Biomass-Derived Amorphous Carbon with Intrinsic Nitrogen Doping for Hydrogen Peroxide Electrosynthesis

Herein, amorphous carbon particles were synthesized from pumpkin seed biomass as a coproduct of a carbon quantum dot preparation route. The material was subsequently investigated as an electrocatalyst for the selective two-electron oxygen reduction reaction (2e^- ORR) toward hydrogen peroxide production. The results demonstrate selectivity and stability comparable to those of conventional commercial carbon, while being obtained through a simple waste-valorization strategy without additional activation or external doping steps. SEM analysis revealed fragmented particles with irregular morphology and predominantly external surface area, consistent with the low porosity quantified by N₂ adsorption (14.2 m² g^-1; pore volume 0.00597 cm³ g^-1), while XPS analyses demonstrated the presence of oxygenated surface functionalities and verified endogenous nitrogen incorporation (∼1%), indicating successful self-doping derived solely from the precursor composition. Rotating disk electrode experiments showed an onset potential of 0.738 V vs RHE, and Koutecký-Levich analyses indicated an electron transfer number close to 2, in contrast to Vulcan XC-72, which displayed mixed 2-3e^- behavior. Rotating ring-disc electrode measurements were also performed and confirmed high stability and selectivity, with an average H₂O₂ yield of ∼91.8% across 1.0-0.22 V and an average electron transfer number of 2.16. Additionally, chronoamperometry demonstrated outperforming compared to several reported carbon-based electrocatalysts. Thus, the results demonstrate that pumpkin seed-derived amorphous carbon is a sustainable and low-cost electrocatalyst with strong potential for decentralized H₂O₂ production via the 2e^- ORR pathway.