Electrodeposition of conducting coating on insulator substrate
Tan, Alvin Wei Ming
Date of Issue2017-05-17
School of Materials Science and Engineering
Electrochemical deposition is widely employed for active or functional coatings on conductive substrates. The need of conductive substrate restricts the use of electrodeposition on insulator surfaces with the exception of electroless deposition which is generally used for deposition of metals and lacks in-situ control. The emergence of deformable and wearable electronics device has prompted the search for coating methods on foldable and flexible surfaces which may not be conductive, in order to meet the rising demand of the modern wearable electronic devices requirements. Under specific non-equilibrium conditions, space charge dominated electrodeposition has been earlier reported on insulators, with prior 2 nm thick discontinuous gold coating. In this work, we employ pulse electrodeposition (short alternating pulse current or potential) to provide high electric field in proximity configuration to enable the space charge dominated mechanism for electrodeposition on insulator (EDI) without metal precoating. A continuous nanofibrous polyaniline film was successfully coated onto insulating cellulose paper, glass, polyester and PET. This approach does not require the use of buffer or catalyst and it possesses potential for possible large scale fabrication. The samples were characterized using Scanning Electron Microscopy, Raman Spectroscopy and Fourier transform infrared spectroscopy. To demonstrate the vast potential of this EDI method, the polyaniline coated on insulator substrates using EDI were fabricated into functional gas sensors that exhibit quick response to low concentration of N02 (5 ppm).