The surface chemistry of diamond

A surface chemical study of the diamond/water interface has been made which involved measurement of the electrokinetic, acid-base and wetting properties of diamond. The results obtained are considered in relation to the different groups present on the diamond surface.The groups on the surface of diamond include epoxide, carbonyl, carboxylic and hydroxyl. Less than 10% of the surface carbon atoms are linked to an acidic and/or carbonyl group. During ageing in water the number of moderately acidic groups does not apparently change although the electrophoretic mobility becomes more negative. The presence of a p positive site is suggested to account for the apparent inconsistency between the electrokinetic and acid-base properties.Freshly cleaned hydrophobic diamonds and diamond powder become hydrophilic on exposure to water. Hydration of ionic and non-ionic polar sites and an increase in the number of hydroxyl sites could account for these observations.