mV dec−1, which are comparable to the results for platinum and superior than those of the state‐of‐the‐art platinum‐free electrocatalysts. Density functional theory calculations confirm that NiCo2O4 species exhibit a higher ability to electrolyze water into H* intermediate and then Ni5P4 clusters facilitate the subsequent desorption of the H2 products. Profiting from the promoted kinetic steps, the Ni5P4@NiCo2O4 electrocatalyst is promising for scalable alkaline hydrogen production.

Ultrathin oxides have been reported to possess excellent properties in electronic, magnetic, optical, and catalytic fields. However, the current and primary approaches toward the preparation of ultrathin oxides are only applicable to amorphous or polycrystalline oxide nanosheets or films. Here, we successfully synthesize high-quality ultrathin antimony oxide single crystals via a substrate-buffer-controlled chemical vapor deposition strategy. The asobtained ultrathin antimony oxide single crystals exhibit high dielectric constant (~100) and large breakdown voltage (~5.7 GV m −1). Such a strategy can also be utilized to fabricate other ultrathin oxides, opening up an avenue in broadening the applicaitons of ultrathin oxides in many emerging fields.

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