A first-principles study on CO and CO2 gas removal and sensing on Cu and Ni-decorated Zn12O12 surfaces

The influence of transition metal (TM = Cu and Ni) doping on the electronic, magnetic, and optical sensing characteristics of the Zn₁₂O₁₂ nano-cage for CO and CO₂ detection utilizing DFT and TD-DFT calculations has been performed. The stability and chemical reactivity of the proposed TMZn₁₂O₁₂ nano-cage have been checked. The impact of CO and CO₂ gas adsorption on the energy gap (E_g), electrical conductivity, magnetic moment, and UV–Vis spectra of the pristine and TM-doped Zn₁₂O₁₂ nano-cages has been scrutinized. NBO charge, charge density difference, quantum theory atom in a molecule, recovery time, and thermodynamic analyses have been achieved. The results show that the CO and CO₂ gases are chemically adsorbed on the pristine Zn₁₂O₁₂ and TMZn₁₂O₁₂ nano-cages. The Ni and Cu doping narrowed the E_g of the Zn₁₂O₁₂ to 1.892 and 1.639 eV, respectively. The CO and CO₂ gas adsorption narrowed the energy gap of the NiZn₁₂O₁₂ nano-cage to 32.9 % and 79.3 % of its value. The CO and CO₂ gas adsorption decreases the total magnetic moment for the TMZn₁₂O₁₂ nano-cages. The Ni and Cu doping shifts the maximum absorbance peak of the Zn₁₂O₁₂ nano-cage from 380 nm to 558 and 469 nm, respectively. Additionally, the CO adsorption causes a red shift, whereas the CO₂ adsorption causes a blue shift for the adsorption peaks of the TMZn₁₂O₁₂ nano-cages in the visible region. Thus, our results may be fruitful for designing novel electrical, magnetic, and optical gas sensors for CO and CO₂ gases based on the NiZn₁₂O₁₂ and CuZn₁₂O₁₂ nano-cages.