Superior suppression hydrodehalogenation performance of Pd nanoparticle decorated with metalloid-promoter GQDs for the selective hydrogenation of halonitrobenzenes

A novel Pd nanocomposites (Pd@GQDs) tightly surrounded by GQDs on the porous carbon sphere is fabricated for the application in the thermocatalytic fields. The samples were characterized by BET, UV-Vis, PL, XRD and TEM and evaluated on their catalytic selective hydrogenation performance. The results show that strong surface interaction between abundant surface groups of GQDs, especially -COO-1 group, and Pd particle induces and drives GQDs directional deposition around the Pd particle in the process of Pd@GQDs generation. In the Pd@GQDs cluster, the electron distribution of Pd particle is rearranged and Pd possesses electron-rich property. The metalloid-promoter GQDs act as an electron donor like various metal additives in multicomponent metal catalysts in the thermocatalytic fields. The Pd@GQDs generates electron-rich H other than electron-deficient H when hydrogen is adsorbed on it, which might prefer to attack nitro group in halonitrobenzene molecule, compared with C-X bond. The superior selectivity and stability for the hydrogenation of various halonitrobenzenes to corresponding haloanilines are obtained. GQDs demonstrate a great prospect of application as a nonmetallic electron promoter in thermocatalytic fields.