Complementary effect of co-doping Mn and B in Fe–N–C single-atom catalysts on enhancing the oxygen reduction reaction performance

With more flexible active sites and tunable electronic structures, electrocatalysts constructed based on doping have emerged as a frontier in various catalytic reactions. However, the mechanisms of some co-doped catalysts for the improved performance remain unclear. Herein, we report a distinctive Fe-N-C single-atom catalyst (SAC) co-doped with Mn and B, which displayed excellent oxygen reduction reaction (ORR) performance in an alkaline electrolyte, with a higher half-wave potential of 0.85 V, a lower Tafel slope (61.79 mV dec^-1), a larger kinetic current density (3.4 mA cm^-2) and a better durability than Fe-NC and Fe-BNC catalysts. Studies on the structure-activity relationship indicated that the co-doping of Mn compensated for the structural issues such as structural distortion, lattice shrinkage, increased defects, and reduction of M-N active sites caused by B doping. It also compensated for performance defects such as slow ORR kinetics, poor electrical conductivity, low selectivity, and weak stability. Consequently, this work validates the immense potential of metal and non-metal co-doped Fe-N-C SACs as active and sustainable ORR catalysts.