Scanning Probe Microscopy Analysis of the Adsorption of Volatile Organic Compounds on Carbonaceous Films with Microcolumnar Structure

Adsorption interactions between adsorbate of volatile organic compound (VOC) and adsorbent film were investigated using Kelvin probe force microscopy and differential force microscopy. An adsorbent film with carbonaceous columnar structures was prepared using radio-frequency sputtering of pectin. The VOCs were identified by their dielectric constants, polarizabilities, and refractive indices. Polar VOCs enhanced the interaction forces and negative surface potentials of the adsorbent films. The negatively charged potential showed thermal drift, which is stronger for polar VOCs. Thermal release of electrons trapped in the surface states by band bending was enhanced by the adsorption of polar species. Activation energy is closely correlated with the negative shift of the surface potential. Quantitative structure property relationship analyses suggest that the local charges of adsorbate VOCs are crucial for these surface properties: surface potential, surface interaction force, and adsorption amount. [DOI: 10.1380/ejssnt.2015.195]