Synthesis of Pt/Fe2O3 Catalysts via Rapid Thermal Treatment

The FeOOH support was prepared by a precipitation method. Briefly, 4 g ammonium carbonate ((NH₄)₂CO₃) was put into 60 mL deionized water and stirred at 50 °C until it was completely dissolved. Then, 20 mL of an aqueous solution of ferric nitrate (Fe(NO₃)₃, 1 mol L⁻¹) was added and stirred for 3 h. After aging for 3 h at 50 °C, the solid was filtrated and washed with deionized water and finally dried at 60 °C for 12 h. The Brunauer–Emmett–Teller (BET) surface area of the as-prepared FeOOH support was 266 m² g⁻¹.
The Pt-en precursor was prepared by mixing 10 mL of an aqueous solution of chloroplatinic acid (H₂PtCl₆, 5 mmol L⁻¹) with 1 mL ethanediamine (en) at room temperature. Then, this Pt-en precursor was added to a suspension of the FeOOH support (1 g in 10 mL deionized water). After stirring for 4 h, the solid was filtrated and washed with deionized water and finally dried at 60 °C for 12 h to obtain the Pt₁/FeOOH-RT sample.
The series of Pt₁/Fe₂O₃-T catalysts were prepared by RTT of Pt₁/FeOOH-RT in He at the specified temperature for 1 min. Briefly, the Pt₁/FeOOH-RT sample was put into a quartz tube, which was then inserted into a tube furnace pre-heated to the specified temperature. Under the He flow (30 mL min⁻¹) the sample was kept at that temperature for 1 min, and then the quartz tube was quickly taken out and rapidly cooled down to RT (Supplementary Fig. 1). The Pt/Fe₂O₃-600-10 min NP catalyst was prepared by the same method, except for keeping at 600 °C for 10 min.
More sample preparation details are described in the Supplementary Methods section.