Hierarchical Carbon Nanotube-Supported Conductive Metal–Organic Framework Nanosheet toward High-Strain Ionic Soft Actuator

Abstract

Conductive metal–organic frameworks (MOFs) have recently been applied in electroactive ionic actuators due to their high surface areas and fast ion migration. However, their actuation performance needs to be promoted in terms of high conversion efficiency and large strain. Here, a soft ionic actuator is assembled by designing a hierarchical Cu-MOFs-based active material, which is composed of conductive Cu-catecholate (Cu-CAT) nanosheets covalently bridged by carboxylic multiwall carbon nanotubes (Cu-CAT@MWCNT). Benefited from the large electromechanical deformation and rapid response rate of the Cu-CAT@MWCNT electrodes, the assembled soft actuator exhibits large displacement of 16.6 mm with high bending strain of 0.52% (AC of ±3 V) and a high energy conversion efficiency (3.02%) with cycling stability over 10 000 cycles (in frequency range of 0.1–10 Hz). In addition, it demonstrates the capacity of gripping objects when assembled on a robot. The Cu-CAT@MWCNT hybrid material-based electrode points out a feasible pathway to construct soft actuators with improved performance and broadens their applications.