Specific role of chloride in anodic reactions on gold

Effects of electrolytes on the fabrication of three‐dimensional nanoporous gold films by a rapid anodic potential step method for SERS

“…(b), owing to the two properly matched competitive processes: active electrodissolution of gold facilitated by HCl and passivation of gold resulted from oxygen adsorption and phase‐oxide formation . Unlike in 2 M HCl solution, the electrodissolution of gold nanoparticles in 1 M KCl solution was slower under the chosen potential because the protective gold oxide coatings on gold nanoparticles were less soluble in neutral solution than in acidic solution . Thus, the oxide coatings of gold nanoparticles in 1 M KCl should be thicker than that in 2 M HCl, which could result in the difference in interparticle nanogaps and crevices after being dissolved.…”

“…The roughness (the solid symbols) increases with the potential step time for the two electrolytes. For the same step time, the NPGF prepared in 1 M KCl has a larger R value than that prepared in 2 M HCl, because the protective gold oxide coatings are less soluble in neutral KCl solution, preventing the formed gold nanoparticles from further amalgamation. High magnification SEM images in Fig.…”