Hydrogen peroxide electrosynthesis: A comparative study employing Vulcan carbon modification by different MnO2 nanostructures.

• Simple synthesis of MnO2 nanostructures by hydrothermal method • Comparative ORR study for different nanostructured-MnO2 modifying Vulcan XC-72 • Highest H2O2 electrogeneration using 1% α-MnO2/Vulcan XC-72 (402 mg L-1) The electrochemical performances of the α-MnO 2 /Vulcan XC-72 and δ-MnO 2 /Vulcan XC-72 nanostructures in hydrogen peroxide (H 2 O 2) electrosynthesis were compared herein. Both materials were synthesized by a simple hydrothermal route. Their structures and morphologies were analyzed by SEM, HRTEM, XPS, Raman Scattering and XRD, and their ORR electrochemical properties and H 2 O 2 electrosynthesis efficacies were investigated in alkaline NaOH solutions applying the rotating ring-disk electrode (RRDE) technique. Gas diffusion electrode (GDE) setups in acid media aiming at H 2 O 2 formation were also performed. The 3% δ-MnO 2 /C and 1% α-MnO 2 /C electrocatalysts were more efficient and selective than pure Vulcan XC-72 through the ORR 2-electron pathway in the RRDE essays. Concerning H 2 O 2 electrogeneration using GDE, the 1% α-MnO 2 /C electrocatalyst displayed better activity, with peroxide accumulation of 402.6 mg/L at -1.9 V (vs Ag/AgCl) after 120 min, 48 % higher than pure Vulcan XC-72 GDE. These results can be ascribed to a synergistic effect between α-MnO 2 and Vulcan XC-72, as well as oxygen functional acid species improvement, increasing electrocatalytic surface hydrophilicity and enhancing H 2 O 2 electrosynthesis. [Display omitted] [ABSTRACT FROM AUTHOR]