Acid-Basic Site Detection and Mapping on Solid Surfaces at the Nanoscale, by Kelvin Force Microscopy (KFM)

摘要

Nanoscale electric potential patterns of acid and basic solid surfaces is modified under variable relative humidity, as determined by using Kelvin force microscopy (KFM). The electrostatic potential on acid surfaces becomes more negative as the water vapor pressure increases, while it becomes more positive on basic solids. These results verify the following hypothesis: OH- or H~+ ions associated with atmospheric water ion clusters are selectively adsorbed on solid surfaces, depending on the respective Br?nsted acid or base character. KFM under variable humidity is thus a rigorous but convenient alternative to determine acid-base character of solid surfaces at the nanoscale, thus contributing to detailed knowledge of particulate matter, which is currently inaccessible to any other method.