Tianpeng Ding

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.

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.

Robust and Low-Cost Flame-Treated Wood for High-Performance Solar Steam Generation

Solar-enabled steam generation has attracted increasing interest in recent years because of its potential applications in power generation, desalination, and wastewater treatment, among others. Recent studies have reported many strategies for promoting the efficiency of steam generation by employing absorbers based on carbon materials or plasmonic metal nanoparticles with well-defined pores. In this work, we report that natural wood can be utilized as an ideal solar absorber after a simple flame treatment. With ultrahigh solar absorbance (∼99%), low thermal conductivity (0.33 W m-1 K-1), and good hydrophilicity, the flame-treated wood can localize the solar heating at the evaporation surface and enable a solar-thermal efficiency of ∼72% under a solar intensity of 1 kW m-2, and it thus represents a renewable, scalable, low-cost, and robust material for solar steam applications.

Multilayered paper-like electrodes composed of alternating stacked mesoporous Mo2N nanobelts and reduced graphene oxide for flexible all-solid-state supercapacitors

Flexible all-solid-state supercapacitors (SCs) have great potential in flexible and wearable electronics due to their safety, flexibility, high power density, and portability. The energy storage properties of SCs are determined mainly by their composition and conductivity as well as the configuration of the integrated electrode material. Herein, a freestanding multilayered film electrode consisting of alternating stacked mesoporous Mo2N nanobelts and rGO nanosheets (MMNNBs/rGO) is described. The electrode has a high mass loading of 95.6 wt% of the Mo2N active material and boasts high areal capacitances of 142 and 98 mF cm−2 at current densities of 1 and 150 mA cm−2, respectively. All-solid-state SCs fabricated by sandwiching two thin and flexible freestanding MMNNBs/rGO hybrid electrodes with a poly (vinyl alcohol) (PVA)/H3PO4/silicotungstic acid (SiWA) gel electrolyte show a high volumetric capacitance of 15.4 F cm−3 as well as energy and power densities of 1.05 mW h cm−3 and 0.035 W cm−3 at a current density of 0.1 A cm−3 based on the volume of the entire cell. After 4000 charging–discharging cycles, the flexible SC retains 85.7% initial capacitance, thus exhibiting good cycling stability. This study provides a versatile method for the fabrication of flexible and high-performance ceramic-based nanohybrid films for SCs, and has immense potential in flexible and wearable electronics.

Induced Potential in Porous Carbon Films through Water Vapor Absorption

Sustainable electrical potential of tens of millivolts can be induced by water vapor adsorption on a piece of porous carbon film that has two sides with different functional group contents. Integrated experiments, and Monte Carlo and ab initio molecular dynamics simulations reveal that the induced potential originates from the nonhomogeneous distribution of functional groups along the film, especially carboxy groups. Sufficient adsorbed water molecules in porous carbon facilitate the release of protons from the carboxy groups, resulting in a potential drop across the carbon film because of the concentration difference of the released free protons on the two sides. The potential utilization of such a phenomenon is also demonstrated by a self-powered humidity sensor.

Self-Powered Multimodal Temperature and Force Sensor Based-On a Liquid Droplet

Herein we report a self-powered multimodal temperature and force sensor based on the reverse electrowetting effect and the thermogalvanic effect in a liquid droplet. The deformation of the droplet and the temperature difference across the droplet can induce an alternating pulse voltage and a direct voltage, respectively, which is easy to separate/analyze and can be utilized to sense the external force and temperature simultaneously. In addition, an integral display system that can derive information from external temperature/force concurrently is constructed. Combined with advantages of excellent sensing properties and a simple structure, the droplet sensor has promising applications in a wide range of intelligent electronics.