Proton transport over nanoparticle surface in insulating nanoparticle film-based humidity sensor

Abstract

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