Enhancement of the reduction efficiency of soluble starch for platinum nanoparticles synthesis

In this work, the efficiency of soluble starch as a reducing and a stabilizing agent in the synthesis of platinum nanoparticles under acidic–alkaline treatment is systematically studied. The degraded intermediates with reducing potential (i.e., small molecules containing aldehyde and α-hydroxy ketone moieties) are concomitantly generated when the alkaline concentration is greater than 0.025 M. The in situ generated species could completely reduce platinum ions (20 mM) and sufficiently stabilize the obtained platinum nanoparticles (5 mM) of uniform particle size (2–4 nm). The reduction is efficient and rapid as a complete conversion is achieved within 5 min. In a stronger alkaline condition, the platinum nanoparticles tend to aggregate and form a bigger domain because extensive degradation generates small starch fragments with less stabilization efficiency. This observation suggests that starch is a promising green material which could be chemically treated and transformed to a powerful reducing agent and stabilizer for the synthesis of metal nanoparticles.

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► Starch degraded intermediates as reducing species in alkaline conditions.
► The platinum nanoparticles (2–4 nm) were generated by the in situ reducing species.
► Rapid reaction with 100% conversion of platinum ions into platinum nanoparticles.
► Simplified mechanism of starch degradation under alkaline conditions was proposed.