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Hydrovoltaic energy technology that generates electricity directly from the interaction of materials with water has been regarded as a promising renewable energy harvesting method. With the advantages of high specific surface area, good conductivity, and easily tunable porous nanochannels, two‐dimensional (2D) nanomaterials have promising potential in high‐performance hydrovoltaic electricity generation applications. Herein, this review summarizes the most recent advances of 2D materials for hydrovoltaic electricity generation, including carbon nanosheets, layered double hydroxide (LDH), and layered transition metal oxides and sulfides. Some strategies were introduced to improve the energy conversion efficiency and the output power of hydrovoltaic electricity generation devices based on 2D materials. The applications of these devices in self‐powered electronics, sensors, and low‐consumption devices are also discussed. Finally, the challenges and perspectives on this emerging technology are outlined. Hydrovoltaic energy technology that generates electricity directly from the interaction of materials with water has been regarded as a promising renewable energy harvesting method. This review summarizes the most recent advances of 2D materials for hydrovoltaic electricity generation, including carbon nanosheets, layered double hydroxide, and layered transition metal oxides and sulfides. Perspectives toward the future applications of 2D materials in hydrovoltaic electricity generation are also outlined.

Chemical vapor deposition (CVD) approach offers a controllable strategy for preparing large‐area and high‐quality few‐layer (mainly bilayer or trilayer) twisted or untwisted two‐dimensional (2D) materials, and is predicted to boost the development of 2D materials from laboratory research to industrial applications. Chemical vapor deposition approach offers a controllable strategy for preparing large‐area and high‐quality few‐layer (mainly bilayer or trilayer) twisted or untwisted two‐dimensional (2D) materials, and is predicted to boost the development of 2D materials from laboratory research to industrial applications.

Retaining the ultrathin structure of two‐dimensional materials is very important for stabilizing their catalytic performances. However, aggregation and restacking are unavoidable, to some extent, due to the van der Waals interlayer interaction of two‐dimensional materials. Here, we address this challenge by preparing an origami accordion structure of ultrathin two‐dimensional graphitized carbon nitride (oa‐C3N4) with rich vacancies. This novel structured oa‐C3N4 shows exceptional photocatalytic activity for the CO2 reduction reaction, which is 8.1 times that of the pristine C3N4. The unique structure not only prevents restacking but also increases light harvesting and the density of vacancy defects, which leads to modification of the electronic structure, regulation of the CO2 adsorption energy, and a decrease in the energy barrier of the carbon dioxide to carboxylic acid intermediate reaction. This study provides a new avenue for the development of stable high‐performance two‐dimensional catalytic materials. We develop a three‐dimensional origami accordion‐like structure of graphitized carbon nitride (oa‐C3N4) that completely prevents restacking, where the existence of N vacancies promotes efficient surface adsorption of CO2 molecules and lowers the energy barrier of the CO2 → *COOH reaction. The as‐required origami accordion‐like oa‐C3N4 achieves remarkable photocatalytic activity and selectivity for the CO2 reduction to CO reaction.

Two‐dimensional (2D) materials with free of dangling bonds have the potential to serve as ideal channel materials for the next generation of field‐effect transistors (FETs) due to their atomic‐thin and excellent electronic properties. However, the performance of 2D materials‐based FETs is still dictated by the interface between electrodes/dielectrics and 2D materials. Several technical challenges such as improving device stability, reducing contact resistance, and advancing mobility need to be overcome. Herein, we focus on the effects of atomic‐scale interface engineering on the contact resistance and dielectric layer for 2D FETs. Universal strategies we consider to achieve ohmic contact and develop high‐quality, defect‐free dielectric layers are provided. Furthermore, advancing the performance of 2D materials‐based FETs and binding to silicon substrates are briefly analyzed. Atomic‐scale interface engineering in 2D materials‐based field‐effect transistors (FETs) for ohmic contacts and high‐κ dielectric layer are reviewed. Treatments and electrode fabrication methods are introduced for ohmic contact. Methods including inserting buffer layer, utilizing native oxides, and van der Walls transfer are introduced to form high quality and defect‐free dielectric layer.

