Investigating metal-inhibitor interaction with EQCM and SVET: 3-amino-1,2,4-triazole on Au, Cu and Au–Cu galvanic coupling

This study reports a multiscale electrochemical investigation of the interaction between the organic compound 3-amino-1,2,4-triazole (ATA), regarded as corrosion inhibitor, and two noble metals (Cu and Au), either separated or under galvanical coupling. Open circuit potential measurements show that Cu is not protected by the application of ATA, having its potential shifted towards more negative values, while on Au exhibits a slight inhibitive effect. The adsorption free energies were determined using the electrochemical quartz crystal microbalance (EQCM), with values that correspond to physisorption on either metal. The surface reactivity of the inhibitor-modified metals in chloride-containing aqueous solution was studied using the scanning vibrating electrode technique (SVET), showing high spontaneous activity, associated to electron transfer reactions in systems containing Cu and 3-amino-1,2,4-triazole.