Osmium 3 chloride

Osmium(III) chloride (OsCl₃, 99.9%), sodium borohydride (NaBH₄, 99.8%), osmium (Os, 99.9%), osmium tetroxide (OsO₄, ≥98.0%), chloroplatinic acid hexahydrate (H₂PtCl₆·6H₂O, ≥37.50% Pt basis), silver chloride (AgCl, 99%), ruthenium(III) chloride hydrate (RuCl₃·xH₂O, 99.98%) and hydrochloric acid (HCl, 37%) were purchased from Sigma-Aldrich. Gold chloride trihydrate (HAuCl₄·3H₂O, ≥99.9%), potassium hexachlororhodate(III) (K₃RhCl₆, Rh≥23.3%), iridium chloride (IrCl₃, 99.8%) and palladium chloride (PdCl₂, 99.999%) were purchased from Aladdin (Shanghai, China).

Platinum(II) acetylacetonate (Pt(acac)₂, 97%), potassium tetrachloroplatinate(II) (K₂PtCl₄, 98%), ruthenium(III) chloride (RuCl₃, Ru content 45%–55%), osmium(III) chloride (OsCl₃, 99.9%), and iridium(III) acetylacetonate (Ir(acac)₃, 97%) from Sigma-Aldrich, oleylamine (95.4%, primary amine) from J&K Scientific, silver nitrate (AgNO₃, 99%), aqueous HClO₄ solution (70%, ACS reagent), and Nafion 117 solution (5% in a mixture of lower aliphatic alcohols and water) from Aladdin Reagents, sodium chloride (NaCl, analytical grade) from Xilong Chemical Co., Ltd., acetic acid (C₂H₄O₂, analytical grade), methanol (99%), and toluene (99.5%) from Beijing Chemical Works, and Vulcan XC-72 carbon powders (XC-72C) with BET surface area of 250 m² g⁻¹ and average particle size of ca. 40 nm from Cabot Corporation, were used as received. All glassware and Teflon-coated magnetic stir bars were cleaned with aqua regia, followed by copious washing with de-ionized water before drying in an oven.