Electrostatic adsorption-microwave synthesis of palladium nanoparticles on graphene for improved cross-coupling activity

Abstract

Graphene materials as catalyst supports have shown tremendous promise for improving catalytic activity. Pd nanoparticles supported by graphene defects have been shown to improve catalytic activity in Suzuki reactions, but understanding their formation and factors that affect their formation is still elusive. In order to gain a better understanding of this phenomenon, a new synthetic method was developed combining strong electrostatic adsorption method for directed ionic Pd precursor uptake with a new solventless microwave irradiation method to simultaneously form Pd nanoparticles and graphene defect sites. Catalytic activities an order of magnitude higher than commercial Pd-carbon catalysts were obtained using this new method with low microwave powers, short reaction times, under atmospheric conditions, and without the use of reducing agents or solvents. The systematic comparison of catalysts synthesized from four different graphene materials and two different Pd precursors revealed Pd-graphene defects form through three routes that are affected by the initial oxygen content of graphene support and choice of ionic Pd precursor.