Effect of carbon nanosheets with different graphitization degrees as a support of noble metals on selective hydrogenation of cinnamaldehyde

In this work, Pt and Pd catalysts supported on carbon nanosheets (CNS) with different graphitization degrees were prepared via a simple borohydride reduction method. The effect of graphitization degree on the catalytic activity of Pt/CNS and Pd/CNS was investigated to obtain the optimal activity. The prepared catalysts were well characterized by X-ray diffraction (XRD), Raman, transmission electron microscopy (TEM) and X-ray photoemission spectroscopy (XPS). The activity and selectivity of Pt/CNS and Pd/CNS catalysts increases with the rise of the graphitization degree of CNS. A high graphitization degree of the CNS support can enhance the transfer of electrons from the CNS support to Pt and Pd nanoparticles, leading to the increase in the surface Pt-0 and Pd-0 content. The more surface Pt-0 and Pd-0 content the catalyst has, the higher selectivity to COL and CALD it exhibits, respectively. The good graphitization degree of the CNS support is an advantage of the strong p-p interactions between CAL and the surface sp(2)-bonded of CNS support. Thus, the different catalytic activity and selectivity over the Pt/CNS and Pd/CNS catalysts are attributed to the surface Pt-0 and Pd-0 content and the adsorption capacity for CAL on the catalyst surface that are closely related to the graphitization degree of CNS.