Microwave-Assisted Facile Hydrothermal Synthesis of Fe3O4–GO Nanocomposites for the Efficient Bifunctional Electrocatalytic Activity of OER/ORR

Abstract

A challenging task is to develop and improve the efficiency of the electrocatalysts for bifunctional oxygen reaction activities for the higher generation of current with lower overpotential. In the present work, ultrafine Fe₃O₄ nanoparticles were uniformly decorated on the layered surface of graphene oxide (GO) sheets using the microwave-assisted hydrothermal method and successfully tested for bifunctional oxygen reaction activities for the first time. This heterostructure composites were used as a promising candidate for highly efficient bifunctional material for oxygen evolution/reduction reactions (ORR/OER) in both KOH and H₂SO₄ solutions. The composite structure and morphology were characterized by scanning and high-resolution transmission electron microscopy, Raman spectroscopy, X-ray diffraction, and X-ray photoelectron spectroscopy. These heterostructure composites show a very low onset potential value for ORR (0.975 V vs RHE) and OER (1.25 V vs RHE) in the presence of KOH solution. Additionally, the composites exhibit superior performance activity for ORR (0.92 V vs RHE) and OER (1.2 V vs RHE) in sulfuric acid solution. Interestingly, the pure GO showed a better result than the previously reported work that supported the superior electrocatalytic performance of the hybrid composites. This coupling of techniques provides a higher density of Fe–C–O crystalline sites and ultrafine Fe–O particles as boosting higher charge transferability in the composites. This physicochemical behavior facilitates in breaking the functional groups on the surface and providing more active transfer sites that are influenced by microwave and hydrothermal processing. This study may provide useful insights into the Fe-enabled high bifunctional activity to guide the design of an efficient catalyst for many potential electrochemical activities.