Hydrogen emission under laser exposure of colloidal solutions of nanoparticles

Abstract

We report the generation of molecular hydrogen from water by laser irradiation, without any electrodes and photocatalysts. A near infrared pulsed nanosecond laser is used for exposure of colloidal solution of Au nanoparticles suspended in water. Laser exposure of the colloidal solution results in formation of plasma of laser breakdown of liquid and emission of H 2 . The rate of H 2 emission depends critically on the energy of laser pulses. There is a certain threshold in laser fluence in liquid (around 50 J/cm 2 ) below which plasma disappears and H 2 emission stops.H 2 emission from colloidal solution of Au nanoparticles in ethanol is higher than that from similar water colloid. It is found that formation of plasma and emission of H 2 or D 2 can be induced by laser exposure of pure liquids, either H 2 O or D 2 O, respectively. The results are interpreted as water molecules splitting by direct electron impact from breakdown plasma.

Balance of O 2 and H 2 content under laser-induced breakdown of aqueous colloidal solutions

“…One should also expect the formation of gaseous products of liquid decomposition. Indeed, as it was recently shown, laser exposure of colloidal solution of nanoparticles in water is accompanied by emission of molecular H 2 [3]. There should be other gaseous products of H 2 O molecules decomposition, for example, molecular O 2 .…”

Solvents Effect on the Morphology and Stability of Cu/CuO Nanoparticles Synthesized at High Fluence Laser Ablation

“…We have examined 173 particles out of which 17% are of hollow morphology (see Figure S1(c)). The possible reason of their appearance could be attributed to the use of ethanol as solvent in which the ablation process yields H 2 and O 2 . The presence of H in the medium leads to the formation of cavities in nanoparticles by the release of H 2 .…”

Yellowing of laser-cleaned artworks: Formation of residual hydrocarbon compounds after Nd:YAG laser cleaning of gypsum plates covered by lamp black

“…Hydrogen is provided by the laser dissociation of water molecules coming both from dehydration of the gypsum surface and from the water sprayed by the operator before the laser cleaning. Indeed, in presence of nanoparticles, water radiolysis and breakdown are caused by the secondary electrons flux generated by the visible/IR laser irradiations [32,33]. Water dissociation also provides O and OH radicals allowing for oxidation and hydroxylation of the carbon precursors.…”