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Pitt research team’s discovery of new nanomaterial behavior featured on cover of American Chemical Society journal

“Au13: CO Adsorbs, Nanoparticle Responds”

PITTSBURGH (August 13, 2015) … Researchers at the University of Pittsburgh Swanson School of Engineering discovered new insights into nanoscale phenomena that provide a greater understanding of the overall functionality of nanoparticles. Their paper, "Au13: CO Adsorbs, Nanoparticle Responds," appeared on the cover of the American Chemical Society's publication Journal of Physical Chemistry C (volume 119, issue 32, DOI: 10.1021/acs.jpcc.5b03459) on August 13.

Giannis Mpourmpakis, assistant professor of chemical and petroleum engineering, served as principal investigator, and graduate student researcher Natalie Austin and J. Karl Johnson, professor of chemical and petroleum engineering, co-authored the paper. The researchers found an unexpected adsorption, or adhesion, behavior of carbon monoxide (CO) molecules on Au13 nanoparticles-clusters containing exactly 13 gold atoms.

Unlike the well-established, size-dependent adsorption trend on nanoparticles (CO binding increases with decreasing nanoparticle size), Au13 exhibited shape-dependent behavior when binding to the CO molecules. A 3-dimensional Au13 nanoparticle is generated from the 2-dimensional stable structure in the presence of CO molecules. Interestingly, Mpourmpakis said, the 3-dimensional Au13 nanoparticle binds stronger the CO molecules than the 2-dimensional structure, which is lacking bonds on its surface.

"The binding of molecules to metal surfaces is critically important because it is the basic first step in all catalytic processes," Mpourmpakis said. "This is critical to produce the building blocks for almost all manufactured products."

The unusual behavior is the result of quantum electronic effects at the nanoscale, which dictate how electrons are distributed on the nanoparticles having different shapes. The research team used atomically-detailed computer simulations to reveal the behavior of Au13 adsorption.

"Our simulations showed that in the presence of CO, the 2-dimensional Au13 nanoparticle restructured to a 3-dimensional structure on an incredibly short time scale of just a few picoseconds (trillionths of a second)," added Johnson, who is also co-director of Pitt's Center for Simulation and Modeling.

In their paper, the authors highlighted that other computer simulations can unravel very complicated phenomena at the nanoscale including molecular adsorption and structural dynamics of nanoparticles in a chemical environment. The understanding of these phenomena determines, to a large extent, the overall functionality of nanoparticles, including in catalysis, chemical sensing, medical devices, optical materials, and other applications.

Mpourmpakis leads his team in the Computer-Aided Nano and Energy Lab (C.A.N.E.LA.) at the University of Pittsburgh. Using theory and computation, the researchers investigate the physicochemical properties of nanomaterials with potential applications in diverse nanotechnological areas, ranging from green energy and storage to materials engineering and catalysis.

The Center for Simulation and Modeling (SaM) at the University of Pittsburgh is dedicated to supporting and facilitating computational-based research across campus. SaM serves as a catalyst for multidisciplinary collaborations among professors, sponsors modeling-focused seminars, teaches graduate-level modeling courses and provides individual consultation in modeling to all researchers at the University. Its areas of research include: energy and sustainability, nanoscience and materials engineering, medicine and biology, and economics and the social sciences.

About the Department of Chemical and Petroleum Engineering

The Department of Chemical and Petroleum Engineering serves undergraduate and graduate engineering students, the University and our industry, through education, research, and participation in professional organizations and regional/national initiatives. Our commitment to the future of the chemical process industry drives the development of educational and research programs. The Department has a tradition of excellence in education and research, evidenced by recent national awards including numerous NSF CAREER Awards, a Beckman Young Investigator Award, an NIH Director's New Innovator Award, and the DOE Hydrogen Program R&D Award, among others. Active areas of research in the Department include Biological and Biomedical Systems; Energy and Sustainability; and Materials Modeling and Design. The faculty has a record of success in obtaining research funding such that the Department ranks within the top 25 U.S. ChE departments for Federal R&D spending in recent years with annual research expenditures exceeding $7 million. The vibrant research culture within the Department includes active collaboration with the adjacent University of Pittsburgh Medical Center, the Center for Simulation and Modeling, the McGowan Institute for Regenerative Medicine, the Mascaro Center for Sustainable Innovation, the Petersen Institute of NanoScience and Engineering and the U.S. DOE-affiliated Institute for Advanced Energy Solutions.

Author: Paul Kovach

Contact: Paul Kovach