Interactions between Graphene‐Based Materials and Water Molecules toward Actuator and Electricity‐Generator Applications

Abstract

of chemical energy to electric and/or mechanical energy, which is potentially profitable for various applications such as sensors, actuators, robots, switches, artificial muscles, and electricity generators. [22, Benefiting from the large available surface area, the unique electrical, thermal, and mechanical properties of graphene and/or its derivatives, as well as the ease of structure functionalization, device-oriented applications based on the interactions between graphene materials and water molecules have become of increasing concern. [61-66] However, no review has focused on the interactions between graphene/its derivatives and water molecules for actuation and electricity-generation applications so far. In this regard, we herein summarize the progress on moistureinduced deformable actuators and water-enabled electric generators achieved in recent years. The working mechanisms of actuators and electric generators will be introduced. The challenges and the potential trends in fabricating future devices on the basis of the effective interactions between graphene derivatives and water molecules are also discussed.The authors declare no conflict of interest.

The Application of Stimuli-Sensitive Actuators Based on Graphene Materials

“…Artificial actuators are stimuli-sensitive devices that can undergo a reversible change in shape, volume, modulus, or some other mechanical properties in response to various external stimuli, which have attracted tremendous attentions attribute to the wide applications for robots, intelligent switch, smart sensors, memory chips, and prosthetic devices (Kim and Lieber, 1999;Jang et al, 2008;Huang et al, 2012;Xue et al, 2015;Xu et al, 2018b). Usually, the external stimuli can be electrical, optical, thermal, humid, and other forms of stimulation depending on the actuation mechanism (Huang et al, 2012).…”

“…Graphene, as another carbon nanomaterial with just one atom layer thick, that features high electron conductivity, excellent mechanical flexibility, huge surface area, superior thermal conductivity and stability, has captured a broad research interest for using as material or structural component in the actuator fabrication (Novoselov et al, 2004;Zan et al, 2011;Cheng et al, 2016;Xu et al, 2018b;Liu Y. Q. et al, 2019). It could be not only served as the electrode in the electrically/electrochemically driven actuators, but also the energy converting component or active actuation component in the photothermal systems, as well as in the moisture actuators (Yang et al, 2018).…”

A three-dimensional hollow graphene fiber microelectrode with shrink-effect-enabled enzyme immobilization for sensor applications

“…It was recently reported that the hydration and/or dehydration of graphene-based materials could trigger the deformation of graphene sheets [8], which is potentially profitable for enzyme immobilization. Based on these concepts, we present an electrochemical enzyme sensor based on a 3D porous graphene coated hollow graphene fiber (PHGF) via a simple and effective shrink-effect-enabled enzyme immobilization method.…”

“…After drying, chemically reduced graphene oxide (RGO) aggregated along the Cu wire (RGO/Cu, Fig. 1b) due to the spontaneous redox reaction between GO and Cu [8]. The etching of Cu wire in a mixture of FeCl 3 and HCl aqueous solution resulted in the formation of hollow graphene fiber (Fig.…”

“…1e). Then, dehydration-responsive shrinking of graphene sheets in the 3D graphene occured in the following drying process due to the stretching and rotating of carbon-carbon bonds [8]. In this way, GOD was successfully immobilized on the PHGF (named as GOD/PHGF, Fig.…”