Experimental Sensing and Density Functional Theory Study of H2S and SOF2 Adsorption on Au-Modified Graphene

A gas sensor is used to detect SF6 decomposed gases, which are related to insulation faults, to accurately assess the insulated status of electrical equipment. Graphene films (GrF) modified with Au nanoparticles are used as an adsorbent for the detection of H2S and SOF2, which are two characteristic products of SF6 decomposed gases. Sensing experiments are conducted at room temperature. Results demonstrate that Au-modified GrF yields opposite responses to the tested gases and is thus considered a promising material for developing H2S- and SOF2-selective sensors. The first-principles approach is applied to simulate the interaction between the gases and Au-modified GrF systems and to interpret experimental data. The observed opposite resistance responses can be attributed to the charge-transfer differences related to the interfacial interaction between the gases and systems. The density of states and Mulliken population analysis results confirm the apparent charge transfer in Au-modified GrF chemisorption, whereas the van der Waals effect dominates the pristine graphene adsorption systems. Calculation results can also explicate the significant SOF2 responses on Au-modified GrF. This work is important in graphene modulation and device design for selective detection.