Ircl3 3h2o

Plain carbon fibre cloth (0.35 mm thickness, E-TEK) was used as the substrate for the catalysts. The carbon cloth electrode (1 × 1 cm²) was sonicated in diluted hydrochloric acid, deionized water, and isopropanol for 1 min respectively. PtIr/C catalysts (20 wt% of metals loading) were prepared by the borohydride reduction process^{88 (link)} using K₂PtCl₆ (Pt 39.6%, Thermo Scientific™), IrCl₃ ∙ 3H₂O (53–56% Ir, Thermo Scientific™) and Vulcan XC72 carbon black (Cabot) as precursors. The atomic ratio of Pt:Ir is 50:50. The catalyst ink was made up of 80 mg PtIr/C powder, 500 μL isopropanol and 145 μL 5 wt% Nafion solution (Sigma Aldrich). The ink slurry was ultrasonicated for 1 h and then brushed onto the pre-treated carbon cloth. The electrode was dried in an oven at 80 °C. The loading of PtIr was about 1.2 mg cm^-2. The Pt/C electrode (20 wt% Pt on carbon black, Alfa Aesar) was prepared in the same way and the loading of Pt was about 1.3 mg cm^-2.

Precursor salts of Ni(NO₃)₂•6H₂O (99%), Mg(NO₃)₂•6H₂O (99 + %), Al(NO₃)₃•9H₂O (99 + %), ZrO(NO₃)₂•H₂O (99.5%), Co(NO₃)₂•6H₂O (99 + %), Ga(NO₃)₃•H₂O (99.99%), Ce(NO₃)₃•6H₂O (99.5%), and Cr(NO₃)₃•9H₂O (99%) were purchased from Acros Organics; In(NO₃)₃•H₂O (99.99%), Nd(NO₃)₃•6H₂O (99.9%), Er(NO₃)₃•5H₂O (99.9%), and Pt(NO₃)₄ solution (Pt 15 w/w) were purchased from Alfa Asear; Fe(NO₃)₃•9H₂O was purchased from Fisher Chemical; Zn(NO₃)₂•6H₂O (98%) was purchased from Sigma Aldrich; Pd(NO₃)₂•H₂O (99.8%, Pd 39% min) and IrCl₃•3H₂O (Ir 53–56%) were purchased from Thermo Scientific. NaOH pellets were purchased from Sigma Aldrich. Hexadecyltrimethylammonium bromide (CTAB, 99 + %) and HCl (37%) were purchased from Acros Organics. Ethanol (200 proof) was obtained from Decon Labs, Inc.