Skin-inspired cellulose-based hydrogel design with hydrophobic-conductive synergy for enhanced electrochemical nanoplastic removal

In aquatic environments, traditional cellulose-based hydrogels face structure change challenges due to excessive swelling caused by hydrophilic groups, resulting in poor conductivity and limiting their electrochemical applications. To overcome these challenges, this study presents a bioinspired carboxymethyl cellulose/polyacrylamide/butyl acrylate/polyaniline (CMC/PAM/BA/PANI) composite hydrogel, mimicking the smart responsive interface of hydrophobic human skin. When applied in the electrochemical capture of nanoplastic in wastewater, the flexible CMC/PAM network resembles the subcutaneous layer as the substrate, the BA's hydrophobic long-chain esters allow for selective nanoplastic interaction, while the PANI component at the outmost surface enables conductive charge transfer for precise adsorption control, achieving a superior 96% removal efficiency for polystyrene nanoplastic (1 mg/L) at 1  V with good reusability. This biomimetic design synergistically combines electrostatic adsorption, hydrophobic interactions, and π-π stacking interactions. Mechanism studies reveal pseudo-second-order kinetics with Freundlich-dominated adsorption. The biomimetic design, inspired by skin's layered structure and functionality, achieves intelligent and efficient nanoplastic removal through precisely engineered interfacial interactions, offering new perspectives for advanced water purification technologies.