Biogenically synthesized palladium nanoparticles for hydrogen evolution study: An efficient catalyst for 4-nitrophenol reduction and C-C coupling reactions

Abstract

Indian cork extract is employed for the greener production of palladium nanoparticles (Pd NPs) an effective heterogeneous catalyst with a concentration of 30.1%. Plant extract-mediated phytochemicals were found responsible for reducing Pd(II) to Pd(0) without the aid of an external reducing agent. XRD, UV–visible, and other analyses demonstrated the successful formation of Pd NPs. These NPs were evident to have better electrocatalytic activity in the hydrogen evolution reaction (HER) in an acidic medium. The Tafel slope (174 mV/dec) of the Pd NPs catalyst confirmed the Volmer-Heyrovsky mechanism for HER study and demonstrated the electrochemical desorption of hydrogen is the rate-determining step. In terms of synthetic organic chemistry perspectives, the applicability of Pd NPs has been subsequently demonstrated for the reduction of toxic 4-nitrophenol to synthetically important 4-aminophenol with a minimum catalyst loading at ambient conditions. Additionally, the outstanding catalytic activity of synthesized heterogeneous Pd NPs catalyst has been showcased for direct Heck and Hiyama cross-coupling reactions.