Hongwei Zhu Tsinghua University, China
Dr. Zhu received his B.S. degree in Mechanical Engineering (1998) and Ph.D. degree in Materials Processing Engineering (2003) at Tsinghua University. After Post Doc. studies in Japan and USA, he began his independent career as a faculty member at Tsinghua University (2008~present). He is currently a Professor at the School of Materials Science and Engineering. His research interests involve macrostructure assembly and engineering of graphene and carbon nanotubes, flexible devices, sensors, and membranes for energy and environment related applications. He has authored 2 books and 6 invited book chapters, received 15 CN patents, 1 US patent and published 190+ papers in refereed international journals including Science, Adv. Mater., Nano Lett. with a H-index of 46 (citations > 8000).
Title：1.Graphene Oxide based Membranes for Potential Water Treatment Applications 2.Graphene-on-SemiconductorSchottky Junction
SymposiumDesalination & Solar Cells
Starting Time
Ending Time
Abstract
1.Recently, the investigation on the selective mass transport properties of graphene oxide (GO) based materials remains to be a hot topic [1]. Many novel mass transport properties in relation to the unique structure of GO have been revealed, which are not possible in the traditional membrane materials. This talk introduces the latest advances in our group, including experimental discoveries and theoretical results, on the novel mass transportation through GO membranes.
A hybrid membrane consisting of anionic GO and cationic layered double hydroxide (LDH) nanosheet superlattice units is designed (Fig. 1) and prepared for high selectivity charge-guided ion transport [2]. The interlayer spacing of the hybrid membrane is insensitive to humidity variations, ensuring the structural stability insolution-based mass transport. The concentration gradient-driven ion transmembrane diffusion experiments show that the cations bearing various valences can be effectively separated strictly according to their charges, independent of the cationic and charge-balancing anionic species. A synergistic effect originating from the molecular-level heteroassembly of GO and LDH plays a dominant role in the high-performance charge-guided ion filtration and separation processes. The relative selectivity toward monovalent and trivalent cations is as high as 30.
A combined experimental and molecular dynamics simulations study further shows that intrinsic high water/ion selectivity of GO membranecan be achieved in concentration gradient-driven diffusion, showing great promises in water desalination [3], while in pressure-driven filtration the salt rejection is poor. This study unveils a long-overlooked reason behind the controversy in water desalination with GO membranes and provides a fundamental understanding on the in-depth mechanism concerning the strong correlation of water/ion selectivity with the applied pressure and GO nanochannel length. The applied pressure weakens the water-ion interactions in GO nanochannel and reduces their permeation selectivity, while the length of nanochannel dominates the mass transport processes and the ion selectivity.
2.Recently, the advances and breakthroughs of graphene materials have been witnessed in both scientific fundamentals and potential applications. In this talk, we discuss one of the simplest building blocks for a graphene-based electronics: a layer of graphene atop a semiconductor, whose contact forms the so-called Schottky junction.
The content discussed here may enable researchers to better understand the photoelectric effect of graphene-semiconductor junctions and to optimize the design of graphene-based photodevices for a wide range of applications. This simple modelis expected to play a great role in particular field to realize multi-function integrated portable or lightweight thin-film products, such as energy harvest for smart-phone, wearable-device, and even medical-monitor in the future.For a more comprehensive treatment of the topic see reference.
Follow us on WeChat
京公网安备 11010802030754号