Potassium hydroxide

Cobalt (II) nitrate hexahydrate (Co(NO₃)₂·6H₂O, ≥98.5%), sodium hydroxide (NaOH, ≥96.0%), sodium hypochlorite (NaOCl, active Cl ≥96.0%), potassium hydroxide (KOH, ≥ 85.0%), active carbon, alcohol (≥99.7%), and Nafion (15–20%) were purchased from Shanghai Chemical Reagent Company. Iridium (IV) chloride hydrate (IrCl₄·xH₂O, Ir ≥56.0%) was purchased from Aladdin. All the other chemicals were of analytical grade and used as received without further purification. All aqueous solutions were prepared using deionized water with a resistivity of 18.2 MΩ cm⁻¹.

Iridium (IV) chloride hydrate (IrCl₄·xH₂O), sodium tetrachloropalladate(II) (Na₂PdCl₄), and gold (III) chloride hydrate (HAuCl₄·xH₂O) were purchased from Aladdin. Sodium hexachlororhodate (III) dodecahydrate (Na₃RhCl₆·12H₂O) was purchased from Alfa Aesar. Commercial Pt/C catalyst (20 wt%, Pt nanoparticles with the size ranging from 2 to 5 nm) was purchased from Johnson Matthey Corporation. Potassium hydroxide (KOH), sodium chloride (NaCl), hexamethylenetetramine, 2-methylimidazole, hexaammonium heptamolybdate tetrahydrate ((NH₄)₆Mo₇O₂₄·4H₂O), ethanol, methanol, thiourea, ethanolamine, sodium hydroxide (NaOH), selenium powder (Se), hydrazine, dimethylformamide (DMF), vanadium (III) chloride (VCl₃), chromium (III) chloride (CrCl₃), manganese (II) chloride tetrahydrate (MnCl₂·4H₂O), ferric (III) chloride (FeCl₃), cobalt (II) chloride hexahydrate (CoCl₂·6H₂O), nickel (II) chloride (NiCl₂), copper (II) chloride (CuCl₂), zinc (II) nitrate hexahydrate (Zn(NO₃)₂·6H₂O), ruthenium (III) chloride (RuCl₃), silver nitrate (AgNO₃), chloroplatinic (II) acid (H₂PtCl₄), and iridium (IV) oxide (IrO₂) were purchased from Shanghai Chemical Reagent Company. All the other chemicals were of analytical grade and used without further purification. All aqueous solutions were prepared using deionized water with a resistivity of 18.2 MΩ cm⁻¹.