Gold nano-sheets intercalated between graphene planes

The lamellar structure of graphite is known for allowing intercalation of numerous chemical species between its graphene planes. Considering the intercalation of the electron donors, some pure metals, several metallic alloys and even electronegative elements associated with electropositive metal lead to binary or ternary graphite intercalation compounds. In all cases, the presence of an alkali metal is essential in order to open the van der Waals's intervals, what is performed in this study dealing with the graphite-potassium-gold original system. Gold is very particular since it is a true metal but strongly electronegative too. Associated with potassium, it becomes able to intercalate easily into graphite, leading to a first stage graphite-potassium-gold compound. This study displays the best synthesis conditions to prepare this pure ternary compound. The study of its 00l reflections leads to determine the repeat distance (1311 pm) with a five-layered stacking sequence of the intercalated sheet along the c-axis. Two potassium mono-layers surround a three-layered gold nanosheet, so that the c-axis expansion reaches 237%. A chemical formula K1.30Au1.50C4, namely 0.7 metallic atom for one carbon atom, has been determined for this compound. A discussion concerning the charge transfer between graphene planes, potassium and gold atoms is also proposed.