Exploiting plasmonic effects of metal nanostructures on single graphene sheets for the study of chemical functionalization and sensing
Physical Chemistry of Solids and Surfaces, Material Characterisation
Final Report Abstract
In this project, we have developed analytical methods based on surface plasmon resonance (SPR) spectroscopy, which combine a single graphene sheet with a plasmonic gold nanostructure. On the one hand, we have optimized the preparation methodology to realize reusable SPR sensors, where the biorecognition occurs at the graphene-liquid-interface. On the other hand, we have used graphene as an electrode to study the kinetics of electrochemical processes at the graphene-electrolyte-interface in real time using the SPR sensor response. In the first part, we have developed a methodology for realizing graphene-based SPR sensors that can withstand treatment at high temperatures. A high temperature annealing step is often crucial for obtaining a clean graphene surface. Specifically, the method involves multi-step tempering coupled with chromium etching to obtain a stable gold layer on a glass chip. A graphene sheet is then transferred on to such a chip. The resulting SPR-graphene chip can be annealed up to 500°C, without any deterioration of SPR spectral quality. Hence, the same chip with near-identical sensor response can be reused multiple times by a simple annealing procedure. In the second part, we have devised a novel strategy utilizing plasmon waveguide resonance (PWR) to track the kinetics of electrochemical processes on graphene in situ. Towards this goal, we designed a polymeric waveguide layer, which is sandwiched between a graphene sheet and the gold film. The polymeric layer ensures a good electronic decoupling between the gold film and the graphene sheet. Subsequently we realized an electrochemical cell and integrated it in a microfluidic flow channel together with the ability to perform simultaneous angular reflectance measurements. The decoupled graphene sheet serves as the working electrode. Thus, we obtained the capability to perform SPR or PWR measurements with a very good control of the electrochemical potential and thereby follow the kinetics of electrochemical modification on bare graphene. Specifically, we could follow the growth of metal nanoparticles on graphene in real time and decipher the outcome of the modification from the kinetic PWR response. Moreover, redox processes occurring at the nanoparticles could also be monitored using our detection technique. In summary, we have developed a SPR detection platform exploiting single graphene sheets that can not only be used for biosensing but is also promising for studying the kinetics of electrochemical processes in situ.
Publications
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Graphene-on-gold surface plasmon resonance sensors resilient to high-temperature annealing. Analytical and Bioanalytical Chemistry, 415(3), 371-377.
Jungnickel, Robert; Mirabella, Francesca; Stockmann, Jörg Manfred; Radnik, Jörg & Balasubramanian, Kannan
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Electrochemical Surface Plasmon Resonance Sensing using a van der Waals Heterostructure. Advanced Sensor Research, 3(9).
Jungnickel, Robert & Balasubramanian, Kannan
