Fabrication of Uniformly Sized Gold Nanoparticles on Glassy Carbon by Simple Electrochemical Method

Abstract

Gold nanoparticles (AuNPs) can be fabricated on glassy carbon (GC) cathode by a galvanostatic electrolysis that employs an Au wire as anode. This electrolysis is essentially similar to a simple method that has been used to prepare platinum nanoparticles (Electrochim. Acta, 129, 152 (2014)): it is performed under the conditions that the electrolysis of water occurs in strong acid solutions such as H2SO4 and HNO3. The Au anode, where oxygen evolution occurs, dissolves to form Au ions and the GC cathode, where hydrogen evolution occurs, reduces them. Although the method is simple in principle, the prepared AuNPs are uniform in size and well dispersed on the GC surface. The size and number density of AuNPs depend on the electrolysis conditions such as the applied current and electrolysis time. The characteristics also depend on the kind of electrolyte solution: the size and density are larger when the solution is 0.5 M H2SO4 than when it is 0.5 M HNO3. This is because the dissolution rate of Au anode (i.e., the formation rate of Au ions) in H2SO4 solution is faster than that in HNO3 solution, which has been confirmed by quartz crystal microbalance.