Rajib Paul
Case Western Reserve University, USA
Title: Hierarchical 3D materials with vertically aligned carbon nano-structures for efficient energy applications
Biography
Biography: Rajib Paul
Abstract
Carbon based structural materials are attractive for energy application owing to their fascinating thermal and electrical conductivities, excellent mechanical properties and efficient catalytic activities. The sp2 hybridization in graphitic carbon lattice is responsible for such properties. The defect-free graphitic carbon structure is crucial for superior transport and mechanical properties whereas the structural or heteroatom induced defective states are desirable for efficient catalytic activities. However, the catalytic activities in defect-rich carbon materials are not always straightforward and depend on various factors, such as, type of defect, its density, surface morphology, porosity, surface area and activeness of surface defects. Furthermore, in case of hierarchically porous and three-dimensional (3D) carbon materials with abundant junctions between sp2 and sp3-hybridized carbon lattices, the understanding of catalytic and other physical properties is more difficult but important for advancement of energy storage technologies in 3 dimensions. We have opted different experimental techniques to fabricate different hierarchical carbon materials. We have grown vertically aligned few-layer graphene and carbon nanotubes (CNTs) to increase the intrinsic surface area of 3D structures. Moreover, we established an innovative technique to effectively functionalize those structures to provide active surface defects through heteroatoms (N, B) doping, for enhanced sorption based thermal energy recycling and electrochemical energy storage applications.
The active carbon surface demonstrated about 6-fold increase in methanol sorption enthalpy. We fabricated CNT, graphene and CNT-graphene hybrid-foams with ultra-low density (~4mg/cc) which showed ~200 % increased Li-ion storage capacity as binder-free anode. Vertically oriented CNTs grown on carbon-textiles and proper functionalization indicated high areal-capacitance of 107 mF/cm2 with excellent flexibility. We conducted experiments to understand and correlate the thermal transport and catalytic properties with structural details. The porosity is not always a dictating factor for thermal transport in 3D carbon structures rather the crystallinity and junctional properties determine the transport properties.