Among this, two-dimensional (2D) materials have emerged as a promising platform for constructing flexible and ultrasensitive sensors. It is, therefore, not surprising that integrating functional nanomaterials with electrochemical devices enhances sensitivity and selectivity by tailoring surface functionalities for the detection of H2O2 in both in vitro and in vivo environments. Among them, graphene, often referred to as the "mother" of all 2D materials, stands out due to its biocompatibility and high electrical conductivity . Despite its relatively recent development, reduced graphene oxide (rGO)/metal oxide nanocomposites have become the preferred choice for sensor development, offering enhanced surface area, improved conductivity, and greater stability . rGO acts as an ideal support material due to its high conductivity, chemical stability, and ability to promote electron transfer. While rGO provides an excellent conductive matrix and large surface area, it lacks the catalytic activity, selectivity, and efficiency required for the sensitive detection of hydrogen peroxide. The introduction of cobalt oxide (Co₃O₄) addresses the need for catalytic activity in redox reactions , while platinum (Pt) enhances the reaction kinetics and sensitivity. Thus, we hypothesized that incorporating rGO, Co₃O₄, and Pt could significantly improve the sensitivity and selectivity of detection of H₂O₂.