Halogeno-substituted indazoles against copper corrosion in industrial pickling process: a combined electrochemical, morphological and theoretical approach.

The inhibitive properties of four indazole-based compounds (IA, 4-FIA, 4-CIA, and 4-BIA) on copper corrosion in 0.5 M H2SO4 solution were investigated using electrochemical measurements, surface characterization techniques and molecular modelling methods. Electrochemical tests indicate that the inhibition efficiencies increase with incremental concentration and all halogeno-substituted indazoles (HIAs) possess superior inhibitive ability to native IA. The specific rating of inhibition performance obeys the order: IA < 4-FIA < 4-BIA < 4-CIA. All inhibition efficiencies of HIAs obtained were over 96% in 1 mM, especially, 4-CIA reaches 99.6%. Moreover, the corresponding inhibition mechanism was elucidated via quantum chemical calculations allied to molecular dynamics simulation. In summary, the present study can help us to gain insight into the effect of halogeno-substitution on the inhibition efficiency of the IA molecule.