ORCID Profile
0000-0001-9389-7141
Current Organisations
Massachusetts Institute of Technology
,
Hong Kong University of Science and Technology
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Publisher: Wiley
Date: 24-03-2018
Publisher: American Chemical Society (ACS)
Date: 11-07-2018
Abstract: Hexagonal boron nitride (h-BN) has tremendous potential for dielectric energy storage by rationally assembling with graphene. We report the fabrication of microlaminate composites consisting of alternating reduced graphene oxide (rGO) and h-BN nanosheets embedded in a polyurethane (PU) matrix using a novel, two-step bidirectional freeze casting process. Porous, highly-aligned rGO-PU aerogels having ultrahigh dielectric constants with relatively high dielectric losses and low dielectric strengths are fabricated by initial freeze casting. The losses are suppressed, whereas the dielectric strengths are restored by assembling the porous rGO-PU skeleton with electrically insulating BN-PU tunneling barrier layers in the second freeze casting routine. The ligaments bridging the conductive rGO-PU layers are effectively removed by the BN-PU barrier layers, eliminating the current leakage in the transverse direction. The resultant rGO-PU/BN-PU microlaminate composites deliver a remarkable dielectric constant of 1084 with a low dielectric loss of 0.091 at 1 kHz. By virtue of synergy arising from both the rGO-PU layers with a high dielectric constant and the BN-PU barrier layers with a high dielectric strength, the microlaminate composites present a maximum energy density of 22.7 J/cm
Publisher: American Chemical Society (ACS)
Date: 10-2018
Abstract: Graphene aerogel (GA) has shown great promise as reinforcement of polymeric composites with exceptional electrical and mechanical characteristics. Although there has been significant progress in controlling the structure of GAs, no studies have appeared on the enhanced properties of GAs by employing high-quality precursor graphene flakes (GFs). However, the assembly of high-quality GFs is particularly challenging due to their highly hydrophobic and agglomerative nature in aqueous media, and of the few methods available to synthesize high-quality GFs, most produce flakes with very small lateral sizes. Herein, we report the fabrication of highly crystalline GAs using large nonoxidized graphene flakes (NOGFs) prepared by a novel graphite intercalation compound-based method. Bidirectional freeze casting is utilized for aligning NOGFs in two orthogonal directions, vertically and laterally, where the NOGF walls in idually function as effective conductive pathways. The as-prepared nonoxidized graphene aerogel (NOGA) exhibits a defect concentration as low as 1.4% of impurity oxygen with an excellent electrical conductivity of 202.9 S/m at a low density of 5.7 mg/cm
Publisher: American Chemical Society (ACS)
Date: 09-02-2018
Abstract: Unidirectional graphene aerogels (UGAs) with tunable densities, degrees of alignment, and electrical conductivities are prepared by varying the average size of precursor graphene oxide (GO) sheets between 1.1 and 1596 μm
Publisher: Elsevier BV
Date: 10-2017
Location: United States of America
No related grants have been discovered for Ne Myo Han.