Vulcan xc 72r

The oxidation of commercial carbon supports Black Pearls^® 2000 (BP) and Vulcan^® XC72R (V), both provided by Cabot (Boston, MA, USA), was carried out according to Schmies et al. [31 (link)]. A total of 2 g of carbon black was stirred in 200 mL of concentrated HNO₃ (65 wt.%) purchased from Carl Roth (Karlsruhe, Germany) for 5 h at 90 °C, followed by filtration and washing with ultrapure water until neutral pH and drying in vacuum oven at room temperature for 24 h.

Pt nanoparticle synthesis was performed according to the protocol reported by Liu et al.17 Briefly, the synthesis is initiated by dissolving 0.25 mmol Pt(acac)₂ (Acros Organic) and 1.50 mmol 1,2-tetradecanediol (90 %, Sigma Aldrich) in 20 mL dioctyl ether (99 %, Sigma Aldrich) under Ar atmosphere, followed by heating to 110 °C at a rate of 5 °C min⁻¹ under stirring. OA (4.2 mmol; 70 %, Sigma Aldrich) was added drop-wise to the clear, yellow solution over the course of 2 min. The solution was further heated to 215 °C, and left to stir for 1 h before cooling to 50 °C. The dark brown particle dispersion was added to a glass vial containing 10 mL MeOH, and sonicated for 5 min. Nanoparticles were precipitated by centrifugation, and re-dispersed in hexane. All high-purity reagents were used as received. To prepare the carbon-supported catalyst (Pt/C), Vulcan XC-72R (Cabot Corp) was added to a colloidal Pt nanoparticle dispersion, and sonicated for 2 h. The solution turned clear, indicating complete deposition of nanoparticles onto the carbon support. Hexane was removed under a stream of argon to yield the dry Pt/C catalyst powder.
A variety of chemical and thermal pre-treatment protocols were investigated for the as-prepared Pt/C nanostructures, as summarised in Table 1 and Table 2. A fixed amount of the Pt/C catalyst (5 mg) was used for each chemical pre-treatment.

Sodium tetrachloropalladate (Na₂PdCl₄, 98 wt% purity) and the Nafion^® 117 cationic exchange membrane were purchased from Sigma-Aldrich (Jurubatuba, Brazil). Sodium hydroxide (97 wt% purity, P.A.-ACS), sulfuric acid (98 wt% P.A.), formic acid (85 wt% purity, P.A.-ACS), glycerol (99.5 wt% purity, P.A.-ACS), and 2-propanol (99.5 wt% purity, P.A.-ACS) were acquired from Dinâmica (São Paulo, Brazil). For titration, a solution 1 mol L⁻¹ NaOH (Sigma-Aldrich, Titripur^®) and 1 mol L⁻¹ HCl (Sigma-Aldrich, Titripur^®) were used for acid and alkali quantification. Vulcan XC-72R was purchased from Cabot Corporation (Boston, Massachusetts, USA). Nafion^® (5 wt% in a mixture of aliphatic alcohols) was acquired from IonPower (New Castle, DE, USA).

TCCF samples were firstly ground with Vulcan XC72R (Cabot) conductive carbon in an agate mortar for 20 minutes. Then, the solid mixture was transferred to a conical flask, 5 wt% polyvinilidene fluoride (PVDF, Alfa Aesar) solution in N-methylpyrrolidone (Sigma-Aldrich) was added dropwise and the received suspension was stirred on a magnetic stirrer for the next 4 hours. So prepared slurry was then cast onto a copper foil by a doctor blade technique, preliminarily dried at 55 °C in air, and vacuum dried at 120 °C overnight. Round, 9 mm in diameter, electrodes where then cut, pressed on the hydraulic press at 6 t for 1 minute, weighted, dried under vacuum at 120 °C overnight and transferred to argon filled glove-box (MBraun) for the cell assembly. The obtained electrode composition was 8 : 1 : 1 (wt.) TCCF : Vulcan : PVDF.

Anodes were fabricated by preparing inks containing 80 wt% active material, 10 wt% carbon black (Vulcan XC-72R, Cabot) as the conducting agent, and 10 wt% binder, made by dispersing polyvinylidene fluoride (PVDF, Kynar blend) in N-methylpyrrolidone (NMP, Acros, 99.5% Extra Dry). The inks were homogenized through repeated and successive sonication and stirring, coated onto a copper foil (Alfa Aesar, 99.999%), dried at 100 °C under vacuum for 12 h, then pressed at 1500 lbs for 5 min. For all electrodes fabricated in this study, the active loading was 0.2–0.8 mg active material/cm². Coin cells were assembled to test the electrochemical properties of anodes in a half-cell configuration. Coin cells (2 cm in diameter, Hohsen Corp.) were assembled in an argon-filled glovebox (Labconco) with the anodes as the working electrode, lithium metal (Alfa Aesar, 99.9%) as both the counter and reference electrode, Celgard 2320 tri-layer PP/PE/PP as the separator, and a mixture of 1 M lithium hexafluorophosphate (LiPF₆, Acros 98%) in (1:1:1 vol) ethylene carbonate (EC, Acros 99+%):dimethyl carbonate (DMC, Acros 98+%):diethyl carbonate (DEC, Acros 99%) as the electrolyte.