Seung-Hyun Hur

Direct Printing of Reduced Graphene Oxide on Planar or Highly Curved Surfaces with High Resolutions Using Electrohydrodynamics

Electrohydrodynamic inkjet printing of reduced graphene oxide (RGO) is de-monstrated to form complex geometric devices with high resolution (line width ≈ 5 mm). Both planar and highly curved surfaces (radius of curvature ≈ 60 mm) can be used as substrates. Demonstrations of counterfeit coin recognition using RGO patterns and all-printed RGO transistors suggest substantial promise for applications in security and electronics.

Multi-dimensional carbon nanofibers for supercapacitor electrodes

Four different types of porous carbon nanofibers (CNFs), plain, hollow, multi-channel (MC), and hollowed MC, were fabricated using coaxial electrospinning and thermal treatment for supercapacitor electrodes. The influence of the porosity on the specific surface area (SSA), pore volumes, and electrochemical propoerties of porous CNFs were investigated. The comparisons of their properties are a valuable work with same methods, becuase electrochemical performances are depending on the measurement conditions. Among them, the hollowed MC CNF structure was indicated the highest SSA and pore volumes. In addition, their hybrid structures with multi-walled carbon nanotubes (MWCNTs) were analyzed in therms of their porosity, SSA, and electrochemical properties for supercapacitors (specific capacitance and long-term cycling). These hybrid structures can improve overall porosity and electrochemical propoerties due to the extra mesoporous structures formed by entangling MWCNTs. In conclusion, these porous CNFs have a promising potential for various fields which need high porosity and SSA, and can be used as the platforms for catalysts, sensors, or energy devices.