* Corresponding author: Fater Iorhuna  E-mail: uyerfater22@gmail.com  Tel number: +2348135789909/ +2349027089599 © 2023 by SPC (Sami Publishing Company) Progress in Chemical and Biochemical Research Journal homepage: www.pcbiochemres.com Original Research Article Comparative Study of Halogen Substituted Isocyanatophosphine as an Adsorptive Inhibitor on Al (110) Crystal Surface, using Density Functional Theory. Fater Iorhuna* a , Muhammad Abdullahi Ayuba a , Aondofa Thomas Nyijime b , Hussein Muhammadjamiu a , Mu’azu Ibrahim c a Department of Pure and Industrial Chemistry, Bayero University, Kano, Nigeria b Department of Chemistry, Joseph Saawuan Tarka University, Makurdi, Benue, Nigeria c Federal University of Technology Owerri, Imo State Nigeria A R T I C L E I N F O A B S T R A C T Article history Submitted: 2023-07-15 Revised: 2023-08-23 Accepted: 2023-09-04 Available online: 2023-09-23 Manuscript ID: PCBR-2307-1266 DOI: 10.48309/pcbr.2023.407104.1266 To shield aluminium metals from the corrosion, a theoretical investigation on the ability to resist corrosion was carried out using the local density function Becke, 3-parameter, Lee–Yang– Parr (B3LYP) under limited spin polarization DNP+ basis in aqueous solution. The aim of the research was to obtain a stable geometry of the halogen substituted Isocyanatophosphine molecule, the local reactivity, and the global reactivity of the molecules as simulated on Al (110) surface. Some of the reactivities include the (ω+) electron accepting power which is in the order of 0.614<1.404<1.739<3.165 eV with DIP having highest accepting power and (ω-) electron donating power from 4.579< 6.015<6.445<7.891 eV and DFP having the highest accepting power. The energy gap (ΔEg) was in the order of 4.243<5.142<5.993<7.361eV; hence, DIP with 4.243eV is less stable and capable of been more reactive compare to DBP, DCP, and DFP. Fraction of electron transfer (ΔN) and Back-donation energy were in good agreement with each other in the order of 0.222<0.200<0.206<0.257% having DBP as the highest efficient molecule for the inhibition. The mode of interaction between the molecules and the surface of Al (110) was therefore established to be physisorption. The Binding energy of the molecules ranges between 15.708-22.298 kJmol -1 . The Fukui function findings suggest the heteroatoms in a molecule nitrogen, oxygen, and halogen atoms been the focal point for the selectivity of electron donation and acceptance between the metal and the molecules. The molecules are tetragonal planar on the surface of the aluminium crystals. K E Y W O R D S Isocyanatophosphine Aluminium Physisorption Simulation DFT Progress in Chemical and Biochemical Research 2023, 6(3), 211-228