Unprecedented Microwave‐Induced Precooled Mixed‐Acid Oxidation for Rapid and Efficient Synthesis of Graphene Oxide

ABSTRACT

In this study, we introduce the fast microwave assisted approach that integrates precooling mixture (PCM) of graphite/KMnO ₄ powder and acid (H ₂ SO ₄ /H ₃ PO ₄ ) system. This technique yields high quality graphene oxide within a minutes, having no explosive toxic gases ensuring uniform oxidation. The oxidation of graphite flakes resulted in the formation of WPGO(GO without phosphoric acid), PGO (GO with phosphoric acid, conventional), MWPGO(microwave‐assisted GO without H ₃ PO ₄ ), and MPGO(microwave‐assisted GO with H ₃ PO ₄ ), all of which were characterized through various methods, including XRD, UV–visible, FTIR, Raman spectroscopy, FESEM, TEM, SAED, EDS, XPS, and AFM. Among them, MPGO shows the best overall behavior, it has the widest interlayer spacing of 8.83 Å, a tuned oxidation level with XPS C/O = 3.15 and EDS C/O = 0.90, about 68% preserved sp ² regions, mainly single layer morphology (Γ ₂ D < 40 cm ^{− 1} ), and a moderate I_D/I_G value of 1.25. The microwave‐based paths reach 96%–97% yield in roughly 1.4 h, giving a 7.2 times faster schedule and more energy reduction, plus they remove NO _x release and keep the Mn ₂ O ₇ triggered thermal spike under control. Overall, this study offers a potentially scalable, energy saving, and inherently safer method to make structurally tuned GO, aimed for catalysis, energy storage, and functional composites.