Controlling Physical and Chemical Bonding of Polypyrrole to Boron Doped Diamond by Surface Termination

Abstract

To elucidate and to control polypyrrole (PPy) attachment to diamond we electrochemically grow PPy layers on hydrogen- and oxygen-terminated boron doped diamonds (BDD). Atomic force microscopy (AFM) shows that the PPy layers have similar morphology (15 nm features) and thickness (> 5 nm) on H- and O-BDD. To resolve type of PPy-diamond bonding, scanning electron microscopy (SEM) is used to compare intensity of secondary electron emission from original BDD regions and regions where PPy was grown and removed by AFM tip. The intensity on O-BDD remains unchanged. The intensity on H-BDD is lower than where the PPy was removed. This indicates chemical bonding (covalent) of PPy to H-BDD and physisorption (non-covalent) of PPy on O-BDD. This conclusion is corroborated by Kelvin force microscopy and by a model of energetic bands and electron affinity on the diamond surface.