Cobalt 2 acetylacetonate

2,4-dihydroxybenzoic acid (≥99.9%), hexamethylenetetramine (≥99.9%), Pluronic P123 (≥99.0%), sodium oleate (≥99.0%), potassium sulfate (≥99.0%), sulfuric acid (95.0-98.0%), sodium perchlorate (≥99.0%), iron(III) acetylacetonate (≥99.9%), nickel(II) acetylacetonate (≥99.9%) and cobalt(II) acetylacetonate (≥99.9%) were purchased from Sigma-Aldrich. Au@SiO₂ for SHINERS experiments were purchased from XFNANO, China. Deionized water (18.2 MΩ) from an OmniaPure UltraPure Water System (Stakpure GmbH) was used for all the experiments. Carbon dioxide (99.9%), nitrogen (99.99%), argon (99.9995%) and hydrogen gas (99.9995%) were obtained from Air Liquide Singapore Pte. Ltd. Nafion 117 cation exchange membrane, and titanium screen mesh were purchased from Fuel Cell Store. The electrochemical flow cell and Ag/AgCl (3 M KCl) reference electrodes were purchased from Tianjin Aida Hengsheng Technology Development Co. The standard calibration gas mixtures for calibrating the gas chromatography system were obtained from Air Liquide Singapore Pte. Ltd. All the chemicals used in this work were of analytical grade and used without further purification.

Cyclohexanone (Grupa Azoty S.A., Puławy, Poland, ≥99.9%), cyclohexane (Grupa Azoty S.A., Puławy, Poland, ≥99,9%), cyclohexanol (Grupa Azoty S.A., Puławy, Poland, ≥99.9%), manganese(II) acetylacetonate (Sigma-Aldrich, 99%), cobalt(II) acetylacetonate (Sigma-Aldrich, 97%), sulfuric acid (Chempur, 95%), methanol (Chempur, 99.8%), acetic acid (Chempur, 99.5%), acetonitrile (Chempur, 99.5%), benzonitrile (Chempur 99.5%), N-hydroxyphthalimide (Sigma-Aldrich, 97%).

Nickel(II) acetylacetonate (Ni(acac)₂, 95%, Sigma-Aldrich), cobalt(II) acetylacetonate (Co(acac)₂, 99%, Sigma-Aldrich), iron(III) acetylacetonate (Fe(acac)₃, 97%, Sigma-Aldrich), iron(0) pentacarbonyl (Fe(CO)₅, 99.99%, Sigma-Aldrich), dicobalt octylcarbonyl (Co₂(CO)₈, >90%, Sigma-Aldrich), tri-n-octylphosphine (TOP, (P(oct)₃, 97% STREM), oleylamine (OAm, C₁₈H₃₇N, 70%, Sigma-Aldrich), octylether (C₁₆H₃₄O,
90%, TCI America), 1-octadecene (ODE, C₁₈H₃₆, 90% tech, Sigma-Aldrich), chloroform (CHCl₃, 99%, Fisher
Scientific), ethanol (C₂H₅OH, 200 proof, Decon
Laboratories), and hexane (C₆H₁₄, >98.5%,
Fisher
Scientific) were used. Fe(CO)₅, Co₂(CO)₈, TOP, and ODE were stored in a glovebox under argon. Oleylamine
was further dried over molecular sieves, while all other chemicals
were used as received.

Polyacrylonitrile (PAN) (98%, M_W = 150,000 g·mol⁻¹; BOC sciences, USA) was dissolved in N,N-dimethyl formamide (DMF) to obtain 10 wt % solutions. Cobalt(II) acetylacetonate (97%, Sigma-Aldrich, Germany) was added to the solution to obtain 1 wt % solutions considering the weight of the cobalt ions in relation to the mass of PAN. The solution was electrospun with the parameters summarised in Table 1. The acceleration voltage was set to 17 kV for cobalt-containing samples and 21 kV for the samples without cobalt additive. The samples were stabilised in air and subsequently carbonised in argon atmosphere for 3 h at temperatures between 600 and 1100 °C. Electrodes were prepared from the carbonised mats by applying a PTFE membrane by means of hot-rolling at 120 °C directly onto the mat without an additional current collector.

Iron(III) acetylacetonante (Fe(acac)₃, 99.0%), cobalt(II) acetylacetonate (Co(acac)₂, 97%), oleic acid (OA, 90%), oleylamine (OLA, 87%), benzyl ether (98%), 1,2 hexadecanediol (HDD, X%) and toluene (X%) were purchased from Sigma-Aldrich (Madrid, Spain). Ethanol was purchased from Panreac (Barcelona, Spain). All the chemicals were used as received without further purification.