污污草莓视频

Abstract:

For the past century and more, physical chemists and chemical physicists have sought to understand chemical reactivity in terms of underlying physical processes. This fruitful connection has led to great breakthroughs in conceptual understanding and practical application for fostering and controlling chemical reactions. Here, we examine how the physical principles of solid mechanics and topological physics can influence surface chemistry.

Mechanochemistry: The field of mechanochemistry is presently experiencing a renaissance. The governing hypothesis of this field is that force and stress (delivered by adjacent materials) can open novel avenues of chemical reactivity. In this context, we recently developed methodologies to relate applied pressure to molecular chemical transformations. More recently, we have examined the chemical consequences of bending nanomaterials. This deformation rearranges electronic states spatially, creating new opportunities for chemical reaction. Following this paradigm, we demonstrated that molecules bonded to curved graphene will definitively move, with the direction of movement controlled by the sign of the curvature and the type of molecular bonding. We also explored the strain-driven water decomposition on graphene as a model system to investigate the influence of mechanical distortions on 2D materials.

Topological physics: Over the past twenty years, physicists have come to appreciate that the band structures of crystals can have different connectivities in momentum space, and some of these connectivities (鈥渢opologically nontrivial鈥�) are not adiabatically connected to isolated connections of atoms or molecules. Thus, in some deep ways, the band topology encodes the nature of the chemical bonding in materials, leading to novel, potentially chemically active, edge states. In this area, we predicted novel topological band features, which have been experimentally realized. More recently, we have developed theoretical insights into how specific topological surface behaviors can be related to catalytic enhancements of energy-relevant chemical reactions.

These findings provide new avenues for the manipulation of molecular motions and chemical interactions via mechanical deformations of various two-dimensional materials and the exploration of surfaces in topologically novel materials, broadening the palette of physical phenomena that can beneficially impact surface chemical reactivity.

The authors acknowledge the support of the NSF through grant CHE-2303044 and the DOE through grant DE-SC0024942, as well as computational support from NERSC.

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Bio:

Andrew M. Rappe is Blanchard Professor of Chemistry and Professor of Materials Science and Engineering at the University of Pennsylvania. He received his A.B. in 鈥淐hemistry and Physics鈥� summa cum laude from Harvard University in 1986, and his Ph.D. in 鈥淧hysics and Chemistry鈥� from MIT in 1992. He was an IBM Postdoctoral Fellow at UC Berkeley before starting at Penn in 1994.

Andrew received an NSF CAREER award in 1997, an Alfred P. Sloan Research Fellowship in 1998, and a Camille Dreyfus Teacher-Scholar Award in 1999. He was named a Fellow of the American Physical Society in 2006.

Rappe was named Weston Visiting Professor at the Weizmann Institute of Science in 2014, and Ziqiang Professor at Shanghai University in 2016. He was awarded the Humboldt Research Award in 2017 and the Cheney Fellowship at University of Leeds in 2018.

Andrew is one of two founding co-directors of the VIPER honors program at Penn, the Vagelos Integrated Program in Energy Research.

Andrew has published more than 300 peer-reviewed articles. In recent years, he has become a leader in the theory of hybrid organic-inorganic perovskites and of topological materials. He has championed the use of the bulk photovoltaic effect for solar energy harvesting, and he has made seminal contributions to the theory of ferroelectric materials and to topological physics. In the field of electrochemistry, Rappe studies how nonstoichiometric surfaces, smart material substrates, and anomalous light-matter interactions yield electrocatalysts with breakthrough activity and selectivity for hydrogen evolution, oxygen evolution, and CO₂ reduction reactions.