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The clean production of hydrogen from water using sunlight has emerged as a sustainable alternative toward large-scale energy generation and storage. However, designing photoactive semiconductors that are suitable for both light harvesting and water splitting is a pivotal challenge. Atomically thin transition metal dichalcogenides (TMD) are considered as promising photocatalysts because of their wide range of available electronic properties and compositional variability. However, trade-offs between carrier transport efficiency, light absorption, and electrochemical reactivity have limited their prospects. We here combine two approaches that synergistically enhance the efficiency of photocarrier generation and electrocatalytic efficiency of two-dimensional (2D) TMDs. The arrangement of monolayer WS

Single-metal-atom chains (SMACs), as the smallest one-dimensional structure, have intriguing physical and chemical properties. Although several SMACs have been realized so far, their controllable fabrication remains challenging due to the need to arrange single atoms in an atomically precise manner. Here we develop a chemical vapour co-deposition method to construct a wafer-scale network of platinum SMACs in atom-thin films. The obtained atomic chains possess an average length of up to ~17 nm and a high density of over 10 wt%. Interestingly, as a consequence of the electronic delocalization of platinum atoms along the chain, this atomically coherent one-dimensional channel delivers a metallic behaviour, as revealed by electronic measurements, first-principles calculations and complex network modelling. Our strategy is potentially extendable to other transition metals such as cobalt, enriching the toolbox for manufacturing SMACs and paving the way for the fundamental study of one-dimensional systems and the development of devices comprising monoatomic chains. Agency for Science, Technology and Research (A*STAR) Ministry of Education (MOE) National Research Foundation (NRF) Submitted/Accepted version This work was supported by the support from National Research Foundation Singapore programme NRF-CRP22-2019-0007 and NRF-CRP21-2018-0007. This work is also supported by the Ministry of Education, Singapore, under its AcRF Tier 2 (MOE2019-T2-2-105) and AcRF Tier 1 RG4/17 and RG7/18. This research is also supported by A*STAR under its AME IRG Grant (Project No. A2083c0052). The work at NUAA was supported by the National Key Research and Development Program of China (2019YFA0705400), National Natural Science Foundation of China (11772153, 22073048), the Natural Science Foundation of Jiangsu Province (BK20190018), and a Project by the Priority Academic Program Development of Jiangsu Higher Education Institutions. W.Z. acknowledges the support of the Beijing Outstanding Young Scientist Program (BJJWZYJH01201914430039). B.T. and X.W. acknowledge the support from the Ministry of Education, Singapore (MOE2019 T1-001-113). H.Y. and M. N. acknowledge the support from the Hong Kong Research Grant Council, Hong Kong (HKRGC GRF 12300218, 12300519, 17201020, 17300021, and UGC-RMGS 207300829). H.D. acknowledges the support from German Research Foundation (DFG) under the Grant SFB917 Nanoswitches.

Control of the precursor transport through oxygen dosing yields increased MoS2 coverage and increased connectivity between crystalline MoS2 domains.

Scheme and band diagram for Au NPs combined with a CuxO thin film are synthesized by a self-assembly process and electrochemical modification. Au/CuxO for developing carbon capture and storage performance.

Two-dimensional (2D) materials and their heterostructures exhibit intriguing optoelectronic properties; thus, they are good platforms for exploring fundamental research and further facilitating real device applications. The key is to preserve the high quality and intrinsic properties of 2D materials and their heterojunction interface even in production scale during the transfer and assembly process so as to apply in semiconductor manufacturing field. In this study, we successfully adopted a wet transfer existing method to separate mediator-assisted wafer-scale from SiO2/Si growing wafer for the first time with intermediate annealing to fabricate wafer-scale MoS2/h-BN and WS2/h-BN heterostructures on a SiO2/Si wafer. Interestingly, the high-quality wafer-scale 2D material heterostructure optical properties were enhanced and confirmed by Raman and photoluminescence spectroscopy. Our approach can be applied to other 2D materials and expedite mass production for industrial applications.

It has been demonstrated that the WS2 monolayer is an excellent template for AlN epitaxy at 400 °C low temperature. Low-temperature AlN thin films exhibit much superior crystalline quality than those grown directly on sapphire substrates. In addition to the small lattice mismatch between AlN and WS2 monolayer, we proposed a growth mechanism to explain the excellent van der Waal epitaxy by looking at the initial growth. This growth model reveals that transition metal dichalcogenides (TMDCs) are promising buffer layers for the deposition of III-nitrides but also suggests the novel combination of AlN and TMDCs in the research of future 2D field-effect transistors due to the extremely low leakage current of high-quality AlN films.

We report fabrication and measurements of single-layer SnSe2/chemical vapor deposition (CVD) graphene/hexagonal boron nitride (h-BN) field-effect device. The coherent magnetotransport properties of such a hybrid system are systematically studied so as to obtain a good understanding of the structure which may find potential applications in thermoelectricity, flexible electronics, quantum coherent sensor as well as stress sensing. We observed weak localization well described by the Hikami-Larkin-Nagaoka model and the phase coherence length is around 540 nm for V BG = −20 V at 1 K. The phase coherence length could be effectively changed by controlling the temperature and gate voltage. We also obtain good field-effect dependent properties of atomic-scale SnSe2 ultrathin film/graphene system. Given the current challenges in tuning single-layer SnSe2/CVD graphene on h-BN with a suitable dielectric layer, our results suggest the potential of quantum coherent effect, an effective way for development of future quantum nano-switch device.

Optical rectennas extend the electromagnetic wave rectification process into the visible regime and provide a route toward high-performance photodetection and energy harvesting. Here, the promise of 2D materials toward on-chip optical rectennas is demonstrated. A self-aligned patterning process yields lateral MIM structures where a nanometer-sized air gap separates a 2D material contact from a metal electrode. This device can be scalably produced in large arrays using established microfabrication techniques. Different from previous approaches, the performance of the 2D rectenna can be adjusted through electrostatic gating. Optimization of the band alignment leads to strong rectification at wavelengths around 500 nm and clear polarization control. Comparison of wavelength-dependent rectenna performance with a photon-assisted tunneling model reveals a tenfold increase in photon-electron coupling over nanotube-based rectennas. The results highlight the potential of 2D material-based rectennas for future quantum computing applications.

Graphene is widely used as a barrier at the solid–solid and gas–solid state interface. However, the use of graphene as a barrier at the liquid–solid interface has been rarely reported, particularly in the case of a liquid-state metal and a solid-state metal interface. Herein, a graphene layer is synthesized on a Cu foil, and single-layer and bilayer graphene is detected via Raman spectroscopy. The interfacial intermetallic compound between eutectic Sn–58Bi alloy with a melting temperature of 138 °C and Cu with a melting temperature of 1085 °C can be significantly suppressed by graphene using different reflow temperatures (180°C and 300°C) and reflow times (144–625 s). Cu diffusion through graphene is visible in the Sn–Cu intermetallic compound (IMC) formations in the SB58 solder and at the interface after the reflow processes. We found that the activation energy of Cu diffusion through graphene into the liquid-state graphene is ∼32.6 kJ/(mol∙k), which is higher than that attained without graphene. Therefore, the findings of this study show that graphene is a promising diffusion barrier for the liquid–solid interface.