Hydrogen-assisted spark generation of silver nanoparticles: The effect of hydrogen content on the signal intensity in surface-enhanced Raman spectroscopy
Attila Kohut
Abstract
We employed the so-called hydrogen-assisted spark generation method to produce silver nanoparticles by means of a repetitive spark discharge in a flowing gas atmosphere. Different compositions of H2–Ar mixtures were used as carrier gas to systematically investigate the effect of the hydrogen content on the signal enhancement obtainable with silver nanoparticles in Raman spectroscopic measurements. To this end, the particles were collected on filters and used as SERS substrates without further preparation. It was shown that a ca. 50-fold signal-increase can be achieved by adding at least 30% H2 to the Ar gas. The potential causes of the enhancement were also investigated, and they were associated partly with more pronounced aggregation on the filter and partly with the increased resilience of the silver particles against surface oxidation. The latter effect was supported by control experiments with non-oxidizable gold nanoparticles, which did not exhibit considerable enhancement-variation regardless of the hydrogen content.