Graphene oxide quantum dots as potential sensor for hazardous gases: A DFT investigation

In this study, the application of pure graphene oxide quantum dots (GOQDs) and doped GOQDs as potential sensors for hazardous gases has been examined theoretically using density functional theory (DFT) computations at the B3LYP-D3/6-311 G(d,p) level of theory. For this purpose, the C24H12 functionalized with oxygen groups -OH and -COOH at the edge (as a pure GOQD) and its B2-, N2-, P2-, BN, BP- and PN- doped GOQD forms were selected. Firstly, the influence of doping on the structural and electronic properties of GOQDs has been investigated. Structurally, the replacement of carbon atoms by heteroatoms B, N, P in doped GOQDs caused significant changes in the C-X bond lengths (where X = C, B, N or P), mainly for P-doped GOQDs. TDOS and PDOS were analyzed for all GOQDs, indicating that the increase in the contribution of orbitals from the B, N and P atoms causes a decrease in their HOMO-LUMO gap. In addition, the reactivity descriptor parameters reveal that PNGOQD is the most stable of the GOQDs studied. We have also investigated the sensing mechanism of the pure and doped GOQDs for the pollutant gases such as H2S, CO2, NH3, HCN, and SO2. From the results of electrical conductivity and recovery time, BN-GOQD and BP-GOQD were the ones that showed the best results, especially for the detection of SO2 gas.