MOFs-Derived Integrated Hierarchical Carbon Electrode for Hydrogen Peroxide Synthesis in Acidic Media.

Current research on electrosynthesis of hydrogen peroxide mainly focuses on optimizing intrinsic active sites, while overlooking the constraints imposed by mass transport limitations and weak oxygen adsorption capacity during the reaction. Herein, we developed an integrated hierarchically porous carbon electrode composed of MOF-derived porous carbon sheets arrayed on carbon cloth and epitaxially grown carbon nanotube networks, with highly active Co-Nx sites generated in situ. During the synthesis, pure water was initially employed as the solvent to promote the ordered growth of sheet-like MOFs on the carbon cloth surface. Subsequently, a confined chemical vapor deposition strategy was utilized to achieve the epitaxial growth of carbon nanotube networks on MOF-derived carbon sheets. The hierarchical structure of the electrode promotes the diffusion of oxygen, and the abundant pores significantly enhance the adsorption of oxygen, creating an "oxygen reservoir". Combined with highly active Co-Nx sites, the optimized electrode delivers an H2O2 yield of 1037 ± 20 mmol g-1 h-1 and a Faradaic efficiency of 85.5% at a current density of 26.5 mA cm-2, while maintaining stable operation for more than 50 h. In addition, the generated hydrogen peroxide was applied to the Fenton reaction for dye degradation, achieving complete degradation.