Longyan Yuan

Flexible solid-state supercapacitors based on carbon nanoparticles/MnO2 nanorods hybrid structure.

A highly flexible solid-state supercapacitor was fabricated through a simple flame synthesis method and electrochemical deposition process based on a carbon nanoparticles/MnO(2) nanorods hybrid structure using polyvinyl alcohol/H(3)PO(4) electrolyte. Carbon fabric is used as a current collector and electrode (mechanical support), leading to a simplified, highly flexible, and lightweight architecture. The device exhibited good electrochemical performance with an energy density of 4.8 Wh/kg at a power density of 14 kW/kg, and a demonstration of a practical device is also presented, highlighting the path for its enormous potential in energy management.

Polypyrrole-coated paper for flexible solid-state energy storage

Highly conductive paper was fabricated through polypyrrole (PPy) coating on common printing paper by a simple and low-cost “soak and polymerization” method. The as-fabricated porous, flexible and conductive paper shows a high electrical conductivity of 15 S cm−1 and a low sheet resistance of 4.5 Ω sq−1. Flexible solid-state supercapacitors assembled with PPy/paper composite electrodes had an average weight of 55 mg and an areal capacitance of 0.42 F cm−2, indicating a high energy density of 1 mW h cm−3 at a power density of 0.27 W cm−3 normalized to the volume of the whole cell (electrode, electrolyte, and separator). Furthermore, this method could be easily scaled up to large-scale fabrication of conductive paper and opened up new opportunities for flexible energy storage.

Paper-Based Supercapacitors for Self-Powered Nanosystems†

Energy storage on paper: paper-based, all-solid-state, and flexible supercapacitors were fabricated, which can be charged by a piezoelectric generator or solar cells and then discharged to power a strain sensor or a blue-light-emitting diode, demonstrating its efficient energy management in self-powered nanosystems.

High‐Strain Sensors Based on ZnO Nanowire/Polystyrene Hybridized Flexible Films

A type of strain sensor with high tolerable strain based on a ZnO nanowires/polystyrene nanofibers hybrid structure on a polydimethylsiloxane film is reported. The novel strain sensor can measure and withstand high strain and demonstrates good performance on rapid human-motion measurements. In addition, the device could be driven by solar cells. The results indicate that the device has potential applications as an outdoor sensor system.

Three-dimensional WO3 nanostructures on carbon paper: photoelectrochemical property and visible light driven photocatalysis.

Three-dimensional (3D) WO(3) nanostructures were grown on carbon paper by a catalyst-free high temperature reactive vapor deposition process, which exhibit a good photoelectrochemical property and visible light driven photocatalytic performance.

Water-evaporation-induced electricity with nanostructured carbon materials

Water evaporation is a ubiquitous natural process that harvests thermal energy from the ambient environment. It has previously been utilized in a number of applications including the synthesis of nanostructures and the creation of energy-harvesting devices. Here, we show that water evaporation from the surface of a variety of nanostructured carbon materials can be used to generate electricity. We find that evaporation from centimetre-sized carbon black sheets can reliably generate sustained voltages of up to 1 V under ambient conditions. The interaction between the water molecules and the carbon layers and moreover evaporation-induced water flow within the porous carbon sheets are thought to be key to the voltage generation. This approach to electricity generation is related to the traditional streaming potential, which relies on driving ionic solutions through narrow gaps, and the recently reported method of moving ionic solutions across graphene surfaces, but as it exploits the natural process of evaporation and uses cheap carbon black it could offer advantages in the development of practical devices.

Top-Gate Low-Threshold Voltage

Copper oxide (Cu<i>x</i>O) thin films were grown on SiO₂/Si substrate by pulsed laser deposition under different substrate temperatures. Top-gate Cu<i>x</i> O semiconductor thin-film transistors (TFTs) were fabricated with high- κ HfON as gate dielectric. The performance of Cu₂O TFTs was improved due to increased Hall mobility resulting from the decreased scattering of both the ionized defects and the grain boundary for Cu₂O channel films. The <i>p</i>-channel pure polycrystalline Cu₂O TFTs (<i>W</i>/<i>L</i> = 500 μm/20 μm) exhibited a low threshold voltage of -0.8 V, an on-off current ratio of 3 x 10⁶, a saturation mobility of 4.3 cm²/ V s, and a subthreshold swing of 0.18 V/decade.

p\hbox{-}\hbox{Cu}_{2} \hbox{O}

n-ZnO/p-silicon nanowire (SiNW) photodiodes were prepared by radio frequency reactive magnetron sputtering of n-type zinc oxide at room temperature on photoresist filled p-SiNWs, which were fabricated by electroless metal deposition method at 323 K. Our n-ZnO/p-SiNW photodiodes showed good temperature- and light-intensity dependence. They exhibited strong responsivities of 19.2 and 2.5 A/W for 254 and 1000 nm photons, respectively, under a reverse bias of 2 V with a strong peak of responsivity near 390 nm, the wavelength corresponding to the band gap of ZnO. These results present potential applications of n-ZnO/p-SiNW photodetectors in deep ultraviolet and near infrared regions.

Thin-Film Transistor Grown on

N-ZnO nanorods/n-silicon heterojunction was fabricated by growth of ZnO nanorods on a n-type silicon (111) wafer with a low-temperature aqueous solution method. Capacitance-voltage measurements revealed that after annealing at 900 °C in O2 ambient for 1 h, the heterojunction changed from abrupt N-ZnO nanorods/n-silicon to graded P-ZnO/n-silicon junction. The annealed diode showed good photoresponse in both the ultraviolet and visible regions with responsivity around 0.3 and 0.5 A/W without bias. The photoresponses toward ultraviolet and visible light were enhanced when the diode was under reverse and forward bias, respectively. The results were discussed in terms of phosphorus diffusion process and the band diagrams of the heterojunctions in this work.

\hbox{SiO}_{2}/ \hbox{Si}

The field emission (FE) properties of carbon nanotube (CNT) bundle arrays grown on vertically self-aligned ZnO nanorods (ZNRs) are reported. The ZNRs were first synthesized on ZnO-seed-coated Si substrate by the vapour phase transport method, and then the radically grown CNTs were grown directly on the surface of the ZNRs from ethanol flames. The CNT/ZNR composite showed a turn-on field of 1.5?V??m?1 (at 0.1??A?cm?2), a threshold field of 4.5?V??m?1 (at 1?mA?cm?2) and a stable emission current with fluctuations of 5%, demonstrating significantly enhanced FE of ZNRs due to the low work function and high aspect ratio of the CNTs, and large surface-to-volume ratio of the underlying ZNRs.