Nanoparticle synthesis via femtosecond laser reduction in liquid

Uncapped “naked” Au, Ag, and Pd nanoparticles were synthesized using femtosecond laser-induced reduction of salt precursors in aqueous solution. Focusing femtosecond laser pulses into water induces optical breakdown of the medium, producing a dense plasma containing reactive electrons and radicals that can reduce metal ions to neutral metal atoms, which coalesce into nanoparticles. Manipulating the plasma composition by changing the solution pH and adding radical scavengers was found to enable improved control over the nanoparticle size distributions. The synthesized Au and Pd nanoparticles are catalytically active towards the hydrogenation of 4-nitrophenol to 4-aminophenol and could potentially be used in further catalysis applications.