Electrochemical Actuators with Multicolor Changes and Multidirectional Actuation.

Electrochemical (EC) actuators have garnered significant attention in recent years, yet there are still some critical challenges to limit their application range, such as responsive time, multifunctionality, and actuating direction. Herein, an EC actuator with a back-to-back structure is fabricated by stacking two membranes with bilayer V O nanowires/single-walled carbon nanotubes (V O NWs/SWCNTs) networks, and shows a synchronous high actuation amplitude (about ±9.7 mm, ±28.4°) and multiple color changes. In this back-to-back structure, the inactive SWCNTs layer is used as a conductive current collector, and the bilayer network is attached to a porous polymer membrane. The dual-responsive processes of V O nanowires (V O NWs) actuation films and actuators are also deeply investigated through in situ EC X-ray diffraction and Raman spectroscopy. The results show that the EC actuation of the V O NWs/SWCNTs film is highly related to the redox behavior of the pseudocapacitive V O NWs layer. At last, both V O NWs and W O nanowires (W O NWs)-based EC actuators are constructed to demonstrate the multicolor changes and multidirectional actuation induced by the opposite lattice changes of V O NWs and W O NWs during ionic de-/intercalation, guiding the design of multifunctional EC actuators in the future.