Quantum engineering the adsorption behavior and sensitivity of GaNNs toward CO gas by hetero metal CrM-GaNNSs (M = Mn, Fe, Co, Cu and Zn) co-doping: a D-PBE/DNP approach

Quantum engineering through nanostructure co-doping has emerged as a powerful strategy for bandgap modulation and the enhancement of optical, electrical, magnetic, and photocatalytic properties. This work aims to explore how the incorporation of different transition metals affects the electronic properties and CO gas sensing capabilities of GaNNSs at Grimme's dispersion-corrected PBE/DNP level of theory. Two hetero co-doped CrM(1,3)_Ga and CrM(1,5)_Ga (M = Mn, Fe, Co, Cu and Zn) configurations were designed. The structural parameters, adsorption energies (AEs), binding energies, charge transfer values, band gap energies, recovery times for gas desorption, chemical hardness, work function, electron density properties and density of states plots were calculated. The computed AEs changed from -25.0 to -30.0 and -4.0 to -21.0 kcal/mol for Cr*M and CrM* adsorption complexes, respectively. The observed changes in magnetic properties of CrMn, CrFe and CrCo co-doped GaNNSs suggest their potential for spintronic applications. A significant decrease in the H-L energy gap was observed in all hetero co-doped GaNNSs compared to pristine GaNNS. This reveals that co-doping facilitates the formation of new electronic states, which enhances electron delocalization and their performance in applications such as sensors. Upon adsorption of CO gas, the CrCu(1,5)_Ga, CrZn(1,3)_Ga and CrZn(1,5)_Ga GaNNSs demonstrate significant modification in average band gap change by 0.27 eV, 0.22 eV and 0.33 eV, and recovery times of 19 s, 8.2 s and 3.1 s, respectively, making them promising candidates for reusable sensors for detection of CO gas at room temperature. This study is anticipated to offer valuable insights into the CO gas sensing applications of hetero co-doped GaNNSs.