Proton transport over nanoparticle surface in insulating nanoparticle film-based humidity sensor
Abstract We study a proton transport on the surface of insulating nanoparticles for humidity sensors. We use the approach to reveal proton transfer mechanisms in humidity sensitive materials. Hydrophilic and hydrophobic ligand-terminated silica nanoparticle films are adopted for evaluating temperature dependence of the ion conductivity. According to the activation energy of the conductivity, we explain the Grotthuss (H+ transfer) and vehicular (H3O+ transfer) mechanisms are mainly dominant on hydrophilic (-OH terminated) and hydrophobic (acrylate terminated) surface of nanoparticles, respectively. This investigation gives us a clue to understand a proton transfer mechanism in solution-processed humidity-sensitive materials such as oxide nanomaterials.