Metal-modified s-C3N6 as a potential superior sensing medium for effective capture of toxic waste gases CO, H2S and SO2 in the iron and steel industry based on first-principles investigations

Theoretical studies on the adsorption of toxic gases CO, H2S and SO2 on pristine and Fe, Pt, Ti-modified s-C3N6 surfaces are carried out based on first-principles investigations. Compared with pristine s-C3N6 (-0.33 eV to-0.45 eV), Fe, Pt, Ti-modified s-C3N6 structures (-1.06 eV to-2.66 eV) have larger adsorption energies for the adsorption of toxic gases CO, H2S and SO2 on their surfaces. Larger adsorption energies could lead to more CO, H2S, and SO2 molecules adsorbed on the material, thereby increasing the sensitivity. CO, H2S and SO2 molecules can reduce the band gap by 27-100% and enhance the conductivity of s-C3N6-Fe/Ti. And s-C3N6-Fe exhibits metallic properties after adsorbing CO, but it exhibits semiconducting properties after adsorbing H2S and SO2. Ab initio molecular dynamics (AIMD) calculations reveal the thermal stability of s-C3N6-Fe for the adsorption of CO and SO2. The pristine and Fe, Pt, Ti-modified s-C3N6 may be superior adsorbents as promising sensing media for the toxic gases CO, H2S and SO2.