Scalable in situ electrochemical deposition of polypyrrole on single-walled carbon nanotubes

Introduction: Silver membrane filter (SMF), characterized by its porous yet interconnected microstructure, was utilized as a novel conductive platform for the in situ functionalization of single-walled carbon nanotubes (SWNTs). The main objective of this study was to achieve highly uniform, conformal polymer encapsulation over advanced carbonaceous nanomaterials without compromising their pristine graphitic structures. Materials and methods: Raw SWNTs were chemically pretreated with a mixture of H 2 O 2 and HCl to enhance microstructural and electronic homogeneity. The pretreated nanotubes were subsequently distributed and immobilized across the SMF surface via simple vacuum filtration. Leveraging the high electrical conductivity of the SMF framework, the nanotube-loaded membrane directly served as a working electrode to execute in situ electropolymerization of pyrrole on the surface of SWNTs. Results: Scanning electron microscopy (SEM) revealed a systematic thickness propagation over time, culminating at 1000 s in a continuous coaxial core–shell morphology with a uniform outer diameter of approximately 45 nm and an average polymer shell thickness of 12.5 nm. Energy-dispersive X-ray spectroscopy (EDX) and CHN elemental analysis successfully verified the qualitative nitrogen emergence and quantified a stable doped polymer phase loading of approximately 17.60 wt% (comprising 11.70 wt% organic PPy backbone and 5.90 wt% intercalated perchlorate ions). Raman spectroscopy corroborated that the custom chemical pretreatment narrowed the G-band FWHM from 114.4 to 80.2 cm −1 and dropped the I D /I G ratio from 0.10 to 0.08, providing definitive physical proof that localized metallic scattering anomalies were suppressed to prevent erratic current crowding. Conclusions: Under the described conditions, pairing the conductive silver membrane with a mild chemical pretreatment provides an efficient and scalable processing route to generate uniform coaxial core–shell nanocomposites. These results demonstrate that combining liquid-phase vacuum filtration with in situ electropolymerization governs mass transport successfully, bypassing multi-step vapor printing thresholds to deliver advanced nanocomposites with great potentials in energy storage and bio-recognition applications.