Topic: Plasmon-induced hot electron transfer to semiconductor and molecular acceptors
Speaker: Professor Lian Tianquan (Tim), Department of Chemistry, Emory University (Emory)
Date and time: May 13, 9:30–11:00
Venue: Room 105, #5 Building of SPST
Host: Liu Weimin
Abstract:
In plasmonic hot carrier photocatalysis, plasmon excitation in metal nanostructures drives catalytic reactions by transferring hot electrons and/or holes to semiconductors or adsorbed molecules. However, reported quantum efficiencies are often low, hindering process improvement. In this talk, we will discuss our recent progress in understanding plasmon-induced hot electron transfer at the plasmonic metal/semiconductor and metal/adsorbate interface.
In the first part, we discuss approaches to enhance plasmon-induced hot electron transfer efficiency at metal/semiconductor interfaces. Using CdS/Au nanorods, we demonstrate increased hot electron injection efficiency at smaller Au particle sizes. Additionally, in CdSe/Au heterostructures with strong metal/semiconductor coupling, plasmondecay occurs through direct excitation of an electron from the metal to semiconductor, known as plasmon-induced interfacial charge transfer transition (PICTT). Combining these approaches achieves highly efficient (>50%) plasmon-induced hot electron transfer from small Ag nanoparticles to TiO2.
In the second part, we discuss our recent effort to probe the effect of hot electron transfer on adsorbate vibrational dynamics at plasmon/adsorbate interfaces using in situ electrochemical time-resolved vibrational sum-frequency generation (SFG) spectroscopy. Excitation of the metal leads to vibrationally excited CO molecules adsorbed on Au electrodes, indicating direct coupling of adsorbate vibration modes with hot electrons. Ongoing studies systematically examine how the hot electron transfer process depends on electrode, adsorbate, and applied bias conditions.
Biography:
Lian Tianquan (Tim) received BS degree from Xiamen University in China in 1985, MS degree from Fujian Institute of Research on the Structure of Matter (under the supervision of Prof. Shen Hongyuan) in 1988 and PhD degree from University of Pennsylvania (under the supervision of late Prof. Robin Hochstrasser) in 1993. After postdoctoral training with late Prof. Charles B. Harris at the University of California, Berkeley, Lian joined the faculty of chemistry department at Emory University in 1996, where he was promoted to Associate Professor in 2002, Full Professor in 2005, Winship Distinguished Research Professor in 2007, and William Henry Emerson Professor of Chemistry in 2008. Lian is currently the Editor-in-Chief of the Journal of Chemical Physics (since Jan. 1, 2019). He is the recipient of a few notable recognitions, including NSF CAREER award, Alfred P. Sloan Fellowship, Kavli Frontier of Science Fellow (since 2012), APS Fellow (since 2015), ACS PChem Division Award for Senior Experimental Physical Chemistry (2022), and AAAS Fellows. Lian’s research interest is focused on in situ probe of the interfacial structure, dynamics, and reaction mechanisms in nanomaterials and electrochemical and photoelectrochemical devices.