Accelerating the oxygen reduction reaction via a bioinspired carbon‐supported zinc electrocatalyst

Abstract

Oxygen utilization in electrochemical energy generation systems requires to overcome the slow kinetics of oxygen reduction reaction (ORR). Herein, we have outstretched an efficient strategy in order for developing a bioinspired Zn (N 4 )/sulfur/graphitic carbon composite (Zn-S-Gc) with an effective performance for the ORR at low temperature. The catalyst composite was created by attaching the Zn (N 4 ) centers in the form of zinc phthalocyanine on the sulfur-linked graphitic carbon surface. The most positive ORR onset potential of about 1.00 V versus a reversible hydrogen electrode (RHE) was obtained due to the unique structure of a new catalyst in KOH solution (pH = 13) at low temperature (T = 298 K). The catalyst was evaluated using the rotating-disk electrode method in the potential range of −0.02-1.18 V versus RHE. The number of transferred electrons as one of the most important parameters (n > 3.70) is almost constant in a wide range of low overpotentials (0.1-0.6 V), which indicates a more efficient four-electron pathway from O 2 to H 2 O on the catalyst surface. The estimated Tafel slope in an appropriate range is about ≈ −133.3 mV/dec at a low current density and E 1/2 of the electrocatalyst displays a negative shift of only 11 mV after 10,000 cycles. The mean size of the catalyst centers is on the nanoscale (<50 nm). K E Y W O R D Selectrocatalyst, fuel cell, nanomaterials, nonprecious metal catalysts, oxygen reduction reaction, zinc phthalocyanine