The article discusses the significance of metal-free carbon-based catalysts in the production of hydrogen peroxide (H2O2) through photocatalysis. Various carbon-based materials, including covalent organic frameworks, graphitic carbon nitride, polymer resins, carbon dots, and graphene oxide, have been investigated for their potential in H2O2 production due to their suitable energy band structure and low cost. The study reports on the synthesis of carbon-based materials from ethylenediaminetetraacetic acid (EDTA) through thermal polymerization, resulting in the formation of a conjugated carbonyl structure, N-ethyl-2-piperazinone, which exhibited highly efficient photocatalytic activity for H2O2 production. Structural analysis revealed that temperatures within the range of 260 °C to 350 °C led to the formation of active sites for H2O2 production, while temperatures outside this range showed limited catalytic activity. The research highlighted the importance of conjugated carbonyl groups as key active sites for the photocatalytic production of H2O2. Utilizing in situ characterization and density functional theory (DFT) calculations, the study confirmed the role of these groups in facilitating water oxidation and subsequent oxygen reduction reactions for H2O2 production. The findings suggest a novel approach to achieving efficient and sustainable hydrogen peroxide production through visible light-driven photocatalysis, providing valuable insights for the development of high-performance metal-free catalysts.