Potassium hexachloroplatinate

Potassium hexachloroplatinate (98% K₂PtCl₆), Ni II acetyleneacetonate (Ni(acac)₂ 95%), oleylamine (OAm 70%), ethanol (99.5%), and ethylene glycol (99%) were purchased from Sigma–Aldrich Co., Ltd. The Pt/C catalyst was purchased from Premetek (40% Pt on Vulcan XC 72).

Ti sheet (0.25 mm thick, 99.7 % purity), ethylene glycol (analytical grade), and ammonium fluoride (analytical grade) were purchased from Sigma‐Aldrich. The DC power supply used to prepare titania nanotubes was by Keithley Instruments (Model 2200–72‐1DC). Calcium hydride (CaH₂, ≥97.0 % powder) and potassium hexachloroplatinate (K₂PtCl₆, ≥99.9 % trace metals basis) were supplied from Sigma Aldrich, perchloric acid (HClO₄, 70 %) from Merck, and hydrochloric acid (HCl, 37 % for laboratory use) and nitric acid (HNO₃, 65 %) from ChemLab.

Large flake natural graphite was purchased from NGS Naturgraphit GmbH with a purity of 99.9% C and flake size of 2.5 mm, stated by the manufacturer. Natural flake graphite (NFG) was obtained from Graphexel Ltd (grade: 2369). Graphite nanoplatelets (Elicarb Materials Grade Graphene Powder SP8082) were supplied by Thomas Swan, with a typical lateral size of 1–5 μm and carbon content of 98%. Few-layer graphene (FLG) was obtained from CamGraph nanosystems UK, with a carbon purity >99.5% and an average lateral size of 0.5 μm. Graphite nanofibers (GNF) were supplied by Future Carbon GmbH (batch no. A09-122.123). All the graphite starting materials were used without any further purification, though dried thoroughly as described below. Tetrahydrofuran, dried in-house in a solvent-drying tower packed with alumina, and dodecyl bromide (Sigma-Aldrich) were degassed via a freeze–pump–thaw method then further dried over 20 vol% 4 Å activated molecular sieves. Naphthalene (99%, Sigma-Aldrich) was dried under vacuum in the presence of phosphorus pentoxide before use. Sodium (99.95%, ingot) and potassium hexachloroplatinate were purchased from Sigma-Aldrich and used as received. 5-Monobromomethyl-5′-methyl-2,2′-bipyridine (1) was synthesised according to a procedure described in literature.^{12 (link)}