Rucl3

The pristine CNFs are prepared by electrospinning an 8 wt% polyacrylonitrile (PAN) in dimethylformamide (DMF) solution to receive nanofibers to receive polymer nanofibers. The nanofibers are then oxidized in air at 533 K for 5 h and carbonized at 1073 K for another 2 h to become CNFs. In order to synthesize metallic nanoparticles, a precursor solution is prepared by dissolving certain amount of salt precursor(s) (H₂PtCl₆, RuCl₃, PdCl₂, NiCl₂ (Sigma Aldrich)) in ethanol. The CNFs are thereafter soaked in the salt-ethanol solution for one hour and dried in air to achieve the salt-coated carbon nanofibers (S-CNFs). The ex situ sample was prepared through Joule heating of salt loaded CNF film (schematically shows in Fig. S16), where the CNF film image can be seen from Fig. S17 and the loading amount of Pt salt precursor was 0.25 μmol/cm².

Analytical reagents used in the experiments were bought from Sigma Aldrich: Al₂(SO₄)₃·18H₂O, sodium tartrate, CO(NH₂)₂, NH₄NO₃, Ni(NO₃)₂·6H₂O, RuCl₃, ethanol, 4-nitrostyrene (4-NS), 4-aminostyrene, 4-nitroethylbenzene, 4-aminoethylbenzene, and nitrobenzene, styrene. Purified water was adopted in all the experiments.

The electrode with nominal composition Ti/RuO₂-TiO₂-SnO₂ (Ru:Ti:Sn 50:40:10 atom. %) were prepared through thermal decomposition (T_calcination: 450 °C). The polymeric film subjected to high temperatures for the organic material is eliminated to obtain the oxide coating. Precursor solutions were prepared at the presence of 0.1 mol of RuCl₃, C₁₂H₂₈O₄Ti, and SnCl₄ (all Sigma-Aldrich, St. Louis, MO, USA), in ethanol. After, the precursor mixtures were dissolved at the presence of the 4.0 mol acid citric and 16.0 mol ethylene glycol (all Sigma-Aldrich) and heated at T = 90 °C to occurred esterification process. Before the deposition of oxide films, the plate of titanium (2.0 cm²) used as a substrate was sandblasted (105–210 µm) in order to improve the adherence of metal oxides. After that, the surface was degreased and submitted to chemical activation in concentrated HCl (20% v/v) for 30 min, washed in a solution of oxalic acid (10%) for 20 min, and rinsed with ultrapure water. Afterwards, the electrode was dried at low temperature. The precursor mixtures were deposited on the pretreated Ti substrate. The deposited coatings were thermally treated in the oven at 130 °C for 10 min, then again at 450 °C for 5 min. Upon reaching the desired mass, the electrode was calcined at 450 °C for 1 h.

At first, the graphite carbon nitride (g-C₃N₄) nanosheets were prepared via a direct pyrolysis method. In a typical process, 10 g of urea (Sigma-Aldrich, ≥99% purity) were heated to 600 °C with a ramp rate of 5 °C min⁻¹ and maintained for 2 h in air atmosphere, and then naturally cooled to room temperature to obtain the yellow powders. The phosphor-decorated carbon nitride (PCN) were synthesized as follows: 300 mg as-obtained g-C₃N₄ nanosheets were mixed with 1.5 g NaH₂PO₂·H₂O (Sigma-Aldrich, ≥99% purity, 5:1) sufficiently through grinding over 30 minutes. Then, the mixture was heated to 300 °C with a heating rate of 2 °C min⁻¹ and maintained for 2 h in argon atmosphere. As for Ru-N-C, 200 mg PCN were dispersed in a flask with 60 mL deionized water under continuous sonication for 30 mins and transformed into oil bath. Then, 1.0 mL of RuCl₃ (Sigma-Aldrich, ≥99% purity) aqueous solution (10 mg mL⁻¹) was dropped into the homogeneous PCN aqueous through microinjection pump and keeping stirring at 70 °C for 5 h. The mixture were further dried via rotary dryer and transferred in the tube furnace and heated at 300 °C for 2 h in argon atmosphere. The obtained powders were ultrasonicated and washed several times with deionized water and ethanol, finally dried under vacuum overnight at 60 °C.

An asymmetric block copolymer, polystyrene-block-poly (methyl methacrylate) (PS-b-PMMA, molecular weight: PS/PMMA-46k/21k, P2400-SMMA), was purchased from Polymer Source Inc. (Dorval, QC, Canada). The iron source for electron beam evaporation (purity: 99.95%) was purchased from Thifine (Incheon, Korea). KMnO₄ and RuCl₃ for the synthesis of MnO_x and RuO_x nanoparticles were purchased from Sigma Aldrich.

Ni foam was purchased from Shenzhen Green and Creative Environmental Science and Technology Co. Ltd. KOH and absolute alcohol were purchased from Beijing Chemical Corp. Ni(NO₃)₂·6H₂O was purchased from Fuchen Chemical Reagents Factory. VCl₃ was purchased from the Energy Chemical. Urea and IrCl₃·H₂O were purchased from Aladdin. Pt/C (20 wt% Pt on Vulcan XC-72R), RuCl₃, and Nafion (5 wt%) were purchased from Sigma-Aldrich. All chemicals were used as received without further purification. The water used throughout all experiments was purified through a Millipore system.