Improving the HCHO Sensing Selectivity on Ag-Doped Graphene by Oxygen Functionalization: A First-Principles Study

Graphene-based sensors typically fail in the selectivity of target gas detection when exposed to complex and multicompound atmospheres. We have thoroughly compared the adsorptions of various interfering gases (CO, NH₃, CH₄, C₂H₂, C₂H₄, CH₃OH, and CH₃Cl) with target HCHO on AgG and AgOG by first-principles simulations. The results demonstrate that AgG shows a poor selectivity for HCHO detection and an oxygen functionalized one can improve the selectivity by enhancing the adsorption strength of HCHO and weakening those of other gas molecules. Moreover, the sensing properties of the AgOG sensors are evaluated by the NEGF method, and the predicted HCHO sensing responses are 76 and 32% along the armchair and zigzag directions, respectively. The present work helps shed some light on designing graphene-based sensing materials with high selectivity.