Designing sandwich-type single-layer graphene decorated by copper nanoparticles for enhanced sensing properties
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It has already been theoretically shown that sandwich-type structures prepared by stacking metal nanoparticles in two graphene layers would have exceptional optical and electrical properties for practical applications. These sandwich structures designed by band gap engineering could lead to materials capable of being developed to meet industrial demands. In order to confirm this theoretical approach, copper nanoparticle (CuNP) islands decorated in sandwich-type single-layer graphene (SLG) have been designed and used as a non-enzymatic sensor platform for the first time. Firstly, SLG has been synthesized on copper foil using a chemical vapor deposition technique and transferred onto a fluorine-doped tin oxide surface. Next, CuNPs on this SLG have been prepared using an inert-gas condensation method based on DC magnetron sputtering. A sensor platform based on the sandwich-type hetero-structure (SLG/CuNP/SLG) has been constructed by transferring another single layer of graphene onto the prepared CuNP-decorated graphene layer. In this way, a unique sandwich structure has been obtained for further applications by stacking nanoparticles with high stability, controlled size and regular particle distribution between impurity-free, large-area single layers of graphene. The sensor properties of this sandwich structure to the saccharides have been compared with those of the single-layer sensor platform (CuNP/SLG). In accordance with the theoretical studies in the literature, it has been found that the sandwich structure greatly improves sensor properties such as limit of detection, stability and response time. More importantly, it was determined that the sandwich structure acts as a shielding layer, protecting nanoparticles from electrochemical/optical and other environmental conditions.