Modulating Cu valence state in Cu and graphene oxide composites for electrocatalytic tetracycline hydrochloride degradation.

Cu and graphene oxide composites (Cu-GO) were designed by anchoring Cu via oxygen groups in GO based on the heavy co-relationships of copper (Cu) anode electrocatalytic activity with Cu valence state. With the consumption of oxygen groups under various pyrolysis temperatures, the Cu valence state changed from Cu ions (as CuCl and CuCl) to Cu oxide (CuO and CuO) and the final metallic Cu. In which the Cu in CuCl was more favorable for electrocatalytic oxidation than other Cu valence states. Due to the dramatic contribution of O and active chlorine, 100% degradation efficiency was achieved using tetracycline hydrochloride (TCH) as the target pollutant. Cu showed a selective preference for O and active chlorine triggering, rather than metallic Cu. Under the attack of O and active chlorine, the degradation intermediates of TCH were then provided by LC-MS results. The final results not only prove the feasibility of the Cu-GO/electrocatalysis system for pollution control but also shed light on the anode design via Cu valence state modulation.