Green Synthesis of Platinum Nanoparticles by Electroreduction of a K2PtCl6 Solid-State Precursor and Its Electrocatalytic Effects on H2O2 Reduction

A new synthesis route for Pt nanoparticles by direct electrochemical reduction of a solid-state Pt ion precursor (K2PtCl6) is demonstrated. Solid K2PtCl6-supported polyethyleneimine (PEI) coatings on the surface of glassy carbon electrode were prepared by simple mixing of solid K2PtCl6 into a 1.0% PEI solution. The potential cycling or a constant potential in a PBS (pH 7.4) medium were applied to reduce the solid K2PtCl6 precursor. The reduction of Pt(IV) began at around -0.2 V and the reduction potential was ca. -0.4 V. A steady state current was achieved after 10 potential cycling scans, indicating that continuous formation of Pt nanoparticles by electrochemical reduction occurred for up to 10 cycles. After applying the reduction potential of -0.6 V for 300 s, Pt nanoparticles with diameters ranging from 0.02-0.5 mu m were observed, with an even distribution over the entire glassy carbon electrode surface. Characteristics of the Pt nanoparticles, including their performance in electrochemical reduction of H2O2 are examined. A distinct reduction peak observed at about -0.20 V was due to the electrocatalytic reduction of H2O2 by Pt nanoparticles. From the calibration plot, the linear range for H2O2 detection was 0.1-2.0 mM and the detection limit for H2O2 was found to be 0.05 mM.