New Study Reveals what Corroded Gold Looks Like

Naturally, gold always maintains its unique shiny metallic appearance, which has attracted human interest since ancient times and, together with its relative scarcity, has given gold its value. Gold’s resistance to corrosion also determines the majority of its applications in technology, chemistry or medicine because it remains metallic and clean even under exceptionally demanding conditions.

„On the one hand, gold corrodes only under extremely harsh conditions: it is not sufficient to immerse it in acid – you must apply an electric voltage on top of that to start so called electrooxidation,“ says Dr. Sara Barja from the University of Basque Country, the team leader of this study. „On the other hand, such harsh conditions are now being found in a range of newly developing technologies, and gold oxidation can even become desirable, for example in electrochemical reactors where renewable electricity can be used to drive chemical reactions.“

„As the corrosion begins, the gold oxide is only one atomic layer thick,“ continues Jesús Redondo from the Faculty of Mathematics and Physics, Charles University, the first author of the study. „This was the tricky part: together with my colleagues from Charles University, we had to devise a sophisticated experimental procedure in which the oxidized gold is transferred from the acid electrolyte to vacuum, where it can be characterized with the required atomic resolution.“

And what does corroded gold actually look like? Just like gold – the one atomic layer thick oxide is transparent. „Now that we understand the formation of new gold oxide phase, scientists and engineers can use this new knowledge for instance to improve the performance of electrochemical technologies,“ adds Redondo.