Ultra-thin III–V semiconductors, which exhibit intriguing characteristics, such as two-dimensional (2D) electron gas, enhanced electron–hole interaction strength, and strongly polarized light emission, have always been anticipated in future electronics. However, their inherent strong covalent bonding in three dimensions hinders the layer-by-layer exfoliation, and even worse, impedes the 2D anisotropic growth. The synthesis of desirable ultra-thin III–V semiconductors is hence still in its infancy. Here we report the growth of a majority of ultra-thin III–V single crystals, ranging from ultra-narrow to wide bandgap semiconductors, through enhancing the interfacial interaction between the III–V crystals and the growth substrates to proceed the 2D layer-by-layer growth mode. The resultant ultra-thin single crystals exhibit fascinating properties of phonon frequency variation, bandgap shift, and giant second harmonic generation. Our strategy can provide an inspiration for synthesizing unexpected ultra-thin non-layered systems and also drive exploration of III–V semiconductor-based electronics.

Aqueous zinc (Zn)‐ion batteries (ZIBs) have been considered as the most promising candidate for large‐scale energy storage system. However, the severe and uncontrollable dendrite growth of Zn anodes hinders the practical application. Herein, an ultraconformal horizontal Zn deposition is achieved, which is profiting from the epitaxial interface (InGaZn6O9) formed via spontaneously alloying between liquid Ga–In alloy (EGaIn) and Zn. The exposed (0016) plane of InGaZn6O9 matches well with (002) plane of Zn, inducing horizontal and dense Zn deposition. The resultant anode endows with prolonged cycling stability, and the full battery paired with MnO2 exhibits a stable lifespan over 4400 cycles at 5 A g−1. Meanwhile, the self‐formed ultraconformal interface realizes 360° no dead angle protection of anode, which is promising in flexible electronics. And there is no obvious capacity recession of the pouch cell even after bending 180°, demonstrating impressive flexibility. More importantly, the interface can be simply fabricated over a large area, displaying the large‐scale viability. The tailored approach delivers a constructive guideline for dendrite‐free Zn anode, showing great potential in the industrial production.

Germanium, the prime applied semiconductor, is widely used in solid‐state electronics and photoelectronics. Unfortunately, since the 3D diamond‐like structure with strong covalent bonds impedes the 2D anisotropic growth, only the examples of ultrathin Ge along the (111) plane have been investigated, much less to the controllable synthesis along another crystal surface. Meanwhile, Ge(111) flakes are limited in semiconductor applications because of their gapless property. Here, ultrathin Ge(110) single crystal is synthesized with semiconductive property via gallium‐associated self‐limiting growth. The obtained ultrathin Ge(110) single crystal exhibits anisotropic honeycomb structure, uniformly incremental lattice, wide tunable direct‐bandgap, blue‐shifted photoluminescence emission, and unique phonon modes, which are consistent with the previous theoretical predictions. It also confirms excellent second harmonic generation and high hole mobility of 724 cm2 V−1 s−1. The realization of ultrathin Ge(110) single crystal will provide an excellent candidate for application in electronics and optoelectronics.

sources into fuels and value-added chemicals. [1−3] However, non-ideal catalytic activity primarily caused by the sluggish kinetics has long posed a crucial challenge in restricting the efficiency of electrocatalytic reactions. [4,5] Based on this, enormous research is devoted to enhancing the intrinsic activity of pre-existing active sites. For example, facet control can selectively expose the high-energy facets of catalysts to promote the adsorption of electrolytes, providing higher catalytic performance. [6] However, catalysts with high-energy facets are generally thermodynamic unstable and their preparations remain greatly challenging. Strain regulation can adjust the local coordination environment of active sites, [7] but its application is restricted by the stability of the modified structure with huge strain. Additionally, alloying with metals/nonmetals is also an effective strategy to decrease the reaction barrier for electrocatalytic reactions, [8] while the thermodynamic miscibility among the different elements is a necessary prerequisite. [9] In essence, the reaction kinetics is effectively triggered to promote the catalytic performance by these design approaches, which is ascribed to appropriate electronic structures. [10,11] Nevertheless, as for the existing catalytic materials, a rational design to tailor the optimal electronic structures is currently lacking, which is highly desired.Here, we propose a design principle, namely "dual self-built gating" to greatly boost the hydrogen evolution reaction (HER) performance of catalysts. Taking ReS 2 and WS 2 as an example, the dual self-built gating originated from in-plane ReS 2 -WS 2 covalent bonds and out-plane ReS 2 /WS 2 interlayer interaction induces electrons to directionally transfer from WS 2 to ReS 2 , [12,13] resulting in charge redistribution at the interface. In this case, owing to the tailored electronic structures, dual selfbuilt gating can balance the adsorption of intermediates and the desorption of hydrogen synergistically, leading to a dramatic improvement in reaction kinetics. As demonstrated by density functional theory (DFT) calculations, the dual gating region shows a Gibbs free energy close to zero (0.03 eV), suggesting that the charge redistribution at the interface enhances the intrinsic activity of active sites. More interestingly, on account of the adjustable carrier density, we also confirm the Optimizing the intrinsic activity of active sites is an appealing strategy for accelerating the kinetics of the catalytic process. Here, a design principle, namely "dual self-built gating", is proposed to tailor the electronic structures of catalysts. Catalytic improvement is confirmed in a model catalyst with a ReS 2 -WS 2 /WS 2 hybridized heterostructure. As demonstrated in experimental and theoretical results, the dual gating can bidirectionally guide electron transfer and redistribute at the interface, endowing the model catalyst with an electron-rich region. The tailored electronic structures balance the adsorption of intermediate...

Two-dimensional (2D) transition-metal borides (TMBs) are especially expected to exhibit excellent performance in various fields among electricity, superconductivity, magnetism, mechanics, biotechnology, battery, and catalysis. However, the synthesis of ultrathin TMB single crystals with ultrahigh phase purity was deemed extremely challenging and has not been realized till date. That is because TMBs have the most kinds of crystal structures among inorganic compounds, which possess generous phase structures with similar formation energies compared with other transition-metal compounds, attributing to the metalloid and electron-deficient characteristics of boron. Herein, for the first time, we demonstrate a chemical potential-modulated strategy to realize the precise synthesis of various ultrahigh-phase-purity (approximately 100%) ultrathin TMB single crystals, and the precision in the phase formation energy can reach as low as 0.01 eV per atom. The ultrathin MoB2 single crystals exhibit an ultrahigh Young’s modulus of 517 GPa compared to other 2D materials. Our work establishes a chemical potential-modulated strategy to synthesize ultrathin single crystals with ultrahigh phase purity, especially those with similar formation energies, and undoubtedly provides excellent platforms for their extensive research and applications.