Electrodeposition of Silver Nanoparticles on Indium-Doped Tin Oxide Using Hydrogel Electrolyte for Hydrogen Peroxide Sensing

Nanoparticles are used in various fields, including fuel cells, energy conversion devices, and sensors, because of their large surface area and excellent catalytic properties. Although various methods of synthesizing nanoparticles are available, the most popular is the solution-phase reduction of metal ions. Electrodeposition is a method of reducing metal ions in solution and is widely used because of its various advantages. In this study, Ag nanoparticles with a narrow size distribution were evenly dispersed on the surface of an electrode by applying electrodeposition in an agarose hydrogel medium instead of in solution, confirming the feasibility of Ag deposition in agarose hydrogel, even at a lower reduction potential than that in solution. These results are attributed to the electrolyte effect owing to the hydrophilic backbone of the agarose hydrogel and the gel effect, which reduces unexpected convection. H2O2 was detected by using the Ag nanoparticles synthesized in agarose hydrogel, and the limit of detection for H2O2 was found to be 4.82 µM, with a dynamic range of 1–500 µM. The nanoparticle synthesis platform proposed in this study is expected to be actively used for the synthesis of other metal/nonmetal nanoparticles.