Utilizing in-situ polymerization of pyrrole to fabricate composited hollow nanospindles for boosting oxygen evolution reaction

Abstract The fabrication of electrocatalysts with excellent activity for oxygen evolution reaction is still a challenge, due to the high energy barriers of OER which is a four-electron-transfer process. Here we designed a novel inorganic/polymer composited hollow nanospindles consist of polypyrrole (PPy) and Fe-Ni (oxy)hydroxides (FeNi-PPy HNSs) by in-situ polymerization on MIL-88(FeNi) because of the strong oxidation of Fe3+. FeNi-PPy HNSs could be used as electrocatalyst for OER directly, and high temperature sintering is not necessary. To achieve 10 and 100 mA·cm−2, the FeNi-PPy HNSs only need low overpotential of 227 and 273 mV, respectively. As shown in results of DFT, profiting from the in-situ polymerization, the metal-N coordinate bonds could enhance the performance for OER by reducing the dissociation energy of OH- and promoting the adsorption of OH- in (oxy)hydroxide. This in-situ polymerization method on MOFs to fabricate hollow nanostructures would be a potential pathway to construct highly efficient electrocatalysts.