NiFe single atom catalysts anchored on carbon for oxygen evolution reaction

Single atom catalysts (SACs) can improve the efficiency of oxygen evolution reaction (OER). However, metal SACs anchored on carbon materials are relatively uncommon for the OER. In this paper, using carbon black as carrier, NiFe SACs are fabricated by one step pyrolysis method. When the weight ratio of Ni/Fe is lower than 5:3, NiFe@C exibits highly-dispersed SACs over carbon in addition to some Ni₃Fe alloy. The prepared NiFe@C 5:3 SACs showed excellent OER performance with an overpotential of 322 mV and 438 mV for current density of 10 mA/cm² and 100 mA/cm², respectively. The Tafel slope of NiFe@C 5:3 was as small as 87.6 mV/dec, indicating fast charge transfer of NiFe@C 5:3 during OER process, which was also confirmed by electrochemical impedance spectra with R_ct = 18.07 Ωcm². Meanwhile, NiFe@C 5:3 had the highest specific capacitance of 5 mF/cm² with good stability. This work provides a reference for designing electocatalyst material for efficient, stable and economical OER process.