Converting ubiquitous environmental energy into electric power holds tremendous social and financial interests. Traditional energy harvesters and converters are limited by the specific materials and complex configuration of devices. Herein, it is presented that electric power can be directly produced from pristine graphene oxide (GO) without any pretreatment or additives once encountering the water vapor, which will generate an open-circuit-voltage of up to 0.4-0.7 V and a short-circuit-current-density of 2-25 µA cm on a single piece of GO film. This phenomenon results from the directional movement of charged hydrogen ions through the GO film. The present work demonstrates and provides an extremely simple method for electric energy generation, which offers more applications of graphene-based materials in green energy converting field.

Graphene, because of its superior electrical/thermal conductivity, high surface area, excellent mechanical flexibility, and stability, is currently receiving significant attention and benefit to fabricate actuator devices. Here, a sole graphene oxide (GO) film responsive actuator with an integrated self-detecting sensor has been developed. The film exhibits an asymmetric surface structure on its two sides, creating a promising actuation ability triggered by multistimuli, such as moisture, thermals, and infrared light. Meanwhile, the built-in laser-writing reduced graphene oxide (rGO) sensor in the film can detect its own deformation in real time. Smart perceptual fingers in addition to rectangular-shaped and even four-legged walking robots have been developed based on the responsive GO film.

Large-scale assembly of graphenes in a well-controlled macroscopic fashion is important for practical applications. We have developed a facile and straightforward approach for continuous fabrication of neat, morphology-defined, graphene-based hollow fibers (HFs) via a coaxial two-capillary spinning strategy. With a high throughput, HFs and necklace-like HFs of graphene oxide have been well-controlled produced with the ease of functionalization and conversion to graphene HFs via simply thermal or chemical reduction. This work paves the way toward the mass production of graphene-based HFs with desirable functionalities and morphologies for many of important applications in fluidics, catalysis, purification, separation, and sensing.

wileyonlinelibrary.comconversion that only relies on the ambient spontaneous moisture diffusion process greatly avoids the disturbances (e.g., thermal, mechanical variation, and so on) from the environment, which is of significance for the future high stable electric power supply. Therefore, to further satisfy the increasing demands for electric power, the effort on exploring and researching new versatile candidates (not just limited in a single less-conductive material, such as GO) for various vapor-electric energy generation is urgent, which has been absent so far yet.Conducting polymers have attracted numerous attention in the applications of actuators, sensors, batteries, supercapacitors, and electrochromic devices due to their predominant mechanical, optical, redox, and electrical properties. [12][13][14][15] In particular, polypyrrole (PPy) has been widely studied in energy conversion fields because of its significant advantages of easy synthesis, wide range of dopant species, and relatively good environmental stability. [16] For instance, PPys can act as a kind of hygroscopic material to capture the moisture from the ambient environment, [15,17,18] where its dominant ionic conductivity enhances with the increase of relative humidity (RH). Furthermore, PPys could promote the conversion of electrical to mechanical energy in the form of actuation behaviors induced by the volume change resulting from a Faradaic doping and undoping process. [19] Meanwhile, the doped and undoped anions lead to different conducting states of PPy, in which the energy gap reduces from 4 to ≤2.5 eV according to the state from undoped (neutral) to doped (oxidation). [20,21] The reversible switching process between the doped (oxidized) state and undoped (neutral) state of PPy can be controlled by changing the electrical potential as well as the doping level. [22] These results indicate the strong interactions of PPy and doped anions to tune the functions of PPy-based devices that provide the opportunities for developing new generation energy-converting systems.In this work, we have developed a high-performance vaporactivated power generator (VaPG) based on a 3D PPy framework with a preformed anion gradient (named as gradient 3D PPy, g-3D-PPy). The g-3D-PPy was formed by electrolyte/electric field coinduced by the gradient process of anions doped in the 3D PPy framework containing LiClO 4 aqueous solution (this strategy here is called electrolyte-electric annealing, EeA process). [10,22] Upon exposure to the water vapor, the open porous network can greatly facilitate the diffusion of water molecules, and meanwhile the anion-containing gradient provides free ionic gradient to promote the spontaneous transport An efficient vapor-activated power generator based on a 3D polypyrrole (PPy) framework was demonstrated for the first time. By constructing the anions gradient in the PPy, this specially designed PPy framework provided free ionic gradient with the assistant of absorbing water vapor to promote the spontaneous transport of ionic char...

Traditional flame-retardant materials often show poor tolerance to oxidants, strong acidic/alkaline reagents, organic solvents, along with toxicity problems. Herein, highly fire-retardant ultralight graphene foam has been developed, which possesses not only ultralight and compressible characteristics but also efficient flame-retardant properties, outperforming those traditional polymer, metallic oxide, and metal hydroxide based flame retardant materials and their composites. The newly developed unconventional refractory materials are promising for specific applications as demonstrated by the observed high temperature resistant microwave absorption capability.