Boat‐, Cuboid‐, and Dumbbell‐Shaped Hierarchical Morphology of Cerium (IV) Hydroxidophosphate Materials for Oxidative Coupling Reaction

Abstract A simple hydrothermal approach was used to obtain boat‐, cuboid‐, and dumbbell‐shaped hierarchical morphology of cerium (IV) hydroxidophosphate materials. The period of the reactions, pH, and types of bases play crucial roles in tuning the morphology of the material. PXRD, FE‐SEM, HR‐TEM, FT‐IR, XPS, EDX, and EPR spectroscopies were used to analyze the materials. FE‐SEM and HR‐TEM analysis show that the materials have hierarchical morphology. According to XPS and EPR analysis, the materials comprise a redox‐active Ce³⁺/Ce⁴⁺ couple. The thiol to disulfide oxidative coupling reaction is synergistically boosted by the hierarchical morphology and redox‐active Ce³⁺/Ce⁴⁺ couple. The catalyst has excellent catalytic activity both in aqueous as well as protic organic solvents. However, the catalyst exhibited no reactivity in common organic solvents such as CH₃CN, DCM, and THF. The catalytic reaction was thoroughly investigated in the presence of various solvents, catalyst amounts, oxidising agents, and substrates. In the presence of H₂O₂, the yield is 99%, whereas in the presence of air, it is 79%. We found high yields for several aromatic thiols but aliphatic thiols exhibited relatively poor yields under identical conditions.