Heterogeneous interface mismatch-enhanced metal-organic frameworks (MOFs)-based electrochemical actuators

Abstract

Limited by the existing electrode nanostructures, electrochemical actuators (EAs) can hardly work with high response rate, while maintaining large deformations under low driving voltages. Herein, this challenge is overcome via constructing the heterogeneous interface mismatch of 2D Cu3(HHTP)2 MOFs and 3D Cu(OH)2 nanotubes for the first time. The mismatch of the spatial configurations at the heterogeneous interface leads to the modulation in nanostructures and thereby arrays of MOFs’ crystals. Consequently, the 2D Cu3(HHTP)2 is tailored for integrating not only an inherent high porosity, but also a controllable crystal size, uniform distribution, and few layers-stacking structure, all of which contribute to the rate and quantity of migrated ions. Experiments indicate that the EA exhibits a large voltage-dependent deformation (0.463 mm−1 V−1), a high response rate (0.031 mm−1 s−1 V−1), an ultra-low driving voltage (−0.2 V), and an upper limit of working frequency range as high as 20 Hz. Moreover, a mechanical stress of 19.24 MPa and an energy density of 23.94 kJ m−3 at continuous working condition (−0.3 V, 0.01 Hz) are also achieved, further enabling the EA to actuate a block over 25 times heavier than itself easily. By introducing a new strategy for improving EAs’ performance, this research promotes the potential application of next-generation EAs.