Preparation, structure and reduction of graphite intercalation compounds with hexachloroplatinic acid

Electrochemical oxidation and exchange intercalation, have been used for the production of graphite intercalation compounds (GICs) with hexachloroplatinic acid. Ternary GICs H₂PtCl₆-HNO₃-graphite and H₂PtCl₆-H₂SO₄-graphite have been synthesized by the incomplete exchange reaction between the parent HNO₃ and H₂SO₄ GICs and hexachloroplatinic acid. Irrespective of the precursor GIC stage, stage-2 GIC with H₂PtCl₆ has been obtained. Attempted synthesis of the single-phase stage-2 GIC via the electrochemical oxidation of graphite in H₂PtCl₆ solutions failed since mixtures of the target products with pure graphite have resulted in all cases. The structure and properties of the samples obtained have been examined by XRD, SEM, TG-DTG, TG coupled with FTIR and EXAFS-XANES. GIC samples were preheated to 200 °C to produce exfoliation (caused by deintercalation of nitric acid), and reduced either with boiling 5% aqueous formaldehyde or hydrogen. This approach gives rise to exfoliated graphite material with platinum nanoclusters distributed on the surface. In contrast to the most other work particles with open surfaces were obtained.