Publications

A two-terminal memristor memory based on a single VO2 nanowire is reported that can not only provide switchable resistances in a large range of about four orders of magnitude but can also maintain the resistances by a low bias voltage. The phase transition of the single VO2 nanowire was driven by the bias voltage of 0.34 V without using any heat source. The memristive behavior of the single VO2 nanowire was confirmed by observing the switching and non-volatile properties of resistances when voltage pulses and low bias voltage were applied, respectively. Furthermore, multiple retainable resistances in a large range of about four orders of magnitude can be utilized by controlling the number and the amount of voltage pulses under the low bias voltage. This is a key step towards the development of new low-power and two-terminal memory devices for next-generation non-volatile memories.

Abstract Private and security information for personal identification requires an encrypted tool to extend communication channels between human and machine through a convenient and secure method. Here, a triboelectric‐based transparent secret code (TSC) that enables self‐powered sensing and information identification simultaneously in a rapid process method is reported. The transparent and hydrophobic TSC can be conformed to any cambered surface due to its high flexibility, which extends the application scenarios greatly. Independent of the power source, the TSC can induce obvious electric signals only by surface contact. This TSC is velocity‐dependent and capable of achieving a peak voltage of ≈4 V at a resistance load of 10 MΩ and a sliding speed of 0.1 m s −1 , according to a 2 mm × 20 mm rectangular stripe. The fabricated TSC can maintain its performance after reciprocating rolling for about 5000 times. The applications of TSC as a self‐powered code device are demonstrated, and the ordered signals can be recognized through the height of the electric peaks, which can be further transferred into specific information by the processing program. The designed TSC has great potential in personal identification, commodity circulation, valuables management, and security defense applications.

Abstract Piezopotential‐assisted catalysis is of great significance for low cost and efficient catalysis processes. Here, Au x /BaTiO 3 plasmonic photocatalysts are fabricated by precipitating Au nanoparticles on piezoelectric BaTiO 3 nanocubes through a chemical approach. The Au nanoparticles (<8 nm) are decorated uniformly on the surface of BaTiO 3 , which endows the heterostructure with a wide light absorption from 300 to 600 nm. The photocatalytic properties of the heterostructures are investigated in detail toward methyl orange (MO) degradation. The Au content, piezoelectric potential of the BaTiO 3 substrate, and surface plasmon resonance (SPR) are confirmed to be vital to the photocatalytic activity. The Au 4 /BaTiO 3 shows an optimum photocatalytic performance for a complete degradation of MO in 75 min under full spectrum light irradiation with auxiliary ultrasonic excitation. The piezoelectric field originating from the deformation of BaTiO 3 further enhances the separation of photon‐generated carriers induced by SPR and promotes the formation of hydroxyl radicals, which results in a strong oxidizing ability of organic dyes. This work introduces the piezotronic effect to enhance plasmonic photocatalysis with Au x /BaTiO 3 heterostructures, which is ready to extend to other catalytic systems and offers a new option to design high‐performance catalysts for pollutant treatment.

Single crystal nanobelts of ZnO were synthesized and deposited onto 36/spl deg/ YX LiTaO/sub 3/ and 64/spl deg/ YX LiNbO/sub 3/ surface acoustic wave (SAW) devices for gas sensing applications. Sensor response, defined as the change in resonant frequency, was measured for H/sub 2/ and NO/sub 2/ between 20 and 200/spl deg/C. Measured sensor responses were 3.5 kHz towards 10 ppm NO/sub 2/ for a 64/spl deg/ LiNbO/sub 3/ SAW transducer operating at 160/spl deg/C and 3 kHz towards 1% H/sub 2/ for a 36/spl deg/ LiTaO/sub 3/ SAW transducer operating at 185/spl deg/C temperature.

Ocean waves are one of the most promising renewable energy sources for large-scope applications due to the abundant water resources on the earth. Triboelectric nanogenerator (TENG) technology could provide a new strategy for water wave energy harvesting. In this work, we investigated the charging characteristics of utilizing a wavy-structured TENG to charge a capacitor under direct water wave impact and under enclosed ball collision, by combination of theoretical calculations and experimental studies. The analytical equations of the charging characteristics were theoretically derived for the two cases, and they were calculated for various load capacitances, cycle numbers, and structural parameters such as compression deformation depth and ball size or mass. Under the direct water wave impact, the stored energy and maximum energy storage efficiency were found to be controlled by deformation depth, while the stored energy and maximum efficiency can be optimized by the ball size under the enclosed ball collision. Finally, the theoretical results were well verified by the experimental tests. The present work could provide strategies for improving the charging performance of TENGs toward effective water wave energy harvesting and storage.

A vapor phase transport growth process has been developed to synthesize ZnO quantum dots (QDs) on Si substrates. The characteristics were investigated for as-prepared ZnO QDs without any additional treatment. The formation of ZnO QDs with 6 nm in height and 15 nm in diameter is confirmed by scanning electron microscope and atomic force microscopy. Room-temperature photoluminescence reveals that the as-prepared ZnO QDs exhibit a predominant ultraviolet emission at 3.32 eV while the low energy defect-related blue-green emission is significantly quenched. The band gap of ZnO QDs is determined to be 3.41 eV, which evidently indicates the quantum confinement effects.

Despite the rapid advancements of soft electronics, developing compatible energy devices will be the next challenge for their viable applications. Here, we report an energy-harnessing triboelectric nanogenerator (TENG) as a soft electrical power source, which is simultaneously self-healable, stretchable, and transparent. The nanogenerator features a thin-film configuration with buckled Ag nanowires/poly(3,4-ethylenedioxythiophene) composite electrode sandwiched in room-temperature self-healable poly(dimethylsiloxane) (PDMS) elastomers. Dynamic imine bonds are introduced in PDMS networks for repairing mechanical damages (94% efficiency), while the mechanical recovery of the elastomer is imparted to the buckled electrode for electrical healing. By adjusting the buckling wavelength of the electrode, the stretchability and transparency of the soft TENG can be tuned. A TENG (∼50% stretchabitliy, ∼73% transmittance) can recover the electricity genearation (100% healing efficiency) even after accidental cutting. Finally, the conversion of biomechanical energies into electricity (∼100 V, 327 mW/m2) is demonstrated by a skin-like soft TENG. Considering all these merits, this work suggests a potentially promising approach for next-generation soft power sources.