Density Functional Theory Study of ATA, BTAH, and BTAOH as Copper Corrosion Inhibitors: Adsorption onto Cu(111) from Gas Phase

A low-coverage gas-phase adsorption of three corrosion inhibitors-3-ammo-1,2,4-triazole (ATA), benzotriazole (BTAH), and 1-hydroxybenzotriazole (BTAOH)-on perfect Cu(111) surface has been studied and characterized using density functional theory calculations We Find that the molecules in neutral form chemisorb weakly to the perfect surface in an upright geometry The strength of the chemisorption increases in the order BTAH < BTAOH < ATA with adsorption energies of -0 40, -0 53, and -0 60 eV, respectively The molecules bond to the surface with triazole nitrogen atoms and also through X-H center dot center dot center dot Metal hydrogen bonds (X = N or O) In addition to chemisorption, BTAH and BTAOH can also physisorb with the molecular plane being nearly parallel to the surface and the energies of the physisorption are 0 72 and 0 97 eV, respectively, hence being more exothermic than the corresponding chemisorption energies On the other hand, the molecules in dehydrogenated form chemisorb strongly to the surface and the strength of the chemisorption increases in the order BTAO center dot < ATA center dot < BTA center dot with the adsorption energies of -1 65. -2.22, and -2.78 eV, respectively This order is compatible with the trend of experimentally observed corrosion inhibition effectiveness on copper in near-neutral chloride solutions Although the calculations ale performed at the metal/vacuum interface, they provide enough insight to rationalize why in some experiments the BTAH was observed to be adsorbed with an upright geometry and in the others with parallel geometry