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.

Toward Enhancing Performance of Electromagnetic Wave Absorption for Conductive Metal–Organic Frameworks: Nanostructure Engineering or Crystal Morphology Controlling

“…In addition, the characteristic peaks near 714 cm –1 can be attributed to the Cu–O stretching vibration. in which the oxygen atom is coordinated with the Cu 2+ . , As seen in Figures e and S1a3,b3, it is worth noting that the characteristic peak at 933.04 and 934.68 eV can be attributed to Cu + 2p 3/2 , and Cu 2+ 2p 3/2 in the Cu 2p spectrum. In addition, the peaks at 940.23 and 943.59 eV are two satellites of Cu + and Cu 2+ , respectively .…”

High-Performance Electrochemical Actuator under an Ultralow Driving Voltage with a Mixed Electronic–Ionic Conductive Metal–Organic Framework

“…Ni 3 (HITP) 2 -PP-EA exhibits a remarkable bending deformation with a center-to-center displacement of 5.8 mm and strain of 0.48% at a sine wave input voltage of ±0.5 V (Figure b,c), which are 11.6 times and 10.7 times, respectively, higher than those of PP-EA (0.5 mm, 0.045%), representing a top-level performance among the actuators reported so far. ,− The actuation performance of the Ni 3 (HITP) 2 -based EA under an input voltage of 0.5 V is superior to other MOF-based EAs even under a driving voltage of 3 V, sufficiently demonstrating the advantages of Ni 3 (HITP) 2 in developing EAs compared with other MOFs (Table S1). − Benefited from the high electronic conductivity of the electrode and long-range ordered pores of Ni 3 (HITP) 2 for fast ion transport, Ni 3 (HITP) 2 -PP-EA exhibits an obvious bending displacement of 1.2 mm even at an ultralow voltage of 0.1 V, representing the lowest driving voltage among reported MOF-based EAs. In comparison, the bending displacement of PP-EA could not be readily observed at input potentials lower than 0.5 V, demonstrating that the introduction of Ni 3 (HITP) 2 essentially enabled the EA to be driven at an ultralow voltage.…”

“…As one fast-growing subclass of metal–organic frameworks (MOFs), conductive MOFs (c-MOFs) have become the main focus of intensive research in electrochemical applications such as chemiresistive sensors, supercapacitors, and electrocatalysts owing to their high specific surface areas, extended electronic conjugation, and long-range ordered pores. − The strong charge delocalization of metal–ligand bonding and π–π stacked conjugation can offer conductive paths for fast electron transfer, enabling c-MOFs to serve as potential electrode materials for high-performance EAs. − In addition, the designability and versatility of c-MOFs will endow EAs with multifunctions. Althouth MOFs have been used to develop the EAs, − they either work under a relatively higher driving voltage or are fabricated by hydrization with a carbon nanotube or Mxene, restricting their application in low-energy and human-friendly devices. The development of ultralow voltage-driven EAs with c-MOF remains poorly explored due to the lack of MOFs with both high electronic and ionic conductivity.…”

Electrochemically-driven actuators: from materials to mechanisms and from performance to applications

“…Subsequently, the researchers developed another ionic actuator using Cu-MOFs, featuring Cu-CAT nanosheets linked by carboxylic MWCNTs (Cu-CAT@MWCNT). 354 The resulting IPMC, combined with EMITFSI/PVDF solid electrolyte, achieved a large 16.6 mm displacement and high bending strain (0.52%) under ±3 V AC voltage, with excellent cycling stability over 10 000 cycles (0.1–10 Hz). Furthermore, they demonstrated its ability to grip and transfer fragile objects on a robot (Fig.…”