Physical Chemistry Seminar: Professor Tianquan (Tim) Lian, University of Pennsylvania
About the Seminar
"Electrochemical Control of Static and Ultrafast Electrode-Induction Effects: from electrochemical Stark effect to plasmon-driven mode-selective adsorbate excitation"
Attaching molecular catalysts on (photo-) electrodes offers a promising approach for modular and rational design of hybrid catalysts for (photo-) electrochemical transformations. The design and improvement of such hybrid catalysts require fundamental understanding of the structure and microenvironment of catalysts, interfacial field, and adsorbate-electrode interaction as well as their effects on adsorbate/catalysts excited state dynamics. To probe these electrode-adsorbate interactions at the molecular level, we have been developing and applying time-resolved vibrational sum frequency generation (VSFG) spectroscopy and surface enhanced Raman spectroscopy (SERS) as in situ interface specific/sensitive vibrational spectroscopic tools. In this talk, I will discuss two recent studies in this area. 1) We have observed surprisingly large electrochemical-Stark effect of adsorbed molecules and molecular CO2 reduction catalysts. We demonstrated that the Stark-effect is dominated by through bond interaction of the electrode on the adsorbates (i.e. the electrode induction effect), and this result suggests a potential new approach for design and control of catalysts. 2) Using time-resolved SERS, we directly observe plasmon-driven mode-selective adsorbate vibrational excitation caused by strong adsorbate-metal interaction (i.e. the dynamic electrode induction effect). This finding suggests possible electrochemical control of photocatalysis on plasmonic metal surface and/or light-enhanced electrocatalysis.
About the Speaker
Tianquan (Tim) Lian received BS degree from Xiamen University in China in 1985, MS degree from Fujian Institute of Research on the Structure of Matter (with Prof. Hongyuan Shen) in 1988 and PhD degree from University of Pennsylvania (with Prof. Robin Hochstrasser) in 1993. After postdoctoral training in the University of California at Berkeley (with Prof. Charles B. Harris), he joined the faculty of chemistry department at Emory University in 1996, where he was promoted to Associate Professor in 2002, Full Professor in 2005 and William Henry Emerson Professor of Chemistry in 2008. In August 2025, Tim Lian joined the Department of Chemistry and Vagelos Institute of Energy Science and Technology of the University of Pennsylvania as the John H. and Margaret B. Fassitt Professor of Chemistry. Tim Lian serves as the Editor-in-Chief of the Journal of Chemical Physics since Jan. 1, 2019 and has been the recipient of a few notable recognitions, including NSF CAREER award, Alfred P. Sloan fellowship, Kavli Frontier of Science fellow, APS fellow, ACS PChem Division Award for Senior Experimental Physical Chemistry, and AAAS Fellow. Tim Lian’s research is focused on developing and applying advanced in situ ultrafast and nonlinear spectroscopy tools to enable direct probe of interfacial structure, dynamics, and reaction mechanisms in nanomaterials and on electrodes and photoelectrodes and to advance the understanding of fundamental problems in energy conversion.