The Preparation And Applications Of Nanoporous Gold Electrodes

Porous gold electrodes have been attracting increasing interest for their broad range of applications. The popular methods for fabricating porous gold electrodes are dealloying and templating, but they get involved with two or more components and/or steps. In this paper, a novel one-step method with no templates or alloys has been developed for the fabrication of a three-dimensional nanoporous gold film electrode, and the whole process has only cost less than one minute. Furthermore, the porous electrodes have been used for electrochemical catalysis and Raman spectroscopy with optimistic results. The main contents are summarized as follows:1. A three dimensional nanoporous gold film has been prepared quickly on a smooth gold substrate by applying a potential step just into the initial transition region of gold in an HC1 medium. The pore formation and structural evolution have been revealed by electrochemistry and scanning electron microscope, and the processes involved electrooxidation, dissolution, disproportion and deposition of gold. In addition, the influences of preparation conditions such as HC1 concentration, step potential and step time have also been investigated.2. The applications of nanoporous gold electrodes in electrochemical catalysis have been studied. The nanoporous electrode exhibited high catalytic activity in the electrooxidation of glucose in neutral medium. And it also showed excellent performance toward the oxidation of formic acid after being decorated with a tiny amount of platinum. Moreover, the porous electrodes with different amount of platinum have reverse effect on the electrooxidation of formic acid and methanol, and detailed illustrations are put forward to elucidate the oppositions. In the oxidation of formic acid, the exceptional catalysis of the porous electrode with a tiny amount of platinum is attributed to the high dispersal of platinum atom; while the oxidation of methanol on platinum presents remarkable "ensemble effect", so the catalysis is enhanced by the increase of platinum.3. The surface enhanced Raman scattering (SERS) of nanoporous gold electrodes, the loss and comeback of SERS activity have been explored. The as-prepared nanoporous electrode possesses fine SERS activity, and the causation of SERS is proposed preliminarily. Meanwhile, a quick (electrochemical or chemical) oxidation - (HC1) dissolution method has been brought forward to recover the SERS activity of gold substrate immediately after its loss. Moreover, we have developed a deep (electrochemical) oxidation - (glucose) reduction process to construct the SERS substrate with high activity on a smooth gold electrode.