Nanyang Technological University

About: Nanyang Technological University is a education organization based out in Singapore, Singapore. It is known for research contribution in the topics: Computer science & Catalysis. The organization has 48003 authors who have published 112815 publications receiving 3294199 citations. The organization is also known as: NTU & Universiti Teknologi Nanyang.

High-performance flexible asymmetric supercapacitors based on a new graphene foam/carbon nanotube hybrid film

Abstract: In this work, we report the fabrication of a new 3D graphene foam (GF)/carbon nanotube (CNT) hybrid film with high flexibility and robustness as the ideal support for deposition of large amounts of electrochemically active materials per unit area. To demonstrate the concept, we have deposited MnO2 and polypyrrole (Ppy) on the GF/CNT films and successfully fabricated lightweight and flexible asymmetric supercapacitors (ASCs). These ASCs assembled from GF/CNT/MnO2 and GF/CNT/Ppy hybrid films with high loading of electroactive materials in an aqueous electrolyte are able to function with an output voltage of 1.6 V, and deliver high energy/power density (22.8 W h kg−1 at 860 W kg−1 and 2.7 kW kg−1 at 6.2 W h kg−1). The rate performance can be further improved with less loading of electroactive materials (10.3 kW kg−1 at 10.9 W h kg−1). The ASCs demonstrate remarkable cycling stability (capacitance retention of 90.2–83.5% after 10 000 cycles), which is among the best reported for ASCs with both electrodes made of non-carbon electroactive materials. Also the ASCs are able to perfectly retain their electrochemical performance at different bending angles. These ASCs demonstrate great potential as power sources for flexible and lightweight electronic devices.

Raman spectroscopy of epitaxial graphene on a SiC substrate

Abstract: The fabrication of epitaxial graphene (EG) on SiC substrate by annealing has attracted a lot of interest as it may speed up the application of graphene for future electronic devices The interaction of EG and the SiC substrate is critical to its electronic and physical properties In this work, the Raman spectroscopy was used to study the structure of EG and its interaction with SiC substrate All the Raman bands of EG blueshift from that of bulk graphite and graphene made by micromechanical cleavage, which was attributed to the compressive strain induced by the substrate A model containing $13\ifmmode\times\else\texttimes\fi{}13$ honeycomb lattice cells of graphene on carbon nanomesh was constructed to explain the origin of strain The lattice mismatch between graphene layer and substrate causes the compressive stress of $227\phantom{\rule{03em}{0ex}}\mathrm{GPa}$ on graphene We also demonstrate that the electronic structures of EG grown on Si- and C-terminated SiC substrates are quite different Our experimental results shed light on the interaction between graphene and SiC substrate, which are critical to the future applications of EG

Layered transition metal dichalcogenides for electrochemical energy generation and storage

Abstract: Layered transition metal dichalcogenides (TMDs) (MoS2, MoSe2, WS2, WSe2, etc.) are a chemically diverse class of compounds having band gaps from 0 to ∼2 eV and remarkable electrochemical properties. The band gaps and electrochemical properties of TMDs can be tuned by exchanging the transition metal or chalcogenide elements. After a brief description of the most commonly followed synthetic routes to prepare TMDs, we wish to highlight in this review the diverse electrochemical applications of MoS2, a representative and well-studied TMD, which range from its use as catalysts in hydrogen evolution reactions to its adoption in supercapacitors, batteries, solar cells, and hydrogen storage.