Flexible electronic skin (e-skin) have been widely researched due to their potential applications in wearable electronics, robotic systems, biomedicines, et al. For realization of lower cost of the e-skin, copper nanowires (CuNWs) are often served as conductive fillers since their high conductivity and flexibility. However, CuNWs are very sensitive to oxygen that greatly hinders their developments. To solve this issue, a facile galvanic replacement reaction without any heating, stirring or dispersant was performed to coat a thin layer of silver (20 nm) on the surface of CuNWs and Cu-Ag core-shell nanowires (Cu-Ag NWs) with excellent oxidation resistance were obtained and served as conductive fillers for e-skin. To further increase the sensitivity and reduce the response time and detection limit, micro-structure of the surface of rose petal was replicated and introduced onto 2D polydimethylsiloxane (PDMS) surface. The bio-inspired piezoresistive e-skin demonstrates high sensitivity (1.35 kPa -1 ), very low detection limit (< 2 Pa), very low response time and relaxation time (36 ms and 30 ms) and outstanding working stability (more than 5000 cycles). The high performance e-skin has extensive applications in voice recognition, wrist pulses monitoring and detection of spatial distribution of pressure.−1 ), fast response (<500 ms) and low detection limit (20 mg). 29 Wang, et al. replicated the surface of silk and constructed a piezoresistive e-skin, which can be used as voice The defining feature of our design is that the length of the CuNWs should not larger than 20 μm. Therefore, a lower EDA concentration (95 mM) and shorter reaction time (<1.0 h) was performed to synthesis shorter CuNWs. Fig.1a and b show the

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As group III-nitride semiconductors are thinned to only a few atomic layers, regarding as 2D materials, it would lead to an ultrawide bandgap (E g ) due to the quantum confinement effect, [11,12] which can be used as ultraviolet optoelectronic devices needed ultrawide E g semiconductors. [13,14] Moreover, 2D group III-nitride semiconductors showing anomalously temperature-dependent thermal conductivity and orbitally driven ultra-low thermal conductivity have been predicted, [15,16] which make them prospective for applications in energy conversion, for example, thermos-electrics. [17] However, the experimental synthesis of 2D group III-nitride semiconductors is still meeting with tremendous difficulties due to the fact that group III-nitride semiconductors more easily orientate along c-axis than any other axis [18] and the lateral mobility for precursor atoms of group III-nitride materials, i.e., AlN, is very low, [19] which result in the formation of 3D crystal structure. Moreover, the surface energy constraint and large lattice mismatch between group III-nitride semiconductors and substrates would also lead to the formation of 3D island crystal. [11] In this work, we have successfully realized the epitaxial growth of 2D AlN layers sandwiched between graphene and Si substrates for the first time in the world by metal organic chemical vapor deposition (MOCVD). On the one hand, Si (111) surface with high symmetry [20] has stable adsorption sites for Al and N adatoms, Figure S1 in the Supporting Information. On the other hand, Si has a lattice mismatch with AlN(0001) of ≈19%, [21] Figure S2 in the Supporting Information, producing the tensile stress together with the effect of Gibbs free energy that drive the crystal structure of 2D AlN transforming from R3m structure to P6 3 MC structure. [22][23][24] During the growth process, hydrogenation for graphene/Si hetero-structures with hydrogen (H 2 ) guarantees the formation of 2D AlN layers. The 2D AlN layers are sandwiched between graphene and Si substrates after hydrogenation, while no interlayer can be found between graphene and Si substrates without hydrogenation. To further study the formation mechanism of 2D AlN layers and the effect of hydrogenation on the formation of 2D AlN layers, theoretical calculations with first-principles calculations based on density functional theory (DFT) have been carried out. We further predicted and determined the E g of the 2D AlN layers theoretically and experimentally by Hartree-Fock local density

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A vacuum-assisted layer-by-layer superhydrophobic MWCNT film with excellent electrothermal and photothermal performances was fabricated for fast-speed deicing and controllable manipulation.

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Integration of one-dimensional (1D) semiconductors with two-dimensional (2D) materials into hybrid systems is identified as promising applications for new optoelectronic and photodetection devices. Herein, a selfintegrated hybrid ultraviolet (UV) photodetector based on InGaN nanorod arrays (NRAs) sandwiched between transparent top and back graphene contacts forming a Schottky junction has been demonstrated for the first time. The controlled van der Waals epitaxy of the vertically aligned InGaN NRA assembly on graphene-on-Si substrates is achieved by plasma-assisted molecular beam epitaxy. Moreover, the self-assembly formation mechanisms of InGaN NRAs on graphene are clarified by theoretical calculations with first-principles calculations based on density functional theory. The peculiar 1D/2D heterostructure hybrid system-based integrated UV photodetector simultaneously exhibits ultrafast response time (∼50 μs) and superhigh photosensitivity (∼10 5 A/W). It is highly believed that the concept proposed in this work has a great potential and can be widely applied for the next-generation integrated 1D/2D nano-based optoelectronic and photodetection devices.