Wei Zhong,Jin Zou,Yanyu Xie,Jing Yang,Mingfang Li,Shuwu Liu,Yansha Gao,Xiaoqiang Wang,Limin Lu
Herein, a highly sensitive and selective electrochemical sensor for the detection of benomyl (BN), a typical benzimidazole fungicide was proposed based on hierarchical nano-Cu x O decorated MWCNTs-COOH/MXene (nano-Cu x O-MWCNTs-COOH /MXene) composite. The ternary heterostructure presents good electrical conductivity, large specific surface area, and high catalytic activity, exhibiting excellent electrocatalytic activity with enhanced electrochemical signals towards the oxidation of BN. Besides, the embedded nano-Cu x O particles possess strong affinity toward benzimidazole molecules, which could promote the preconcentration of BN, further enhancing the sensitivity, as well as ensuring the high selectivity. Benefitting from the synergistic effect of components in the composite, the developed sensor presents a broad linear range from 10.0 nM to 10.0 μM with a low limit of detection of 3.0 nM (S/N = 3). Meanwhile, the nano-Cu x O-MWCNTs-COOH/MXene electrode also displays good long-term stability and repeatability. Furthermore, this method was successfully applied for the detection of BN in apple samples, illustrating its promising practicability.
A rationally designed MWCNT-COO-MXene/PNIPAM-PAM bilayer hydrogel actuator. • Covalent heterostructure enables rapid photothermal actuation and self-sensing. • Excellent mechanical strength and reversible biomimetic shape-morphing. • An integrated device couples NIR-driven motion with real-time resistance feedback. Stimulus-responsive hydrogels hold great potential in soft robotics, yet conventional PNIPAM hydrogels are limited by slow response speed, single functionality, and poor mechanical strength. Introducing photothermal fillers such as MXene and carbon nanotubes (CNTs) is an effective strategy to enhance their performance. However, conventional physical blending results in weak interfacial interactions, filler aggregation and limited performance enhancement. Here, we address this challenge by constructing a covalent MWCNTs-COOH@MXene heterostructure via EDC/NHS-mediated esterification, which serves as an efficient conductive and thermal network within the PNIPAM matrix and is firmly integrated with the polyacrylamide (PAM) passive layer through interfacial interpenetration. Compared with the physically blended counterpart, the covalently bonded hydrogel exhibits significantly enhanced thermal conductivity (1.49 W/(m·K)) and higher photothermal conversion efficiency (45.03%). The bilayer actuator exhibited rapid and reversible bending with a response time of 10 s, reaching a maximum bending angle of 420° under thermal stimulation and 80° under NIR light. The actuation amplitude could be controlled by adjusting the thickness ratio of the layers, temperature, and light parameters. Leveraging the efficient photothermal conversion and internal heat conduction of the MWCNTs-COOH@MXene heterostructure, the hydrogel achieved fast light-driven deformation and enabled biomimetic applications such as flower-like opening/closing, target grasping, and autonomous swimming. By integrating actuation and sensing functions, an NIR-light-controlled switch was realized that performed photomechanical actions while providing real-time state feedback through resistance monitoring. This work provides a new material platform and design strategy for high-performance soft robots and intelligent actuators with integrated functionalities. Download: Download high-res image (420KB) Download: Download full-size image
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