Graphene has attracted great attention due to its large specific surface area,high charge carrier mobility,and excellent electrical conductivity.However,the inherent structural integrity and zero bandgap characteristics of graphene limit its gas sensing properties.Consequently,researchers have embarked on exploring avenues such as doping graphene or leveraging graphene oxide as a gas-sensitive material to design gas sensors that respond optimally to ammonia.This study,based on first-principle density functional theory,focuses on the field of ammonia gas sensors,investigating in detail the adsorption characteristics of ammonia molecules on graphene oxide (GO) and graphene oxide doped with Ag and Cu (AgGO, CuGO).By calculating parameters encompassing charge distribution,density of states,band structures,and adsorption energies,the study delves into the influence of diverse oxygen-containing groups and metal doping on the gas sensing properties of graphene oxide.The research results demonstrate a substantial charge density overlap between the density of states of hydroxyl groups in graphene oxide and NH₃ molecules,thereby indicating a pronounced chemical adsorption propensity.Particularly noteworthy is the observation that post-NH₃ adsorption,the hydroxyl-containing graphene oxide exhibits the highest charge transfer (0.078e) and adsorption energy (0.60 eV),signifying its superior adsorption efficacy towards NH₃,followed by carboxyl groups,with epoxy groups displaying comparably weaker adsorption capabilities, wherein the latter two primarily engage in physical adsorption.Furthermore,the study delves into the impact of metal doping on graphene oxide,evidencing that the adsorption capability of doped graphene oxide hinges upon the synergistic influence of oxygen-containing groups and metal atoms,with Ag-doped graphene oxide showing a several-fold increase in adsorption energy.Through density of states analysis,it transpires that Ag atoms resonate with s,p,and d orbitals of the N atom in NH₃,proving the formation of a chemical bond between Ag atoms and N atoms. Moreover,a comparative analysis shows that Cu-doped graphene oxide (CuGO) has an increased charge transfer of about 0.020e and slightly higher adsorption energy compared to Ag-doped graphene oxide (AgGO) when adsorbing NH₃.Intriguingly, under the same doping concentration,CuGO exhibits superior adsorption performance towards NH₃. Significantly,within Graphene Oxide doped with Ag or Cu,the adsorption mechanism of carboxyl and epoxy groups transitions from physical to chemical adsorption,while the hydroxyl groups maintain consistent chemical adsorption properties pre and post-doping.This suggests that doping with Ag or Cu atoms can significantly enhance the adsorption capability of graphene oxide towards NH₃.