Khalifa University
Prof. Lianxi Zheng received his BE degree on Electronic Engineering from Southeast University (China), and his Ph.D. on Physics from The University of Hong Kong. He has worked in Los Alamos National Laboratory as a director’s postdoctoral fellow, CNT Technologies Inc. as a research scientist, Nanyang Technological University as an assistant professor, and now is an full professor in Khalifa University (UAE). Prof. Zheng is working in the interdisciplinary fields of material sciences and nanotechnologies, with emphasis on low dimensional nanomaterials and their functional applications, including energy harvest & storage devices, photocatalysis, optoelectronics, nano-composites, e-textile, and smart sensors. During his career, he has received several awards including 2 Nano 50 Award from NASA, licensed 3 US patents, and published more than 150 papers in high quality journals such as Nature Materials, Materials Today, Advanced Materials, Physical Review Letters etc.
Two of the biggest challenges confronting the world today are the global crises of clean energy supply and environmental pollution. To address these concerns, one of the most promising and sustainable technologies is sunlight assisted semiconductor-based photocatalysis, which uses free solar energy to produce clean energy and for the removal of environmental pollutants. Here, Adsorption-enhanced photodegradation and its unique photocatalytic kinetics are studied in a bifunctional 2D/2D Z-Scheme photocatalyst. The MoS2 nanoflakes are selectively deposited on the edges of TiO2 nanosheets to form an edge-connected MoS2/Au/TiO2 Z-scheme heterostructured photocatalyst, with 2D MoS2 as a strong adsorbent to reduce the pollutants rapidly and TiO2 as a photocatalyst for subsequent degradation. The resultant structure not only takes advantage of the combinative effect from the facet junction and heterojunction to maximize the charge separation and form a Z-scheme structure, but also physically separates the redox reactive surfaces, leaving the highly-exposed (001) facets of 2D TNSs for oxidation and maintains the surface reactivity for effective bifunctions. As a result, the designed system removes 90% of pollutant within 30 mins and subsequently eliminates the residue to a level below ppm. Detailed study on the synergistic effects of adsorption and photodegradation indicates that the system exhibits an adsorption-enhanced photodegradation due to the pre-concentration effect by MoS2 and a surface-diffusion mechanism of pollutant molecules migrating from MoS2 to TiO2. This work provides a novel strategy in designing the bifunctional photocatalyst for effective water treatment.
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