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The sp²-hybridization is key to understand structures of 2D materials with light p-block elements. However, hunting for sp²-hybridized 2D materials with heavy p-block elements remains challenging due to weaker π-bonding and increased steric effects. Here we proposed design principles for 2D materials based on carbon nitride with adjacent Lewis-acidic center of group IIIA elements. We introduce a family of 2D materials XB₉C₄N₆ (X = Al, Ga, In and Tl) with high thermodynamic stability. Density functional theory (DFT) calculations reveal that XB₉C₄N₆ exhibit a polycyclic lattice with high delocalized π electrons, primarily from B₆ ring, which play the key role in the hole and electron transports. These materials exhibit small electron effective mass of ∼ 0.28 m₀, suitable bandgaps of ∼ 1.2 eV and strong light absorption peaks of violet, red and near-infrared lights, which cover the solar spectral irradiance. Notably, AlB₉C₄N₆ emerges as an environmentally friendly semiconductor for electronics and photovoltaic devices. The design principles will enrich the fundamental understanding of π-conjugated heavy p-block elements and family of sp²-hybridized 2D materials.

Graphene exhibits promise in gas detection applications despite its limited selectivity. Functionalization with fluorine atoms offers a potential solution to enhance selectivity, particularly towards ammonia (NH+) molecules. This article presents a study on electron-beam fluorinated graphene (FG) and its integration into gas sensor platforms. We begin by characterizing the thermal stability of fluorographene, demonstrating its resilience up to 450 °C. Subsequently, we investigate the nature of NH₃ interaction with FG, exploring distinct adsorption energies to address preferential adsorption concerns. Notably, we introduce an innovative approach utilizing x-ray photoelectron spectroscopy cartography for simultaneous analysis of fluorinated and pristine graphene, offering enhanced insights into their properties and interactions. This study contributes to advancing the understanding and application of FG in gas sensing technologies.

Herein, the energy dispersion relationship and the density of states of triangular and rectangular moiré patterns are investigated using a tight binding model. Their characteristics of Hofstadter butterflies under different magnetic fields are also examined. The results indicate that, by analyzing different moiré superlattices, Hofstadter butterflies arising from different moiré pattern structures are obtained, exhibiting considerable fractal characteristics and self-similarities. Moreover, it is also observed that under an alternating magnetic field, the redistribution of electronic states leads to a significant change in the density of states curve, and the Van Hove peak changes with the increase in magnetic field intensity. This study enriches the understanding of the electronic behavior of moiré systems, but it also provides multiple potential application directions for future technological development.

Transition metal dichalcogenides (TMDCs) hold significant promise in constructing next-generation high-performance electronic devices, potentially extending Moore's law and enabling the realization of three-dimensional integrated circuit architectures. However, realizing this potential depends critically on developing a reliable method to transfer TMDCs from a growth substrate to desirable surfaces. Here, we report a dry-transfer strategy of liquid nitrogen-assisted cryogenic exfoliation to achieve large-scale and superclean transfer of TMDCs. Benefited from the synergistic effect of liquid nitrogen-induced exfoliation and protection of hafnium oxide, the transferred TMDCs are free from polymer residues and show excellent electrical property, and taking n-type single-crystal molybdenum disulfide as a demonstration, the transferred TMDC exhibits high carrier mobility up to 38.4 cm2 V-1 s-1. Moreover, this transfer method shows versatile capabilities in transferring monolayer and multilayer TMDCs and constructing bi- and trilayer heterostructures. Therefore, our proposed transfer methodology promises the integration of TMDCs into future, ultimately scaled-down, electronic device technologies.

Self-powered photodetectors, operating without an external power source, have garnered extensive interest for infrared (IR) detection owing to their vast potential in low-power consumption sensor systems. Here, a short-wavelength infrared (SWIR) heterojunction photodetector utilizing semiconducting graphene nanoribbons has been achieved and demonstrated record-high performance. In the self-powered mode, the heterojunction photodetector presents a responsivity of 73.5 A/W and a detectivity of 7.5 × 10¹⁴ Jones, surpassing previously reported self-powered IR photodetectors by several orders of magnitude. The superior performance is primarily due to the enhancement of the electric field caused by the photogating effect at the heterointerface. The device also displays unparalleled performance at −5 V bias voltage, achieving a responsivity of 843 A/W, a detectivity of 10¹⁵ Jones, and an external quantum efficiency of 10⁵%, all of which are record-breaking values for SWIR photodetectors to date. Therefore, our approach provides new insight and demonstrates great potential for future high-performance low-power consumption IR detection technology.

Graphene films (GFs) exhibit exceptional thermal conductivity, making them highly promising for thermal management applications by efficiently dissipating heat and ensuring the stable operation of electronic devices. However, their widespread adoption is hindered by complex preparation processes, particularly due to the ultrahigh temperature annealing treatments. To address this challenge, this work presents an energy-saving and simple-to-operate preparation strategy of GFs. The fabrication process involves the synchronous reduction and assembly of graphene oxide (GO) on metal substrates, followed by a two-step treatment consisting of 1000°C annealing treatment and laser-irradiation treatment to remove the oxygen-containing functional groups and repair the structural defects in the film. By substituting traditional ultra-high temperature treatment with laser irradiation, this approach significantly reduces the energy consumption and fabrication time, and the resulting GFs, after mechanical pressing, achieve an in-plane thermal conductivity of 1801.07 Wm^-1K^-1, surpassing that of conventional metal such as copper and aluminum. Therefore, our approach provides a superior thermal management solution for next-generation high-power electronics.

