Theoretical study of the interaction of harmful heroin molecule with N-doped TiO2 anatase nanoparticles

Density functional theory calculations were carried out to study the interaction of heroin molecule with pristine and N-dopedTiO2 anatase nanoparticles. The oxygen atom of heroin molecule was found to be the binding site on the heroin molecule. In contrast, the binding site of TiO2 nanoparticle was positioned over the fivefold coordinated titanium atoms. The results showed that the adsorption energies of heroin on the considered nanoparticles followed the order N-doped TiO2> pristine (undoped) TiO2. The N-doped TiO2 nanoparticle was strongly favored with high sensitivity to heroin detection. Thus, the adsorption of heroin on the N-doped nanoparticle is more favorable in energy than the adsorption on the pristine one.The charge transfers were predicted based on Mulliken population analysis. The electron transfer from heroin to the TiO2 particles was in the order N-doped TiO2> pristine (undoped) TiO2.The significant overlaps in the PDOS spectra of the oxygen atom of heroin and titanium atom of TiO2 indicate that chemical bond was formed between adsorbate and nanoparticle. After the adsorption process, the electronic density in the highest occupied molecular orbitals was strongly distributed over the adsorbed heroin molecule.These processes eventually lead to the adsorption of heroin on the TiO2 particles.