Abstract
Prolonged cathodic polarisation of gold and gold alloy electrodes in the hydrogen evolution potential range is a typical operating condition in electroplating applications. Electrodic hydrogen evolution gives rise to superficial failures such as blistering and cracking. These types of damage can eventually cause electroformed objects to fail by macroscopic cracking. The development of these defects is connected with the evolution of the morphology and of the crystallographic and electronic properties of the electrode. In particular, progressive roughening can be detected, giving rise to unexpected and irreproducible behaviour of cathodic systems based on gold and its alloys. In this paper the time dependent behaviour of cathode modification brought about by hydrogen evolution, giving rise to morphological and related electrocatalytic effects, is investigated. The study is based on in situ and ex situ optical microscopy and electrochemical measurements (cyclic voltammetry and impedance spectroscopy) carried out in neutral aqueous solutions containing chloride.
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