Sodium niobate microcubes decorated with ceria nanorods for hydrogen peroxide electrogeneration: An experimental and theoretical study

Abstract

The present work investigates the catalytic activity of NaNbO3 microcubes decorated with CeO2 nanorods on carbon (1 %, 3 %, 5 %, and 10 % w/w) for H2O2 electrogeneration. The crystalline phases and the morphology of the materials were identified with scanning electron microscopy, transmission electron microscopy, X‐ray diffraction and X-ray Photoelectronic spectroscopy. Contact angle measurements were performed to characterize the hydrophilicity of each material. The H2O2 electrogeneration was assessed by oxygen reduction reaction using the rotating ring-disk electrode technique. Electrochemical characterization results shown an enhancement on the H2O2 electrogeneration by NaNbO3 @CeO2/C-based materials compared to what was obtained with pure Vulcan XC72. The 1 % NaNbO3 @CeO2/C electrocatalyst presented the lower starting potential for the ORR and a 2.3 electron transfer, favoring the 2-electron mechanism and providing a higher H2O2 electrogeneration rate. Also, the enhancement of oxygen-containing functional groups showed the potential to comprehensively tune properties and optimize active sites and, consequently, increases the H2O2 electrogeneration. Density functional theory calculations indicated that NaNbO3 and CeO2 surfaces have a similar low theoretical overpotential for this reaction and that CeO2 improves the catalyst facilitating the electron transfer. These results indicate that NaNbO3 @CeO2/C-based electrocatalysts are promising materials for in situ H2O2 electrogeneration.