Diorganyl diselenide hybrids as effective corrosion inhibitors for carbon steel in HCl solution

Herein, we present the investigation of the potential of diorganyl diselenide bis-Schiff bases N,N'-(diselanediylbis(4,1-phenylene))bis(1-(4-fluorophenyl)methanimine) (DSBSF), N,N'-(diselanediylbis(4,1-phenylene))bis(1-(4-bromophenyl)methanimine) (DSBSBr), and N,N'-(diselanediylbis(4,1-phenylene))bis(1-(2-nitrophenyl)methanimine) (DSBSNO₂) for the corrosion inhibition of steel in HCl using potentiodynamic polarization (PDP), electrochemical impedance spectroscopy (EIS), computational density functional theory (DFT) methods, and Monte Carlo (MC) simulations. The electrochemical results showed that DSBSF, DSBSBr, and DSBSNO₂ presented supreme protection efficacies of 93.84, 96.12, and 98.21 %, respectively, at 3.2 × 10⁻⁴ M. Moreover, polarization investigations showed that the prepared diselenide-based bis-Schiff bases are mixed-type corrosion inhibitors. Scanning Electron Microscopy (SEM) and Fourier Transform Infrared Spectroscopy (FTIR) observations confirm the adsorption of inhibitor molecules onto the C-steel surface, forming a protective film that effectively minimizes corrosion. This adsorption behavior aligns with the Langmuir adsorption isotherm and incorporates chemical and physical adsorption mechanisms. Additionally, the experimental results were confirmed by DFT-based parameters and MC simulation calculations. Both the experimental findings and computational results showed strong agreement. Overall, theoretical and electrochemical studies showed that the investigated diselenide-based bis-Schiff bases act as respectable inhibitors for steel acidic corrosion—their inhibition capacity upsurges when their doses are increased.