One-pot synthesis of Fe/Cu/N-doped carbon materials derived from shale oil for efficient oxygen reduction reaction

Abstract

In this study, the nitrogen compounds in shale oil were extracted using a metal complexation method with FeCl3·6H2O as the chelating agent. Subsequently, with complexes as raw materials, carbon materials doped with metals and nitrogen were successfully prepared using the one-pot method. The performances of the prepared Fe/Cu/N-doped carbon materials in the electrocatalytic oxygen reduction reaction (ORR) were investigated. Adding Cu to Fe@NC produced a new Fe4N species in addition to pyrrolic N-M, thereby improving the ORR performance of FeCu@NC. FeCu1.0@NC exhibited the largest content of pyrrolic-N and the highest ORR activity (initial potential = 0.8883 V, limiting current density = 6.59 mA cm−2). Its stability and methanol poisoning resistance were superior to those of commercial Pt/C electrodes. Fumed silica was used as a hard template to introduce mesopores and macropores into FeCu1.0@NC (FeCu1.0@NC-SK) and further improve its ORR activity (initial potential = 0.8973 V, limiting current density = 8.0 mA cm−2). The half-wave potential of FeCu1.0@NC-SK was 0.79 V and the electron transfer number was ∼3.99, which is close to that of commercial Pt/C catalysts. This method therefore solves the issues related to treating the complexing denitrogenation residues of shale oil, while also producing Fe/Cu/N-doped carbon materials exhibiting good ORR performances.