Iron 2 acetate

The synthesis of Fe-N-C was conducted according to the literature [7 (link),18 (link),33 (link),34 (link)]. For the synthesis of Fe-N-C materials, 100 mg of carbon support was impregnated with a mixture of 16.25 mg iron(II) acetate (≥99.99%) and 421 mg of cyanamide (99%), both purchased from Sigma Aldrich (Darmstadt, Germany) in ethanol (Carl Roth) and mixed in a sonication bath until complete evaporation of the solvent and dried in vacuum oven at 30 °C overnight. Pyrolysis was carried out for 1 h at 900 °C at a heating rate of 5 °C/min and 100 L/h of nitrogen flow in a ceramic tube furnace followed by acid leaching with 2 mol/L of H₂SO₄ purchased from Carl Roth for 16 h at 90 °C. After washing the catalyst powder until neutral pH and drying, a second pyrolysis step similar to the first one was performed.

Vanadium(III) chloride (VCl₃, ≥99.0%), chromium(III) chloride hexahydrate (CrCl₃·6H₂O, ≥98.0%), manganese(II) acetate tetrahydrate [(CH₃COO)₂Mn·4H₂O, ≥99.0%], iron(II) acetate [Fe(CO₂CH₃)₂, ≥99.99%], nickel(II) acetate tetrahydrate [Ni(OCOCH₃)₂·4H₂O, ≥99.0%], hexamethylenetetramine (HMT; C₆H₁₂N₄, ≥99.0%), and potassium hydroxide (KOH, 99.99%) were purchased from Sigma-Aldrich. Titanium(IV) oxide (TiO₂, ≥99.0%) was purchased from EMD Chemicals. Cobalt(II) chloride hexahydrate (CoCl₂·6H₂O, 99.9%) was purchased from Alfa Aesar. HiSPEC Platinum 20% on carbon (20 wt % Pt/C) with an average particle size of 3 nm was from Johnson Matthey Fuel Cells. High–surface area Ketjen Black carbon powder (EC-600JD) was purchased from AkzoNobel. Absolute ethanol, used during synthesis, was purchased from Fisher Scientific. High–surface area Ketjen Black EC-300J supported PtRu catalysts (PtRu/C, 60 wt %), D2021 Nafion dispersion (20 wt %), and AvCarb MGL190 carbon paper (190 μm thick) were purchased from the Fuel Cell Store. QAPPT (ion-exchange capacity = 2.50 ± 0.05 mmol/g, 25 ± 2 μm thick) membrane and ionomer binder were purchased from Eve Energy. Deionized water (18.2 megohm·cm) was obtained from a Barnstead Nanopure water purification system. All chemicals were used as received, without further purification.

The following reagents
were precursors for the modified polyol synthesis of tetrahedrite
nanoparticles and were used as received from Sigma-Aldrich Chemical
Co.: antimony(III) acetate, (Sb(C₂H₃O₂)₃, ≥99.99%), copper(II) acetate monohydrate (Cu(C₂H₃O₂)₂·H₂O, ≥98%), sulfur powder (99.98%), zinc(II) acetate (Zn(C₂H₃O₂)₂, 99.99%), iron(II)
acetate (Fe(C₂H₃O₂)₂,
95%), nickel(II) acetate tetrahydrate (Ni(C₂H₃O₂)₂·4H₂O, 98%), manganese(II)
acetate (Mn(C₂H₃O₂)₂,
98%), and cobalt(II) acetate (Co(C₂H₃O₂)₂, 99.99%). Tetraethylene glycol (99%) from Alfa Aesar
and ThermoScientific was the solvent, while sodium borohydride powder
(NaBH₄, ≥98.0%) from Sigma-Aldrich was used as the
reducing agent. Anhydrous ethanol (200 proof, USP grade) from Pharmco-Aaper
was utilized to isolate the product.

l-Lactide and 4-N,N-dimethylaminoacetophenon (TCI, Eschborn, Germany), 1,8-octanediol (Sigma-Aldrich, Munich, Germany), N-tert-butylacetamide (Fluorochem, Hadfield, UK), and acetanilide (Merck, Darmstadt, Germany) were purified by recrystallisation (twice) from THF. 2-Chloro-N,N-diethylacetamide (Sigma-Aldrich, Munich, Germany), and 1,3-dimethyl-2-imidazolidone (ABCR, Karlsruhe, Germany) were dried over CaH₂ at room temperature under stirring for 24 h, and after separation from the hydride degassed with nitrogen. N-Ethylacetamide, N,N-diethylacetamide, N,N-dimethylacetamide and tetramethylUrea (Merck, Darmstadt, Germany) were dried over CaH₂ at room temperature for 16 h, followed by distillation and storage under N₂. Urea (Merck, Darmstadt, Germany or BASF, Ludwigshafen, Germany), was used as received or recrystallised from dry ethanol and stored under N₂ until use. ε-Caprolactone (99%, Sigma-Aldrich, Munich, Germany) was distilled under vacuum and stored under N₂ over molecular sieves. 1-Hexanol (Acros Organics, Nidderau, Germany; 99%, extra dry) was used as received. Iron(ii) acetate (99.995%, Sigma-Aldrich, Munich, Germany) was stored under N₂ atmosphere.

The sugarcane bagasse used was obtained from a commercial producer of sugarcane juice, located in the city of Salvador, BA, and the sugarcane was cultivated in the municipality of São Felipe, BA. Iron(II) acetate (Sigma-Aldrich) and commercial iron(III) nitrate nonahydrate (Vetec) were used as precursor salts to obtain iron oxides and were used directly without treatment. The methylene blue (MB) (Synth) solutions in the desired concentration range were made using ultrapure water (electric conductivity 0.05 μS/cm).