题目：Landscape of TMDs: from synthesis to electrochemical electronics
报告人：Prof. Liu Zheng（Nanyang Technological University, Singapore）
Two-dimension (2D) transition-metal dichalcogenides (TMDs) have recently provided a rich source of research opportunity, revealing interesting physical phenomena including quantum-spin Hall effect (QSH), valley polarization, 2D superconductivity, and potential applications for functional devices. Here, we demonstrate that molten salt-assisted chemical vapor deposition can be broadly applied for the synthesis of a wide variety of 2D TMDs . We demonstrate the synthesis of 47 compounds, including 32 binary, 13 alloys, and 2 heterostructured compounds. We elaborate the general growing mechanism of this method, demonstrating that the salt decreases the melting point of reactants and facilitates the formation of intermediate products.
Based on the 2D materials, we have recnelty revisited the semiconductor-electrolyte interface and unraveled a universal self-gating phenomenon through micro-cell based in-situ electronic/electrochemical measurements . We unveiled a surface conductance mechanism under self-gating that dominates the charge transport in semiconductor electrocatalysts, and demonstrate the strong correlation between them. Then we demonstrate that the type of semiconductor catalysts strongly correlates and their electrocatalysis, i.e., n-type semiconductor catalysts favor cathodic reactions such as hydrogen evolution reaction (HER), p-type ones prefer anodic reactions such as oxygen evolution reaction (OER), and bipolar ones tend to perform both anodic and cathodic reactions. Our study provides a new insight into the electronic origin of semiconductor-electrolyte interface during electrocatalysis, paving the way for designing high-performance semiconductor catalysts.
Dr. Zheng LIU is currently an associate professor in Nanyang Technological University, Singapore. He works on following topics: 1) Synthesis of high-quality and large-size novel 2D monolayers, especially, transition metal dichalcogenides (TMDs); 2) Engineering of 2D materials such as lateral/vertical 2D heterostructure and alloy; 3) Physical properties of 2D monolayers such as 2D superconductivity, 2D ferroelectricity, 2D ferromagnetism and 2D Wyle semi-metals; 3) Applications of 2D materials such as novel semiconducting electronics. He has published > 190 papers including 28 papers in Nature and Science serial journals; 26 in Adv Mater; 24 in Nano Lett; 16 in ACS Nano, 4 in JACS, with total citations > 20,000 and H-index of 66 (GoS, as to 1 June 2019). He was the finalist of the World Technology Award in Energy category in 2012. In 2013, he was awarded the prestigious Singapore NRF Fellowship and the elite Nanyang Assistant Professorship. He was awarded ICON-2DMAT Young Scientist Award and the prestigious Singapore Young Scientist Award in 2018. He was highly cited researcher in 2018 in the category of Materials Science. He was named Materials Research Society of Singapore Chair in 2019.