Aqueous hclo4 solution

The following materials were used as received: potassium tetrachloroplatinate(II) (K₂PtCl₄; 98%), silver nitrate (AgNO₃; 99%), gold(III) chloride trihydrate [HAuCl₄·3H₂O; ACS reagent; 49.0% Au basis), palladium(II) acetylacetonate [Pd(acac)₂; 99%], acetic acid (CH₃COOH; 98%), sulfur powder (S; chemical grade), and oleylamine (primary amine; 95.4%) from J&K Scientific; aqueous HClO₄ solution (ACS reagent; 70%) and Nafion 117 solution (5% in a mixture of lower aliphatic alcohols and water) from Aladdin Reagents; ethanol (99%), methanol (99%), and toluene (99.5%) from Beijing Chemical Works; and Vulcan XC 72 carbon powders (XC 72C) with a BET (Brunauer–Emmett–Teller) surface area of ca. 250 m² g⁻¹ and average particle sizes of ca. 40 to 50 nm from Cabot Corporation. Commercial Pd/C and Pt/C catalysts were purchased from Johnson Matthey. All glassware and Teflon-coated magnetic stir bars were cleaned with aqua regia, followed by copious washing with deionized water before drying in an oven.

Potassium tetrachloroplatinate(II) (K₂PtCl₄, 98%), silver nitrate (AgNO₃, 99%), gold(III) chloride trihydrate (HAuCl₄·3H₂O, ACS reagent, >49.0% Au basis), sulfur powder (S, chemical grade), and dodecylamine (DDA, 98%) from Aldrich, oleylamine (95.4%, primary amine) from J&K Scientific, aqueous HClO₄ solution (70%, ACS reagent) and Nafion 117 solution (5% in a mixture of lower aliphatic alcohols and water) from Aladdin Reagents, ethanol (99%), methanol (99%) and toluene (99.5%) from Beijing Chemical Works, and Vulcan XC-72 carbon powders (XC-72C, BET surface area = 250 m² g⁻¹ and average particle size = 40 ~ 50 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.