Novel H2S multifunctional sensing materials: Cu or Ag-decorated (4,4)SWSiC nanotubes

Density functional theory employing Grimme's D3 method was used to study the H2S sensing ability of pristine, as well as Cu or Ag decorated, (4,4)SWSiC nanotubes (NTs). The adsorption energy, most stable geometry and electronic (spin-distinct) structures of the compounds were calculated. The results show that the H2S adsorption process is exothermic, with energies of -0.391 eV (physical), -0.965 eV (chemical) and -0.618 eV (chemical) for pristine, Cu or Ag-decorated (4,4)SWSiCNTs, respectively. The range of adsorption energies points to the possible use of Cu-decorated (4,4)SWSiCNTs as an effective thermopower-based H2S sensing material. From a study on electronic structures, moreover, it was concluded that the adsorption of H2S leads to a considerable change in the corresponding energy band gaps and the carrier effective masses. The compounds under study were then treated as suitable candidates for incorporation into resistance-based schemes. Among the three compounds, the adsorption of H2S onto a Cu-decorated (4,4)SWSiCNT showed largest change (16.09%) in the true band gap and a change of 57.49% (33.36%) in the effective spin-up (spin-down) electron mass, meaning that this compound may be used with more efficiency in such schemes. Furthermore, the spin-distinct band structures of the compounds, influenced by the presence of H2S, indicate that the decorated (in contrast to the pristine) (4,4)SWSiCNTs remain magnetically bipolar. It then naturally follows that external potentials (gate potentials), needed to generate spin-polarized current, undergo an observable change when H2S is adsorbed onto the decorated (4,4)SWSiCNTs. Therefore, the decorated (4,4)SWSiCNTs can be employed in spin-current-based sensing devices. Last but not least, a complete discussion of the magnetization and the nature of the current carriers (electrons or holes), reveals that some of the compounds under investigation can potentially be used in more advanced and accurate schemes, such as magneto-based or Seebeck-effect-based H2S detection. The recovery time for the detection of H2S by any of the three compounds and the suggestions to make it shorter are also fully discussed. For completion, the physical reasons behind the electronic behavior in the compounds are given in detail. The materials presented in this article, therefore, provide new insights into the quest for designing high-performance H2S sensing devices.

Automated summary

Density functional theory was used to investigate the H2S sensing ability of pristine and Cu or Ag decorated (4,4)SWSiC nanotubes. Results suggest that Cu-decorated nanotubes may be effective thermopower-based H2S sensing materials. Adsorption of H2S led to significant changes in energy band gaps and carrier effective masses, indicating potential for resistance-based schemes. Spin-distinct band structures influenced by H2S suggest potential use of decorated nanotubes in spin-current-based sensing devices. Overall, the study provides insights for designing high-performance H2S sensing devices.