Influence of CeO2MnOx 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 due to oxygenated functional groups, thereby favoring electrochemical activity. On the other hand, all CeO2MnOx loadings were statistically equal 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 the electrosynthesis of green H2O2.通过二电子氧还原反应（2e⁻ ORR）可持续电合成过氧化氢（H₂O₂），是替代传统生产工艺的极具前景的方案。本研究合成了二氧化铈（CeO₂）与铈锰复合氧化物（CeO₂MnOx）纳米颗粒，并以不同负载量（1%、3%、5%）负载于瓦尔肯XC-72炭（Vulcan XC-72 carbon）上，旨在探究最低金属负载量与高效电合成过氧化氢的最优条件。理化表征证实，二氧化铈纳米线成功合成，且MnOx表面改性效果显著。X射线衍射（XRD）、透射电子显微镜（TEM）、X射线光电子能谱（XPS）、电子顺磁共振（EPR）以及接触角分析表明，二氧化铈负载量提升会通过含氧官能团增加表面亲水性，从而有利于电化学活性提升。另一方面，所有铈锰复合氧化物负载样品的接触角与纯瓦尔肯XC-72炭无统计学差异。采用旋转环盘电极（RRDE）开展的电化学评价结果显示，1% CeO₂MnOx/C与3% CeO₂/C催化剂的氧还原反应活性与过氧化氢选择性均得到增强，选择性最高可达90%，环电流显著提升。研究结果表明，低金属负载量结合MnOx表面改性，可优化活性位点暴露、氧吸附与中间体稳定三者间的平衡，从而助力选择性二电子氧还原路径的实现。上述发现为开发低成本、非贵金属基绿色过氧化氢电合成催化剂提供了支撑。