Ti4O7 nanoparticles composited with polypyrrole (PPy)/activated carbon foam - \(ACF) for enhancing its service life significantly in SBF

摘要

Polypyrrole (PPy) possess excellent electrochemical properties, suitable strain-regulating mechanical property and flexibility, and low electrode/solution interface impedance, which is often used in sensing, corrosion protection, drug - carrying release, and have demonstrated promising application for implants [1]. However, the inherent defect of polypyrrole is easy degradation, especially in solution, it is susceptible to chemical degradation caused by nucleophilic attack of OH-, Cl-and H2O and electrochemical degradation caused by the presence of a differential protocell of dissolved oxygen concentration, which limits its further application in biomedical field[2]. It has been demonstrated that the stability of PPy can be improved by compositing with carbon materials and metal oxides, and Ti 4O7 can bind to various sulfur elements according to density flooding theory (DFT) calculations [3], so polypyrrole coatings doped with modified Ti4O7 particles were prepared on the surface of three-dimensional open-cell activated foam carbon electrodes using electrochemical deposition, and Ti4O7 particles were bound to S in sodium p-toluenesulfonate through S-O-Ti bonds, and then further bind to PPy through electrostatic interactions, making the composite coating structure more dense and difficult for corrosive ions to exchange with counterions. In this paper, the corrosion degradation process of Ti 4O7+PPy/C complex in human simulation body liquid (SBF) for 90 days was investigated. Both cyclic voltammograms and electrochemical impedance spectra show that the complex still maintains a good electrochemical activity after 90 days of immersion experiments, and SEM maps show that a great number of Ti 4O7 particles as well as typical PPy morphology still exist on the surface of the complex. Therefore, this paper provides an effective way to improve the chemical stability of polypyrrole. Fig.1. (a) CVs, (b) Nyquist plots, and (c,d) Bode plots of (Ti4O7+PPy)/ACF after immersion in SBF solution for different times. Fig.2. SEM morphologies of (a) PPy/ACF, (c) Ti4O7+PPy/ACF, (c~d) EDX mappings of Ti4O7+PPy/ACF, and (e~f) after 90 days of soaking.