Enhanced sensing performance of carboxymethyl cellulose sodium to hydrogen sulphide gas and methylene blue dye by constructing CuO@ZnO core/shell heterostructure: A DFT/TD-DFT study

Abstract

Anthropogenic air and water pollution are two of the world's most serious public health threats, causing around 9 million fatalities each year. Accordingly, CuO, ZnO, and CuO@ZnO core/shell structures were optimized utilizing the time-dependent density functional theory (TD-DFT) method to study the effect of CuO@ZnO core/shell on the sensitivity of carboxymethyl cellulose sodium (CMC). Absorption spectra and optical band gap (Eg) have been investigated utilizing the TD-DFT method. The calculated Eg values for CuO and ZnO equal 1.23 and 3.29 eV, respectively, which agree well with those reported in the literature. The effects of H2S gas and methylene blue dye (MB) adsorption on the electronic characteristics of dimer CMC /CuO@ZnO structures were investigated in terms of TDM, HOMO/LUMO energy, and molecular electrostatic potential (MESP). The TDM in dimer CMC/CuO@ZnO structure was increased to 72.152 and 67.606 Debye, while ΔE was reduced by 6.42% and 82.57% due to the adsorption of H2S and MB dye, respectively. This means that it has a faster response to MB than to H2S. Additionally, MESP confirms the increased reactivity of dimer CMC/CuO@ZnO due to the adsorption process. As a result, dimer CMC/CuO@ZnO structures appear to be attractive candidates for H2S and MB dye sensing applications.