Sustainable Fluorinated Silicon Dielectric Design for Enhanced Contact-Electro-Chemistry

Solid-liquid contact electrification (CE) has recently emerged as a powerful means of initiating interfacial chemical reactions via charge transfer. Fluorinated ethylene propylene (FEP) and polytetrafluoroethylene (PTFE) are frequently employed as solid dielectrics owing to their fluorine-rich surfaces, which exhibit strong electron-withdrawing characteristics. However, their high environmental cost and poor surface modifiability hinder the broader adoption of contact-electro-chemistry (CE-Chemistry). Here, we report a low-cost and tunable dielectric alternative based on silicon powder, surface-functionalized with fluorinated alkyl chains to mimic the interfacial properties of conventional fluoropolymers. Fluorinated silicon powders (F-Si) were synthesized via a mild self-assembly approach using 1H,1H,2H,2H-perfluorodecyltriethoxysilane. The resulting F-Si powders exhibited a 30-fold enhancement in methyl orange degradation efficiency compared to unmodified silicon, and a 4-fold improvement in phenol degradation relative to size-matched FEP powder. In contrast, aggressive fluorination via piranha-assisted pretreatment (P-F-Si) induced particle aggregation and loss of CE reactivity, highlighting the importance of controlled surface engineering. Furthermore, CE-Chemistry enabled the first noble-metal-free oxidation of I^- to I₃ ^-, establishing a low-energy, cost-effective paradigm for catalytic iodine conversion. Together, these advances provide a sustainable materials design framework for CE-Chemistry, with broad implications for scalable, green chemical transformation technologies.