Facile synthesis of defect-rich Fe-N-C hybrid from fullerene/ferrotetraphenylporphyrin as efficient oxygen reduction electrocatalyst for Zn-air battery

Exploring remarkable oxygen reduction reaction(ORR)electrocatalysts for regenerative fuel cells and metal-air batteries is highly essential.Herein,a novel non-noble metal-based heterogeneous electrocatalyst with rich defects were successfully synthesized by liquid-liquid interfacial precipitation(LLIP)of fullerene(C_(60))and ferrotetraphenylporphyrin(FeTPP)followed by one step pyrolysis.The obtained product annealed at 700℃(C_(60)/FeTPP-700),when employed as ORR electrocatalyst,revealed a positive halfwave potential(E_(1/2))of 0.877 V vs.reversible hydrogen electrode(RHE),which was superior to that of the commercial 25%Pt/C.Delightfully,the assembled Zn-air battery(ZAB)using C_(60)/FeTPP-700 as an air-electrode catalyst exhibited a high power density of 153 m W/cm^(2),specific capacity of 668 mAh/g and long-term cycling stability for more than 250 h.Experimental results proved that the excellent electrocatalytic ORR activity of C_(60)/FeTPP-700 would attribute to the synergistic effect between FeN_xsites,Fe_(3)C/Fe nanoparticles and the structure defects.This work provides a feasible and simple method to prepare nonnoble metal-based ORR electrocatalysts for the application of energy storage and conversion.

Phase-mediated cobalt phosphide with unique core-shell architecture serving as efficient and bifunctional electrocatalyst for hydrogen evolution and oxygen reduction reaction

Hydrogen evolution reaction(HER)and oxygen reduction reaction(ORR)have been considered as two critical processes in the field of electrocatalytic water-splitting for hydrogen production and fuel cells.However,the sluggish reaction kinetics of HER and ORR required efficient electrocatalyst such as Pt to promote such process.Transition metal phosphides(TMPs)exhibit great potential to replace noble metal electrocatalysts to accelerate HER and ORR due to their high activity and easy availability.Herein,a highly-efficient bifunctional CoP electrocatalyst for HER and ORR,featuring a unique core-shell structure decorated on nitrogen-doped carbon matrix was designed and constructed via etching a cobalt-based zeolitic imidazolate framework(ZIF-67)with phytic acid(PA)followed by pyrolysis treatment(PA-ZIF-67-900).Experimental results revealed that the pure-phase single-crystalline Co P exhibited outstanding electrocatalytic performance in HER and ORR,superior to Co(PO_(3))_(2) in PA-ZIF-67-700,hybrid phase of Co(PO_(3))_(2) and CoP in PA-ZIF-67-800 and Co_(2)P-doped CoP in PA-ZIF-67-1000.To reach the current density of 10 mA/cm^(2)the as-synthesized Co P required an overpotential of 120 m V for HER in 1 mol/L KOH and half-wave potential of 0.85 V in O_(2)-saturated 0.1 mol/L KOH.This work present new clue for construction of efficient and bifunctional electrocatalyst in the field of energy conversion and storage.