Signature of Proton-Hole Transfer in Hydrogen-Bonded Solids at 10 K

Although proton transport in water ice is well understood, proton-hole transfer (PHT) involving proton abstraction by anions remains less explored. This study investigates PHT in HS and NH solids at low temperatures, aiming to determine whether these solids exhibit negative charge transport similar to that in ice. In HS and NH solids at 10 K, surface HS and NH anions in hydrogen-bonded systems trigger negative current flow, providing a clear signature of PHT. This negative current is controlled by electron flow and 193 nm ultraviolet irradiation, which generates HS and NH anions on the solid surfaces. In bilayer HS/HO and NH/HO solids, a significant negative current is observed only in the NH/HO solid, which is attributed to the exothermic proton abstraction by NH from HO at the bilayer interface, a process not available for HS on ice. This study is the first to demonstrate PHT-induced electrochemical behavior in hydrogen-bonded solids other than ice.