Varying the morphology of Fe-N-C electrocatalysts by templating Iron Phthalocyanine precursor with different porous SiO2 to promote the Oxygen Reduction Reaction

Iron phtalocyanine (FePc) is used as iron/nitrogen/carbon source to synthesized Fe-N-C electrocatalysts for ORR by pyrolysis treatment in inert atmosphere for 2 h. Various temperatures are investigated, and the most favorable temperature, 850 °C, is selected as best temperature to carry on the pyrolysis treatment. To increase the ORR activity, the morphology of the catalysts is on purpose modified with the use of different porous silica during the synthesis (SBA15 in house prepared and commercial mesoporous SiO2) as templating agent during synthesis. The use of the templating agent allows to drastically increase the specific surface area and the microporosity the catalysts, especially with the use of the commercial mesoporous SiO2. The electrocatalytic activity towards ORR of the catalysts in acid conditions is assessed by RDE and RRDE apparatuses to quantify the hydrogen peroxide production. The Fe-N-C/850_mSiO2 catalyst exhibits higher electroactivity. Furthermore, in the GDE configuration this catalyst reached a mass activity of –1.4 mA mg–1, under IR corrected conditions. The chronoamperometry performed at 0.47 V vs RHE up to 4500 min shows relatively good stability values up to 60 hours. The catalysts are characterized by means of BET, FTIR, FESEM, EDX, and XPS analyses. The obtained catalysts present a nitrogen content varying from 0.9 to 2 at.% and an iron Fe content from 0.1 to 0.5 at.%.