Influence of CeO$_2$MnO$_x$ heterostructure on Hydrogen Peroxide Electrogeneration on Carbon-Based Catalysts
The sustainable electrogeneration of hydrogen peroxide (H2O2) via the two-electron oxygen reduction reaction (2e$^-$ ORR) represents a promising alternative to conventional production methods. In this study, CeO2 and CeO2MnOx nanoparticles were synthesized and supported on Vulcan XC-72 carbon at varying loadings (1, 3, and 5%), aiming to assess the lowest metal loading and high H2O2 electrosynthesis. Physicochemical characterizations confirmed the successful formation of CeO2 nanowires and the effectiveness of the MnOx surface modification. XRD, TEM, XPS, EPR, and contact angle analyses revealed that CeO2 loading increased surface hydrophilicity through the presence of oxygenated functional groups, thereby favoring electrochemical activity. On the other hand, all CeO2MnOx loadings were statistically equivalent to Vulcan XC-72 in terms of contact angle. Electrochemical evaluations using a rotating ring-disk electrode (RRDE) demonstrated enhanced ORR activity and high H2O2 selectivity for the 1% CeO2MnOx/C and 3% CeO2/C catalysts, achieving up to 90% selectivity and elevated ring currents. The results suggest that low metal loading and surface modification via MnOx improve the balance between active site exposure, oxygen adsorption, and intermediate stabilization, thus favoring the selective 2e$^-$ pathway. These findings support the development of cost-effective, non-noble-metal catalysts for green H2O2 production via electrosynthesis.