First-principle study of Cu-, Ag-, and Au-decorated Si-doped carbon quantum dots (Si@CQD) for CO2 gas sensing efficacies

Abstract

Context: Nanosensor materials for the trapping and sensing of CO2 gas in the ecosystem were investigated herein to elucidate the adsorption, sensibility, selectivity, conductivity, and reactivity of silicon-doped carbon quantum dot (Si@CQD) decorated with Ag, Au, and Cu metals. The gas was studied in two configurations on its O and C sites. When the metal-decorated Si@CQD interacted with the CO2 gas on the C adsorption site of the gas, there was a decrease in all the interactions with the lowest energy gap of 1.084 eV observed in CO2_C_Cu_Si@CQD followed by CO2_C_Au_Si@CQD which recorded a slightly higher energy gap of 1.094 eV, while CO2_C_Ag_Si@CQD had an energy gap of 2.109 eV. On the O adsorption sites, a decrease was observed in CO2_O_Au_Si@CQD which had the least energy gap of 1.140 eV, whereas there was a significant increase after adsorption in CO2_O_Ag_Si@CQD and CO2_O_Cu_Si@CQD with calculated ∆E values of 2.942 eV and 3.015 eV respectively. The adsorption energy alongside the basis set supposition error (BSSE) estimation reveals that CO2_C_Au_Si@CQD, CO2_C_Ag_Si@CQD, and CO2_C_Cu_Si@CQD were weakly adsorbed, while chemisorption was present in the CO2_O_Ag_Si@CQD, CO2_O_Cu_Si@CQD, and CO2_O_Au_Si@CQD interactions. Indeed, the adsorption of CO2 on the different metal-decorated quantum dots affects the Fermi level (Ef) and the work function (Φ) of each of the decorated carbon quantum dots owed to their low Ef values and high ∆Φ% which shows that they can be a prospective work function–based sensor material. Methods: Electronic structure theory method based on first-principle density functional theory (DFT) computation at the B3LYP-GD3(BJ)/Def2-SVP level of theory was utilized through the use of the Gaussian 16 and GaussView 6.0.16 software packages. Post-processing computational code such as multi-wavefunction was employed for result analysis and visualization.