▎ 摘　　要

Nowadays, the development of cost-effective and high-performance electrocatalysts towards Oxygen Reduction Reaction (ORR) has attracted great and increasing interest. In spite of the fact that layered double hydroxides (LDHs) have been rarely investigated towards ORR, the considerable issues of low electronic conductivity and self-aggregation of LDHs are not well addressed, which presumably lead to remarkable restrictions on mass transfer. In the present work, nitrogen and sulfur doped reduced graphene oxide (N,S-rGO) with different concentrations are incorporated for the first time into the Cobalt-Magnesium-Nickel LDH (CoMnNi-LDH) structure to improve the ORR efficiency and electrocatalytic activity. Overall, seven electrocatalysts including Graphene Oxide (GO), N,S-rGO, CoMnNi-LDH and its combination with GO and N,S-rGO with different concentrations are fabricated in this work. For assessment of the morphology and structural properties, the synthesized catalysts were characterized by FESEM, TEM, XPS, XRD, EDX, FTIR and Raman techniques. Also, in order to assess the ORR activity and durability, the electrochemical measurements (CV, LSV and chronoamperometric) are carried out for all samples. Based on the obtained results, the best ORR activity is related to the CoMnNi-LDH/15 wt% N,S-rGO electrocatalyst. This result proves that the addition of N,S-rGO to the CoMnNi-LDH with appropriate concentrations can significantly increase the electrocatalytic activity for ORR due to the synergy and strong interaction between them. The onset potential and electron transferred number (n(M)) of this catalyst are obtained to be -0.04 V vs Ag/AgCl and 3.65, respectively, which it is close to the 4e(-) pathway for the ORR. Finally, the electrocatalytic activity of prepared electrocatalysts is compared to the commercial 20% Pt/C catalyst. The new reported approach of introducing N,S-rGO support coupled with LDH electrocatalysts provides a novel opportunity to the develop cost-effective and durable electrocatalyst for fuel cell technology. (C) 2021 Elsevier B.V. All rights reserved.