Recently, Stone-Wales (SW) defects gradually attracted people's research interest because of their unique properties. The theoretical research indicated that the SW defect in hexagonal boron nitride (h-BN) can lead to new defect levels in bandgap, making h-BN apply in ultraviolet emitters. However, the SW defect is always observed in graphene and rarely observed in h-BN in the experiments. Here, we confirmed the SW defects are not easily formed in h-BN under thermodynamic conditions by first-principles calculations. Specifically, the monolayer h-BN with SW defect (h-BN-SW) has the weak bond strength, dynamic stability and high-temperature thermal stability, facilitating the healing of SW defects under high-temperature conditions and the role of hydrogen. Additionally, we found the SW defect in AB stacked h-BN (AB-h-BN) have good mechanical stability, dynamic stability and thermodynamic stability than h-BN-SW, especially for AB-h-BN-2SW (2SW defects formed in upper and lower layer of AB-h-BN, respectively), which can meet the requirements for its application in electronic devices. Even under thermodynamic conditions, the formation of SW defects is extremely challenging. Electron beam irradiation technology provides a window for the generation of SW defects in h-BN. This offers opportunities for the introduction and control of SW defects, while also creating potential for their application in electronic devices. Moreover, we found that the absorption peak broadens, and a new absorption peak appears with the generation of SW defects, which is mainly induced by the decrease of bandgap and the generation of defect levels. Our research can provide theoretical guidance at atomic scale for designing and applying h-BN with SW defect in the experiments.

Ultrafast high-temperature sintering (UHS) is a novel sintering technique with ultrashort firing cycles (e.g., a few tens of seconds). The feasibility of UHS has been validated on several ceramics and metals; however, its potential in consolidating glass-ceramics has not yet been demonstrated. In this work, an optimized carbon-free UHS was utilized to prepare ZrO2-SiO2 nanocrystalline glass-ceramics (NCGCs). The phase composition, grain size, densification behavior, and microstructures of NCGCs prepared by UHS were investigated and compared with those of samples sintered by pressureless sintering. Results showed that NCGCs with a high relative density (similar to 95%) can be obtained within similar to 50 s discharge time by UHS. The UHS processing not only hindered the formation of ZrSiO4 and cristobalite but also enhanced the stabilization of t-ZrO2. Meanwhile, owing to the ultrashort firing cycles, the UHS technology allowed the NCGCs to be consolidated in a far from equilibrium state. The NCGCs showed a microstructure of spherical monocrystalline ZrO2 nanocrystallites embedded in an amorphous SiO2 matrix.

The past one and half decades have witnessed a tremendous development of graphene electronics, and the key to the success of graphene is its exceptional properties. The lacking of an inherent bandgap endows graphene with excellent electrical properties but considerably limits its applications in light-emitting and high-performance graphene-based devices. Herein, an approach for the direct writing of semiconducting and photoluminescent fluorinated graphene (C4F) patterns on monolayer graphene by an optimized electron-beam-activated fluorination technique is reported. A series of characterization approaches, such as atomic force microscopy, X-ray photoelectron spectroscopy and Raman spectroscopy were used to demonstrate the successful preparation of C4F for maskless lithography. Specially, a sharp and strong photoluminescence located at the purple light range of ∼380 nm was observed in C4F, demonstrating a desirable semiconducting nature, and the bandgap was further confirmed by follow-up electrical measurements, where the C4F filed-effect transistor exhibited a p-type semiconductor behavior and significantly enhanced on/off ratio. Therefore, this work provides a novel technique for the fabrication of graphene devices for promising electronic and optoelectronic applications, but also opens a route towards the tailoring and engineering of electronic properties of graphene.

In this work, an aerodynamic levitation technology (ALT) was utilized to prepare ZrO2-SiO2 glass-ceramics with two different ZrO2 contents, that is, 35 mol% and 50 mol%. The glass-ceramics were partially melted at similar to 2000 degrees C or fully melted at similar to 3000 degrees C by ALT, followed by rapid quenching to obtain spherical glass-ceramic beads. The phase compositions and microstructures of the glass-ceramics were characterized. Crystallization of ZrO2 occurred during the solidification process and ZrO2 content, processing temperature, and the addition of yttrium (3 mol%) affected the crystalline phase of ZrO2. No ZrSiO4 or crystalline SiO2 were formed during the solidification process and the glass-ceramics were away from thermodynamic equilibrium due to rapid quenching. The glass-ceramics showed a microstructure of irregular-shaped ZrO2 micro-aggregates embedded in an amorphous SiO2 matrix, with lamellar twins and lattice defects formed within ZrO2 crystals. For samples prepared at similar to 3000 degrees C, a liquid-liquid phase separation occurred in the melt, which eventually resulted in the formation of large and irregular-shaped ZrO2 aggregates. In comparison, for samples prepared at similar to 2000 degrees C, pre-existed ZrO2 crystals formed during heating acted as nucleation sites during the cooling process, followed by grain growth to form large ZrO2 aggregates. Solidification and microstructure formation mechanisms were proposed to elucidate the solidification process during rapid cooling and the microstructure of the glass-ceramics obtained.