Abstract

The electrochemical intercalation of oxygen into La₂CuO₄ has been carried out for the first time in anhydrous organic–inorganic media such as dimethyl sulfoxide (DMSO)/0.1 M NaClO₄ or nBu₄NBF₄. The electrochemical reaction needs the presence of an oxygen source (KO₂) even with potential oxidising supporting electrolytes (NaClO₄). The anodic polarisation is performed at room temperature, with the aim of replacing the usual efficient but sometimes aggressive alkaline media. This so-called chimie douce reaction gave rise to noteworthy materials having compositions up to La₂CuO_4.08 for which superconducting behaviour was observed below 42 K. The physical characteristics of the material (XRD, chemical composition, electronic properties) before and after controlled anodic polarisation are reported. The processes are time dependent and the oxygen stoichiometry could be controlled through reaction times.