2.1.2. Synthesis of Fe-Co/N,S-MPC Catalysts

The series of nanoparticles of iron-cobalt spinel (Fe_xCo_3−xO₄) covering a wide range of nominal compositions (x = 0.5; 1; 1.5; 2; 2.5), was prepared by applying a modified procedure described by Wu et al. [23]. The mixed spinel active phase was in situ deposited on doped mesoporous carbon support (N,S-MPC) using the microwave-assisted hydrothermal route. The corresponding transition metal precursor salts, Co(NO₃)₂·6H₂O and Fe(NO₃)₃·9H₂O, were dissolved in 3.5 cm³ distilled water in the appropriate molar ratio and stirred for 30 min. After heating the solution to 80 °C, 1.5 cm³ of 25 wt.% ammonia was added and stirred for the 30 min at this temperature. The prepared mixture was next added to a carbon suspension (0.01 g C/1 cm³ EtOH), and ultrasonicated for 15 min. The resultant mixture was then transferred to a Teflon lined microwave autoclave (Ertec/MAGNUM II, Wrocław, Poland). The reaction temperature was kept at 150 °C for 30 min. The products were centrifuged and washed several times with distilled water and ethanol, and then dried at a temperature of 80 °C overnight. The obtained final catalysts (iron-cobalt spinel deposited on the N,S-MPC support) is labeled as Fe-Co_x/N,S-MPC, where x determines the iron content in the sample, e.g., for x = 0.5 − Fe-Co_0.5/N,S-MPC. For the sake of comparison cobalt spinel (Co₃O₄) deposited on doped mesoporous carbon support was synthesized (denoted Co/N,S-MPC) according to the same procedure described elsewhere. The Co/N,S-MPC catalyst was used as reference material.