Reduced graphene oxide–MnO₂ nanocomposites by hydrothermal method for histamine sensor and photocatalytic activity

Herein, rGO–MnO₂ nanocomposite was synthesized via a hydrothermal method. The prepared rGO–MnO₂ powders underwent various characterizations to examine their structural, morphological, and electrical properties. XRD was used for preliminary identification of the synthesized powders, while Raman spectroscopy confirmed bond types and functional groups. UV–visible spectroscopy provided key insights into the electronic and optical properties through linear optical studies. SEM and TEM were employed to evaluate the catalyst’s morphological structure. Electrochemical sensing properties were analyzed using cyclic voltammetry, revealing that rGO–MnO₂ exhibits good sensitivity toward histamine, making it a promising candidate for real-time histamine sensing in the human body. Additionally, the rGO–MnO₂ nanocomposite demonstrated remarkable photocatalytic activity, achieving a 91.7% degradation efficiency of Eriochrome Black T, significantly higher than pure MnO₂ and rGO catalysts. This enhanced performance is primarily due to effective charge transfer from MnO₂ nanowires’ conduction band to reduced graphene oxide. Furthermore, the stability of the nanocomposite was confirmed through repeated experiments, and the key active radicals were identified using trapping experiments.