In this reaction, carbon is oxidised because it gains oxygen. At the same time, copper oxide is reduced because oxygen is removed from it.

Meanwhile, the transition metal elements, chromium, and zirconium, that comprise these alloys in the copper melt tend to react readily with oxygen and nitrogen in the atmosphere. This is ...

Oxidation reactions occurring on a catalyst rely ... to lose surface oxygen groups and causes the exchange of copper and oxygen near the catalyst surface, thinning the active CuO layer.