Nitrogen-doped hollow carbon spheres with highly graphitized mesoporous shell: Role of Fe for oxygen evolution reaction

There are many studies portraying iron (Fe) and nitrogen (N)-functionalzed carbon as an electrocatalyst along with possible elucidation of catalytically active sites. Despite continuous controversial debate on the active sites/species, the presence of N is believed to be undeniably needed for the efficient catalysis, whereas the necessity and role of Fe are still debated. To clearly understand the role of Fe in Fe and N-functionalized electrocatalyst, N-doped hollow mesoporous shell carbon (N-HMSC) is prepared as a uniform model electrocatalyst by a simple template nanocasting using Fe phthalocyanine (FePc) as a single precursor for carbon, N, and Fe. It is found that the presence of Fe in N-HMSC leads to the efficient graphitization of N-HMSC structure, which can be beneficial for electrocatalytic oxygen evolution reaction (OER). Interestingly, it is observed that Fe is a must for the preparation of high efficient catalyst, but may not be necessary for OER.