Ab initio investigation of the effects of B-doping on the adsorption of H2O, H2 and O2 molecules at diamond surfaces

Abstract

Boron doped diamond is extensively studied for its use in tribological and electrochemical applications due to its remarkable physical and chemical properties. However, ambient conditions play a major role to its macroscopically observed behavior. In this study, the fundamental interactions between the low Miller index (001), (110) and (111) B-doped diamond surfaces with H2O, H2 and O2 molecules, which are commonly present in ambient air and commonly involved in electrochemical reactions, are investi-gated by means of ab initio simulations. The results are presented in close comparison with previous studies on undoped diamond surfaces to reveal the impact of B on the adsorption properties. It is demonstrated that the B dopant is preferably incorporated on the topmost carbon layer and enhances the physisorption of H2O by forming a dative bond with O, while, in some cases, it can weaken the ad-sorption of O2, compared to the undoped diamond. Moreover, a noticeable displacement of the surface atoms attached to the fragment of the dissociated H2O and O2 molecules was observed, which can be associated to the first stage of wear at the atomistic level. These qualitative and quantitative results aim to provide useful insight towards the development of improved protective coatings and electrochemical devices.