A Corrosion Inhibitor on Metal Surfaces

Benzotriazole (BTAH) has been used as a corrosion inhibitor for copper since the 1950s. Several adsorption models have been proposed [1], however the details of how adsorption and surface passivation occur remain a matter of debate. The passivating film is thought to comprise a hydrogen bonded network embedded with some CuxBTAy polymeric sections [2].
In this contribution, various aspects of BTAH adsorption on single crystal metallic substrates, under ultra-high vacuum conditions, are presented, with the aim of characterizing such a passivating layer. Investigations on Cu(111) show that BTAH adsorbs as Cu(BTA)2 and CuBTA species, figure 1a, while the copper surface forms a (2×1) reconstruction [3, 4]. Hydrogen bonded chains are seen to form on the Au(111) surface [5], figure 1b. On Cu-doped Au(111) substrates [6, 7], BTAH selectively adsorbs on copper-rich areas forming Cux(BTA)y organometallic compounds further coordinated to the Au(111) surface through copper atoms [8], figure 1c.