Self-assembled SnO2/COF catalysts for improved electro-synthesis of hydrogen peroxide†

Abstract

The electrochemical oxygen reduction reaction (ORR) via a two-electron pathway offers a sustainable route for on-site hydrogen peroxide (H₂O₂) production. However, achieving stable H₂O₂ production at industrial-scale current densities continues to pose significant challenges. In this study, 10% SnO₂/COF catalysts synthesized via the self-assembly approach exhibited both high performance and robust stability. In a neutral solution, a yield of 11 873 mg L⁻¹ h⁻¹ could be achieved at a high current density of 125 mA cm⁻², with a Faraday efficiency exceeding 80% maintained throughout a 60 hour stability test. Through a series of experiments and in situ tests, it was concluded that the hierarchical porous structure of a COF enhances the mass transfer of oxygen, while the strong interaction between SnO₂ nanoparticles and the COF promotes the 2-electron (2e⁻) reaction pathway. This interaction also accelerates the desorption of hydrogen peroxide and enhances its accumulation rate. This research provides a method to design efficient catalysts for production of H₂O₂via the electrochemical 2e⁻ ORR.