Keywords:nanoparticles, HAXPES, electric double layer
Recently, Au nanocolloids attract many researchers due to a remarkable property. In this study, we have investigated the correlation between the particle size, the value of pH (isoelectric point) and the electric double layer at the solid-liquid interface. The Au nanocolloids were prepared using various pH electrolytes, and evaluated by the electrophoresis, UV-vis, and a hard X-ray photoelectron spectroscopy. Au nanocolloids at low pH is unstable compared with high pH, because the zeta potential is small and the particle size is increasing up. From these results of experimental and calculated of interfacial potential, pH 2.6 was observed the most unstable. In summary, we proposed that pH 2.6 is very close to the isoelectric point.