Enhanced electrocatalytic activities of MoO3/rGO nanocomposites for oxygen reduction reaction

BACKGROUND The availability of highly active, low‐cost and stable oxygen reduction reaction (ORR) electrocatalysts remains a barrier to the development of energy techniques. This study presents molybdenum trioxide/reduced graphene oxide (MoO3/rGO) composite as an effective electrocatalytic material for ORR. RESULTS The nanosized MoO3 particles loaded on rGO as an efficient ORR catalyst was prepared via a two‐step method. The MoO3(0.1)/rGO nanocomposite showed the highest content of Mo6+ and rGO carbon among rGO and MoO3/rGO. The MoO3(0.1)/rGO showed the highest limiting current density of −3.04 mA cm−2 at 0.2 V versus reversible hydrogen electrode, which was comparable to the commercial 10% Pt/C in the present work. The electron transfer number of 2.74 on MoO3(0.1)/rGO indicated ORR selectivity towards the four‐electron pathway was not very high. The electrochemical active surface area of the MoO3(0.1)/rGO nanocomposite was 9.94 cm2, which was about twice the commercial 10% Pt/C. The small Tafel slope of 57.56 mV dec−1 confirms the high ORR activity of the MoO3(0.1)/rGO catalyst. The MoO3(0.1)/rGO also showed good stability under alkaline conditions and better methanol tolerance compared to the commercial 10% Pt/C. CONCLUSION The increased activity of the MoO3(0.1)/rGO composite may be attributed to the higher content of Mo6+ and rGO carbon in the catalyst. Performance of the catalysts may be further improved by optimizing the experimental conditions. The synthesized MoO3/rGO composite is a potential alternative electrocatalyst for ORR. © 2022 Society of Chemical Industry (SCI).