The reactivity of photogenerated NO32− on polycrystalline gold electrodes with different surface structures

We considered the role of the superficial atomic structure of polycrystalline gold electrodes on the electrochemical oxidation and the reduction of NO₃^2? photogenerated by trapping of electrons emitted from the electrode. The perturbation of the superficial structure of the electrode by mechanical polishing slows down the oxidation of NO₃^2?. We observed only an activated process in this case. The superficial atomic reorganization of the surface by cyclic polarization makes this reaction faster without perturbation of the short-range diffusion process of reactive species. The production of highly dispersed surfaces (black gold) gives slightly more active electrodes than the preceding one, but influences the short-distance diffusion mode in solution. The last two electrode types exhibit barrier-less and activated processes for the charge-transfer step.