Adsorbates on Multilayer Graphene Surface: Morphology, Distribution and Electrical Properties Here an adsorption phenomenon on the surface of multilayer graphene in air atmosphere over time was studied. We found that after 23 months, some unknown adsorbates absorbed on the surface of graphene. The adsorbate films (2nm) have no regular shape and most of them distribute on the flat graphene surface, some along the wrinkle or around a nanoparticle. The longitudinal conductivity of the multilayer graphene is substantially increased (at least 30 times) owing to the presence of the adsorbates. A reliable method to remove the adsorbates is proposed using a visible laser. This work may open up the potential application of adsorbates in graphene devices, and a new field of reliability of graphene devices.

A Langasite Crystal Microbalance Coated with Graphene OxidePlatinum Nanocomposite as a Volatile Organic Compound Sensor: Detection and Discrimination Characteristics We propose a novel langasite crystal microbalance (LCM) sensor with a graphenebased sensing medium to detect and discriminate volatile organic compounds (VOCs) at room temperature. A thin film of graphene oxide embedded with Pt nanostructures (GOPt nanocomposite) was deposited on the electrode surface of the LCM, a thicknessshear acoustic wave resonator. Ethyl acetate, acetic acid, and ethanol were chosen as typical VOCs for this study. Sensitivity and selectivity of coated LCM were investigated for different concentrations of the VOCs by analysing the resonant properties of the sensor. When exposed to VOCs, a negative shift in series resonance frequency was observed due to the mass loading of VOC molecules. Simultaneously, changes in equivalent resistance and parallel resonance frequency of the sensor were also observed due to the interaction of VOCs with charge carriers on the GOPt nanocomposite film surface. This dual measurement of both series and parallel resonance frequencies allowed for detection and discrimination of VOCs. Moreover, the high thermal stability of langasite makes the proposed sensor suitable even for harsh environmental conditions.