Chemistry's Zhongyu Liu Receives IPMI Student Award
By Amy Pavlak Laird
Media Inquiries- Interim Director of Communications, MCS
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Chemistry Ph.D. student Zhongyu Liu has received the 2024 Bureau Veritas Student Award from the International Precious Metals Institute (IPMI) for his work on the photoluminescence of ultrasmall gold nanoclusters. He will receive the $5,000 award at the IPMI's annual conference in June.
Liu's research focuses on atomically precise gold nanoclusters made of only dozens of atoms. These nanosized particles have unique optical, electrical and magnetic properties. Of particular interest to Liu is their photoluminescence.
"Gold nanoclusters are very special materials with intriguing optical properties," Liu said. "What interests me is understanding their unique emission range and how to manipulate their emission intensity."
By manipulating the nanoclusters' size, structure and composition, they can be tuned to emit wavelengths from the visible to the near-infrared regions of the electromagnetic spectrum. Developing molecules that emit in the near-infrared offers advantages in a variety of biomedical imaging applications. Unlike visible light, near-infrared wavelengths can penetrate tissues more deeply owing to much less absorption by biological tissue and dramatically improve the image resolution by minimizing the biological tissue's autofluorescence and optical scattering backgrounds.
Since joining Chemistry Professor Rongchao Jin's group in 2019, Liu has worked to understand the mechanism behind the near-infrared photoluminescence of gold nanoclusters, including Au25(SR)18 — a nanocluster with 25 gold atoms surrounded by a ligand shell. He developed a physical model to explain how nanocluster vibrations quenched the luminescence. From there, he designed a strategy to significantly boost the photoluminescence quantum yield, which was a thrilling discovery, according to Jin.
His work on Au25 was especially rewarding for Liu.
"It had been a decade-long question: why is this nanocluster emissive and what is its true emission spectrum? Our research finally determined its full range emission spectrum."
Liu has published his research in several journals, including the Journal of the American Chemical Society, ACS Nano, Advanced Materials and the Journal of Physical Chemistry Letters. Several more research publications are in progress.
"Zhongyu's work on the photoluminescence of atomically precise gold nanoclusters is highly impactful in both fundamental research and practical applications for bio-imaging," Jin said. "He has carried out exceptional physical chemistry research, and I'm sure he will make more discoveries."
After graduation, Liu will continue his research as a postdoctoral fellow at Stanford University. There he plans to continue investigating gold nanoclusters for use in bioimaging and cancer therapy.
IPMI is the international trade association for the precious metals industry representing producers, refiners, fabricators, recyclers, users, financial institutions, merchants, scientists, private and public sector groups and the general precious metals community. IPMI's Educational and Scientific Foundation recognizes excellence and achievement through student and institutional awards.