Session: Physical Chemistry Poster:

The photochemical reduction of [AuCl₄]^-ions to form Au nanoparticles (AuNPs) have widely been studied using femtosecond (fs) laser pulses. The use of nanosecond (ns) laser pulses to induce this conversion have not been previously explored. The irradiation of aqueous [AuCl₄]^-with 532 nm, 8 ns pulses at intensities well below the optical breakdown (OB) threshold of water produced near monodisperse (PDI = 0.04) 5 nm AuNPs without additional chemical reducing or capping agents. The AuNP growth kinetics is governed by a plasmon-enhanced photothermal autocatalytic mechanism. On the other hand, the irradiation of aqueous [AuCl₄]^-by 800 nm, 30 fs pulses under similar conditions resulted in 14 nm AuNPs via an autocatalytic process that involves the photolysis of water. Au-graphene oxide (Au-GO) nanocomposites were prepared by the photoreduction of [AuCl₄]^-in aqueous GO by both ns and fs laser pulses. The presence of GO significantly accelerates the [AuCl₄]^-photoreduction rate, having a stronger effect with the ns laser pulses. The Au-GO nanocomposites are used for applications such as biomedical sensing, photothermal cancer treatment, heterogenous catalysis, and optoelectronics.

Dr. Julian A Bobb

Postdoc, Virginia Commonwealth University

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