Adsorption performance of TM doped (TM = Fe, Ni, Cr and Zn) silicon carbide nanotubes towards formaldehyde: a DFT-M06-L study

Abstract

In this work, the adsorption of formaldehyde (H2CO) on the surface of transition metal-doped silicon carbide nanotubes (TM-SiCNTs; TM = Fe, Ni, Cr and Zn) were scrutinised by using M06-L meta-generalised gradient approximation (m-GGA) exchange–correlation functional. Two types of TMSi–SiCNTs and TMC–SiCNTs doped nanostructures were found on the potential energy surfaces. The obtained results indicate that the TMSi–SiCNTs are more stable than TMC–SiCNTs. The adsorption energies of H2CO on the TM doped SiCNTs are computed to be in the range of −0.55 to −2.52 eV. The sequence of H2CO adsorption energies on the metal-doped silicon carbide nanotubes are H2CO-CrC-SiCNT > H2CO-FeC-SiCNT > H2CO-FeSi-SiCNT > H2CO-CrSi-SiCNT > H2CO-NiC-SiCNT > H2CO-ZnC-SiCNT > H2CO-NiSi-SiCNT > H2CO-ZnSi-SiCNT. In comparison with the pure SiCNT, the HOMO–LUMO gap decreases and electrical conductance increases. The change in the HOMO–LUMO gap of NiC-SiCNT is predicted to be greater than those of others. Therefore, the NiC-SiCNT is predicted to be more sensitive than other metal-doped NTs to H2CO gas. These results give new insights into the applications of TM-SiCNTs materials in H2CO gas sensing.