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 degrees C for 4 h with Rh(acac)3 as a precursor, water as a solvent, EDTA<middle dot>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<middle dot>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.