In situ fabricated platinum-poly(vinyl alcohol) nanocomposite thin film: A highly reusable 'dip catalyst' for hydrogenation

Abstract

Asimple protocol for the in situ generation of platinum nanoparticles in a poly(vinyl alcohol) (PVA) thin film is developed. Chloroplatinic acid as well as potassium platinum(II) chloride are used as precursors and the film is fabricated by spin coating followed by mild thermal annealing. The chemical process occurring inside the film, wherein the polymer itself acts as the reducing agent, is explored through different spectroscopy and microscopy techniques. The Pt-PVA film, < 100 nmthick and containing.1 nmsize Pt nanoparticles, is shown to be a highly efficient catalyst for the reduction of methylene blue using sodium borohydride. The ease of retrieval and reuse of the thin film is highlighted by the term dip catalyst. The reaction yield, kinetics and rate are reproducible through several reuses of the same catalyst film. Turnover number (TON=number of mols of product/number of mols of catalyst) and turnover frequency (TOF=TON/reaction time) are significantly higher than those reported earlier for this reaction using metal nanocatalysts. Utility of Pt-PVA film as an efficient catalyst for other hydrogenation reactions is demonstrated.