Tuning the structural and electronic properties of GaN nanosheets through metal (M) co-doping (M = Cr, Mn, Fe, Co, Ni, Cu and Zn) to enhance the adsorption and sensing of CO gas

The co-doping of nanostructures has emerged as a crucial strategy for modulating the band gap and enhancing their optical, electrical, magnetic, and photocatalytic properties. In this work, the effect of transition metals co-doping of GaNNSs on the adsorption and sensing of CO gas was investigated. Two types of co-doped configurations, named M(1,3)Ga and M(1,5)Ga (M = Cr, Mn, Fe, Co, Ni, Cu and Zn) with a dopant concentration of M0.125Ga0.875N 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 and density of states were calculated at Grimme's dispersion corrected PBE/DNP level of theory. Compared to pristine GaNNS, a significant decrease in the H-L energy gap was observed upon Mn co-doped GaNNSs. This reveals that co-doping facilitates the formation of new electronic states, which enhances electron delocalisation and reduces the energy barrier for electronic transitions. Based on the computed band gap energy and recovery time, it is proposed that the Co(1,3)Ga, Cu(1,3)Ga and Mn(1,5)Ga can be suitable candidates for CO sensing. From adsorption energy, both Cr co-doped GaNNSs were estimated to be appropriate adsorbing surfaces for removing CO gas.