The preparation of Pt nanoparticles by methanol and citrate

Platinum nanoparticles of 2–3 nm average size and ca. ±2 nm distribution can be successfully prepared by methanol reduction while using sodium citrate as the stabilizer. Sol formation was investigated by UV–visible spectroscopy and EXAFS (extended X-ray absorption fine structure spectroscopy). The formation of Pt nanoparticles was confirmed by the presence of Pt–Pt bonding in the solution after a certain induction period in methanol-reduced sol with or without citrate. The possible two-step reduction of Pt(IV) was revealed by correlating EXAFS, UV–visible spectra and pH data. The presence of citrate resulted in a smaller Pt–Pt coordination number and a slower sol formation process. All these results prove that citrate acted as the stabilizer in this synthesis. Pt nanoparticles of ca. 2 nm average size can be successfully prepared by methanol reduction while using sodium citrate as the stabilizer. The presence of citrate resulted in a smaller Pt–Pt coordination number and a slower sol formation process.