Iridium 4 oxide

Melamine (99%, CAS no. 108-78-1), l-cysteine (≥98%, CAS no. 52-90-4), iridium(III) chloride hydrate (99.9% trace metals basis, CAS no. 14996-61-3), sodium phosphate dibasic (≥99.0%, CAS no. 7558-79-4), sodium phosphate monobasic (≥99.0%, CAS no. 7558-80-7), perchloric acid (70%, CAS no. 7601-90-3), potassium hydroxide (pellets, 99.99% trace metals basis, CAS no. 1310-58-3), methanol (≥99.9%, CAS no. 67-56-1), platinum on Vulcan XC72 powder (20 wt.% loading), iridium on Vulcan XC72 powder (20 wt.% loading), iridium(IV) oxide (99.9% trace metals basis, CAS no. 12030-49-8), isopropanol (99.5%, CAS No. 67-63-0) and nafion 117 solution (~5% in a mixture of lower aliphatic alcohols and water) were purchased from Sigma-Aldrich and used without further purification.

Ammonium molybdate tetrahydrate ((NH₄)₆Mo₇O₂₄·4H₂O, 90%), cobalt nitrate hexahydrate (Co(NO₃)₂·6H₂O, 99.9%), potassium hydroxide (KOH, 85%), iridium(IV) oxide (IrO₂, 99.9% metal basis) and Nafion (5 wt% within a blend of low aliphatic alcohols and water) were obtained from Sigma-Aldrich (St. Louis, MO, USA). 2-Methylimidazole (C₄H₆N₂, 99%) was purchased from Acros Organics (Antwerp, Belgium). Analytical grade methanol, ethanol and isopropanol were obtained from different sources. Milli-Q water was produced using an Elga Purelab flex. All chemicals were used as received.