Preparation of Palladium Catalysts Supported on Carbon Nanotubes by an Electrostatic Adsorption Method

Pd nanoparticles supported on carbon nanotubes (CNTs) with an average Pd size of around 1nm were synthesized successfully by a facile strong electrostatic adsorption (SEA) method. CNTs functionalized with various surface oxygen functional groups (SFGs) were obtained by treating the raw CNTs with concentrated HNO3 or HNO3/H2SO4. The SFGs could decrease the point of zero charge (PZC) of the CNTs and promoted the adsorption of Pd cationic complexes on the CNTs. In particular, the intrinsic and insitu formed (hydrolyzed from carboxylic anhydride groups) carboxylic acid groups of the CNTs during the adsorption process mainly influenced the adsorption of Pd cationic complexes. The SEA method was superior to the traditional incipient wetness impregnation method for the synthesis of highly dispersed Pd catalysts, which exhibited a high specific activity for the Suzuki coupling reaction.