Superhydrophilicity and Antifouling Behavior in Electrochemically Oxidized Nanocrystalline Pseudographite

Abstract

Electrochemical oxidation of GUITAR (pseudoGraphite from the University of Idaho Thermolyzed Asphalt Reaction) produces a surface that exhibits superhydrophilic properties. This surface contains 20.7% relative oxygen abundance, giving it a heightened affinity for water relative to the pristine material. Scanning electron and atomic force micrographs reveal spherical, bubble-like structures on GUITAR, indicating a higher surface roughness (Rq = 300-400 nm) over the predominantly smooth titanium substrate (Rq = 94.5 nm). Combining an intrinsic affinity toward water with a heightened surface roughness produces a material with an apparent water contact angle of 0°. The synergistic effects of a superhydrophilic surface that can function as an electrode result in an electrocatalyst material that is highly resistant to fouling. When stored in water, oxidized GUITAR (Ox-GUITAR) completely resists fouling by volatile organic compounds for the duration of testing (72 h). When fouled directly with a drop of oil, the residue can be removed using a simple water rinse. The removal of oil residues from carbon surfaces is typically not possible without the use of solvents, surfactants, or mechanical exfoliation. This combination of properties opens Ox-GUITAR to a broad array of possible applications, such as implantable electrodes, field sensors, or water-quality monitoring.