Dynamic Optical Visualization of Proton Transport Pathways at Water–Solid Interfaces

Abstract

Probing proton transport is of vital importance for understanding cellular transport, surface catalysis and fuel cells.Conventional proton transport measurements rely on the use of electrochemical conductivity and do not allow for the direct visualization of proton transport pathways. The development of novel experimental techniques to spatiotemporally resolve proton transport is in high demand. Here,b uilding upon the general conversion of aqueous proton flux into spatially resolved fluorescence signals,w eo ptically visualize proton transport through nanopores and along hydrophilic interfaces.W eo bserved that the fluorescence intensity increased at negative voltage due to lateral transport. Thanks to the temporal resolution of optical imaging,o ur technique further empowers the analysis of proton transport dynamics.

Observation of Potential-Induced Hydration on the Surface of Ceramic Proton Conductors Using In Situ Near-Ambient Pressure X-ray Photoelectron Spectroscopy

“…Many researchers have studied the effects of material structure and composition on proton transport in ceramics. − Investigating the surface chemistry between solid and ambient gas interface can lead to better understanding of the ion site activity and proton and oxygen transport. − Encouraging results have established that in different environment, proton transport properties are strongly influenced by hydration-induced changes in surface chemistry. − Stub et al showed that different structures of the adsorbed water layer on oxide surface affect the activation energy for proton transport. To study the mechanism of surface hydration at relevant conditions, such as temperature and atmosphere, in situ spectroscopic probes are highly effective approaches. − In particular, in situ X-ray photoelectron spectroscopy (XPS) has provided inspiring results on proton conductors: our previous work showed the V O •• filling upon hydration is associated with charge redistribution between ions; Jarry et al , observed that surface composition affects OH – formation under different conditions for BaCe x Zr 0.9‑x Y 0.1 O 2.95 thin films.…”