Rubidium- and Copper-Doped CeO₂ Nanorods for the Oxidative Coupling of Anilines

The catalytic production of aromatic azo compounds by aniline’s oxidative coupling process is significant in organic synthesis. However, the catalysts used in this method generally exhibit low selectivity for the desired products and need costly preparation methods. In this study, for the first time, we proposed a species regulation strategy to synthesize the Rb-doped Cu/CeO2 nanorod catalyst, which showed high conversion (98%) and selectivity (95%) toward oxidative coupling of aniline to azoxybenzene using H2O2 as the oxidant. Aniline radical ion trapping experiments demonstrated that the oxidative coupling of aniline to azoxybenzene follows a nitrosobenzene intermediate mechanism. Characterization studies revealed that the addition of Rb not only enhances the interaction between Cu species and CeO2 but also increases oxygen vacancy content. DFT calculations indicate that the Cu–Ce and Rb–Ce interfaces are the main active sites, offering excellent catalytic performance. The reusability test for five cycles shows good stability of a Rb–Cu/CeO2 nanorod catalyst. The study provides a promising species regulation strategy for Rb-promoted nanocatalysts with ultrahigh selectivity, expanding their applicability in oxidative coupling and related reactions.