Ultrathin Rh Nanosheets as a Catalyst for the Selective Hydrogenation of Phenol to Cyclohexanone

The syntheses and catalytic application of two-dimensional (2D) metallic nanomaterials have attracted much attention due to their extraordinary physical, electronic, chemical, and optical properties. Herein, well-defined large-size ultrathin Rh nanosheets with a thickness of approximately 0.72 nm were successfully prepared by using one step solvothermal method at 180 °C for 4 h with Rh(acac)₃ as a precursor, water as a solvent, EDTA·2Na as a stabilizer, and HCHO as both a reducing agent and a shape-controlling agent. The formation of the large-size ultrathin Rh nanosheets was dependent upon EDTA·2Na as well as the selective adsorption of CO, which was originated from HCHO decomposition during the reaction process, on (111) facets of Rh nucleus. The as-synthesized ultrathin Rh nanosheets exhibited excellent catalytic activity and high selectivity of cyclohexanone in hydrogenation of phenol. 100% conversion of phenol as well as 79.74% selectivity of cyclohexanone was achieved over the ultrathin Rh nanosheets with 0.5 MPa H₂ pressure at room temperature within 1.5 h. These results provide a synthesis strategy for ultrathin precious metal nanosheets with catalytic applications.