Adsorption of triazole, benzotriazole, and naphthotriazole on copper

摘要

Some azole molecules have the ability to significantly slow down the corrosion of metals. Because molecular adsorption represents an important step in achieving the inhibitory effect, we performed a systematic density functional theory (DFT) study with the aim to ascertain how the adsorption characteristics of triazoles evolve as a function of molecular size [1]. Triazole, benzotriazole, naphthotriazole and copper surfaces were chosen as a model system. Atomistic computer simulations were carried out within the generalized-gradient-approximation of DFT using the Quantum-ESPRESSO package [2]. According to calculations the molecule-surface bond strength increases with increasing molecular size (see picture).This trend is explained in terms of molecular electronegativity and chemical hardness, which decrease monotonously as the molecular size increases. While the electronegativity of triazole is almost degenerate with the work function of copper surface, the electronegativity of larger acenotriazoles is smaller. The difference in electronegativity between the copper surface and acenotriazoles thus increases with increasing the molecular size, which, together with decreasing the molecular hardness, results in larger molecule-to-metal electron charge transfer and stronger molecule-surface bonds.