Single-element two-dimensional (2D) tellurium (Te) which possesses an unusual quasi-one-dimensional atomic chain structure is a new member in 2D materials family. 2D Te possesses high carrier mobility, wide tunable bandgap, strong light-matter interaction, better environmental stability, and strong anisotropy, making Te exhibit tremendous application potential in next-generation electronic and optoelectronic devices. However, as an emerging 2D material, the research on fundamental property and device application of Te is still in its infancy. Hence, this review summarizes the most recent research progresses about the new star 2D Te and discusses its future development direction. Firstly, the structural features, basic physical properties, and various preparation methods of 2D Te are systemically introduced. Then, we emphatically summarize the booming development of 2D Te-based electronic and optoelectronic devices including field effect transistors, photodetectors and van der Waals heterostructure photodiodes. Finally, the future challenges, opportunities, and development directions of 2D Te-based electronic and optoelectronic devices are prospected.

Breakthroughs brought about by two‐dimensional (2D) materials in the field of photodetection have opened up new possibilities in infrared imaging. However, challenges still exist in fabricating high‐density detector arrays using such materials, which are essential for traditional imaging systems. In this study, we present a state‐of‐the‐art computing imaging system that utilizes a MoTe2/Si self‐powered photodetector coupled with flexible Hadamard modulation algorithms. This system demonstrates remarkable capability to produce high‐quality images in the shortwave infrared (SWIR) band, surpassing the capabilities of devices based on alternative material systems. The exceptional infrared imaging capability primarily stems from the MoTe2/Si photodetector's inherent features, including an ultra‐wide spectral range (265–1550 nm) and extremely high sensitivity (linear dynamic range (LDR) up to 123 dB, responsivity (R) up to 0.33 A W–1, external quantum efficiency (EQE) up to 43% and a specific detectivity (D*) exceeding 2.9 × 1011 Jones). Moreover, the imaging system demonstrates the ability to achieve high‐quality edge imaging of objects in the SWIR band (1550 nm), even in strong scattering environments and under low sampling rate conditions (sampling rate of 25%). We believe that this work will effectively advance the application scope of 2D materials in the field of computational imaging in SWIR bands. A high‐performance computational imaging system operating in the SWIR region, utilizing MoTe2/Si 2D‐3D Heterojunction‐Based Photodiode is developed. By incorporating the SPI algorithm, high‐resolution SWIR imaging and high‐quality image edge extraction at low sampling rates are achieved. Moreover, the system exhibits strong capability to penetrate imaging through scattering media, enabling high‐quality imaging in scattering environments under 1550 nm light.

ABSTRACT Two‐dimensional (2D) transition metal carbides, carbonitrides, and nitrides, known as MXenes, have been widely studied at the frontier of 2D materials. The excellent mechanical properties, electrical conductivity, excellent photoelectrical performance, and good thermal stability of MXenes enable wide applications in many fields, including but not limited to energy storage, supercapacitors, EMI shielding, catalysis, optoelectronics, and sensors. In particular, MXene‐based materials exhibit exceptional sensing performance due to their unique tunable surface chemistry, 2D architecture, and exotic electrical/mechanical/electromechanical properties, which are rarely found in other materials. This paper discusses the MXene sensing properties and their mechanisms in different types of sensors, including piezoresistive sensors, flexible sensors, gas sensors, and biosensors. The unique roles of these MXene‐based sensors toward the future of smart living are also outlined. This article may shed light on the rational design of MXene‐based sensors and provide valuable references for corresponding scenario applications. Two‐dimensional (2D) transition metal carbides, carbon‐nitrides, and nitrides (i.e., MXene) exhibit excellent mechanical properties, electrical conductivity, unique tunable surface chemistry, and two‐dimensional structure. MXene‐based material sensors demonstrate excellent sensing performance. This paper discusses the MXene sensing properties and their mechanisms of action in different types of sensors, outlining the unique role of these MXene‐based sensors in the future of smart living.

