Tailoring carbon-based catalysts for 2e^- oxygen reduction to hydrogen peroxide production: Mechanisms, reactor...

Hydrogen peroxide (H₂O₂) electrosynthesis through two-electron oxygen reduction reaction (2e^- ORR) has emerged as a green substitute for the traditional anthraquinone approach, owing to its mild reaction condition, low carbon emission intensity, and flexible feedstock supply. However, the 2e^- ORR activity is limited. Developing catalysts with high 2e^- ORR activity and selectivity is crucial for the effective generation of H₂O₂. Carbon-based materials have attracted great attention due to their advantage of low cost and high tunability. This review systematically summarizes the latest developments in tailoring carbon-based catalysts for efficient H₂O₂ electrosynthesis, focusing on the integrated technical chain encompassing mechanism understanding, catalyst design optimization, reactor engineering, and application expansion. The 2e^- ORR mechanism is elaborated, with emphasis on the modulation of intermediate adsorption energy by catalyst structure and the effect of electrolyte pH on reaction pathways. Subsequently, reactor engineering progress is illustrated to connect catalyst intrinsic performance with practical application, covering gas diffusion electrode design and mass transfer enhancement. Furthermore, the design strategies for tuning the geometric and electronic structures of carbon-based electrocatalysts are highlighted, along with the synthetic methods used to implement the construction strategy of carbon-based catalysts. Finally, typical application scenarios of electrogenerated H₂O₂ are introduced, including wastewater treatment, chemical upgrading, biological disinfection, and pulp bleaching. This review concludes with a discussion on current challenges and future development directions, aiming to provide comprehensive guidance for the rational design of carbon-based catalysts and the industrialization of 2e^- ORR-driven H₂O₂ production technology.