Influence of Boron-Doped Diamond Surface Termination on the Characteristics of Titanium Dioxide Anodically Deposited in the Presence of a Surfactant

Boron-doped diamond (BDD) films were subjected to cathodic or anodic pre-treatments to achieve hydrogen-terminated (BDD-H) or oxygen-terminated (BDD-O) surfaces and then used as supports for surfactant-assisted anodic deposition of titanium oxide. Cyclic voltammetry and EIS experiments have shown that, unlike BDD-O case, at the BDD-H surface a stable layer of sodium dodecyl sulfate (SDS) is formed, which hinders TiO2 overall deposition process, as demonstrated by linear sweep voltammetry. SEM measurements revealed that this sluggish process leads to a better uniformity and to a higher roughness of the oxide coatings. When deposited on BDD-H, TiO2 also exhibited a light to dark current ratio with ca. 28% higher than that enabled by the use of a BDD-O substrate, indicating a better efficiency of charge carrier separation.