Photodetectors (PDs) are optoelectronic devices that convert optical signals into electrical responses. Recently, there has been a tremendous increase in research interest in PDs based on colloidal quantum dots (QDs) and two‐dimensional (2D) material heterostructures owing to the strong light‐absorption capacity and the well‐adjustable band gap of QDs and the superior charge carriers transfer ability of 2D materials. In particular, the heterojunction formed between QDs and 2D materials can effectively enhance the separation and transport of photogenerated charge carriers, which is expected to establish PDs with ultrahigh photoconductive gain, high responsivity, and detectivity. This review aimed to summarize the state‐of‐the‐art advances in the research of QDs/2D material nanohybrid PDs, including the device parameters, architectures, working mechanisms, and fabrication technologies. The progress of hybrid PDs based on the heterojunction of QDs with different 2D materials, along with their innovative applications, are comprehensively described. In the end, the challenges and feasible strategies in future research and development are briefly proposed. Heterostructures with tailored optoelectronic properties hold great potential in achieving high‐performance photodetector (PD) devices. This review summarizes recent advances in PDs based on heterostructures combining zero‐dimensional colloidal quantum dots with two‐dimensional materials, including basic device parameters, working mechanism, advanced fabrication techniques and various emerging optoelectronic applications, offering a promising strategy to promote the development of future optoelectronics.

A ferroelectric is a material with a polar structure whose polarity can be reversed (switched) by applying an electric field 1 , 2 . In metals, itinerant electrons screen electrostatic forces between ions, which explains in part why polar metals are very rare 3 – 7 . Screening also excludes external electric fields, apparently ruling out the possibility of ferroelectric switching. However, in principle, a thin enough polar metal could be sufficiently penetrated by an electric field to have its polarity switched. Here we show that the topological semimetal WTe 2 provides an embodiment of this principle. Although monolayer WTe 2 is centro-symmetric and thus non-polar, the stacked bulk structure is polar. We find that two- or three-layer WTe 2 exhibits spontaneous out-of-plane electric polarization that can be switched using gate electrodes. We directly detect and quantify the polarization using graphene as an electric-field sensor 8 . Moreover, the polarization states can be differentiated by conductivity and the carrier density can be varied to modify the properties. The temperature at which polarization vanishes is above 350 kelvin, and even when WTe 2 is sandwiched between graphene layers it retains its switching capability at room temperature, demonstrating a robustness suitable for applications in combination with other two-dimensional materials 9 – 12 . Two- and three-layer WTe 2 exhibits spontaneous out-of-plane electric polarization that can be switched electrically at room temperature and is sufficiently robust for use in applications with other two-dimensional materials.

Two-dimensional materials provide extraordinary opportunities for exploring phenomena arising in atomically thin crystals. Beginning with the first isolation of graphene, mechanical exfoliation has been a key to provide high-quality two-dimensional materials, but despite improvements it is still limited in yield, lateral size and contamination. Here we introduce a contamination-free, one-step and universal Au-assisted mechanical exfoliation method and demonstrate its effectiveness by isolating 40 types of single-crystalline monolayers, including elemental two-dimensional crystals, metal-dichalcogenides, magnets and superconductors. Most of them are of millimeter-size and high-quality, as shown by transfer-free measurements of electron microscopy, photo spectroscopies and electrical transport. Large suspended two-dimensional crystals and heterojunctions were also prepared with high-yield. Enhanced adhesion between the crystals and the substrates enables such efficient exfoliation, for which we identify a gold-assisted exfoliation method that underpins a universal route for producing large-area monolayers and thus supports studies of fundamental properties and potential application of two-dimensional materials. Here, the authors develop a one-step, contamination-free, Au-assisted mechanical exfoliation method for 2D materials, and isolate 40 types of single-crystalline monolayers, including elemental 2D crystals, metal-dichalcogenides, magnets and superconductors with millimetre size.