Water dissociation on a gold cluster: the effect of carbon nanostructures as a substrate

Abstract

Water dissociation at the gold interface can be of fundamental importance in areas like catalysis and electrochemistry. In recent years, gold nanocluster based catalysts have opened up new avenues of research. In the present computational study, we have investigated the catalytic activity of a pristine gold cluster Au₈ as well as the cluster supported on substrates such as defective graphene and a carbon nanotube (CNT) for the dissociation of a water molecule. Our results reveal that the dissociation of water on the pristine cluster can be associated with higher barrier height while the process becomes more facile with the carbon nanostructures as substrates, especially the CNT. For the Au₈–CNT system, we have demonstrated the dissociation of a second water molecule is associated with a lower barrier than the first one and this leads to the generation of molecular hydrogen. We attribute the strong charging effects of the cluster in case of the Au₈–CNT system as the possible driving factor for this process. The CNT–Au system is, thus, proposed as a robust nanostructure for the water dissociation process. Although gold cluster based catalysis has been well explored in terms of their favorable role in other reactions, our report comes as a first report towards the demonstration of catalytic activity of nanoscale gold for the water dissociation process.