Construction of Co3O4-Ni3S4-rGO ternary hybrid as an efficient nanoelectrocatalyst for methanol and ethanol oxidation in alkaline media

Abstract

In this study, a three-component nanocatalyst consisting of cobalt oxide (Co3O4), nickel sulfide (Ni3S4), and reduced graphene oxide (rGO) is synthesized by the hydrothermal method. Physical characterization confirmed the successful synthesis of these nanocatalysts. In this study, Co3O4- Ni3S4 (CN) and Co3O4- Ni3S4 -rGO (CNR) is reported for application in alcohol fuel cells for the first time. Electrochemical investigations show that both nanocatalysts have relatively good efficiencies in the methanol and ethanol electrooxidation process. Adding rGO to the CN structure causes the nanocatalyst to gain a higher specific surface area and increase its electrical conductivity. CNR showed 96% stability in the methanol oxidation reaction (MOR) process and 94% stability in the ethanol oxidation reaction (EOR) process. The electron transfer kinetics are investigated in the MOR and EOR processes. CNR indicates the exchange current of 8.61 × 10−7 mA/cm2 in MOR and 1.87 × 10−7 mA/cm2 in EOR that is higher than the exchange current of CN, which proves a clear reason for the excellent effect of adding rGO to the nanocatalyst. In this work, the synergistic effect of Co3O4 as metal oxide and Ni3S4 as metal sulfide, and rGO as a conductive substrate is investigated. Finally, CN and CNR nanocatalysts introduce as stable and inexpensive catalysts in MOR and EOR processes for use in alcoholic fuel cells.