The Fabrication And Analytical Application Of Electrochemical Sensors Based On Nanoporous Gold

Nanoporous gold(NPG) not only has conductivity and malleability as bulk gold, but also has some unique nature as nanomaterials, such as small size effect, surface effect, quantum size effect and quantum tunnel effect. The current methods to fabricate NPG electrodes can be categoried to dealloying method, templating method and electrochemical method.The last method is relatively simple and environmentally friendly,because it avoids the disadvantages of multi-step template treatment or multi-component alloy preparation.This paper aims to build NPG or cobalt oxides modified NPG electrode and study their catalytic performances for small molecules such as glucose and hydrazine hydrate, and explore its potential application in electroanalysis. The main contents are summarized as follows:(1) NPG has been prepared with a high specific surface area by anodic potential step method in ammonium chloride electrolyte with hydroxylamine hydrochloride as depolarizing agent. The step time and the impact of hydroxylamine hydrochloride on NPG roughness have been studied. Cyclic voltammetry(CV), chronoamperometry and Raman spectroscopy technique are applied to illustrate gold anodizing process in chloride containing electrolyte. The electrochemical behavior of glucoseon NPG electrode has been explored, and nonenzymatic detection of glucose has been conducted under neutral and alkaline conditions.(2) CoHCF was modified on NPG surface and further transformed into CoOx in an alkaline solution. The impact of electrolyte concentration and pH on the preparation of CoOx/NPG were discussed. The surface morphologies and chemical component of NPG, CoHCF/NPG and CoOx/NPG were characterized by SEM, TEM and XPS. Electrooxidation behavior of glucose in NaOH were detailed compared among NPG,CoOx/NPG and Co Ox/GC electrodes. A linear relationship was established between glucose concentration and current density by CV and chronoamperometry techniques respectively. The prepared CoOx/NPG sensor was successfully measured glucose levels in human serum.(3) NPG was fabricated to build a sensor for rapid detection of hydrazine hydrate concentration. The CVs of hydrazine hydrate on smooth gold, NPG and glassy carbon electrodes were compared. Further,the effect of scan rates and electrolyte p H on hydrazine hydrate electrooxidation on NPG has been investigated in detail. NPG electrode exhibited high sensitivity and wide detection range to hydrazine hydrate no matter in PBS electrolyte or NaOH electrolyte.