Curtis successfully passed his B-exam today, wrapping up his years at Cornell. Impressive presentation, great weather, perfect for a celebration. Good luck at Dow-Dupont, and congratulations!
Tobias has been promoted to Full professor. The decision is based on reviews of students, colleagues and international peers, and highlights his commitment to teaching, mentoring, motivating students and redesigning educational approaches. We, the lab members couldn’t agree more. Congratulations!
Dr. Daniel Balazs and Eliad Peretz will attend the 69th Lindau Nobel Laureate Meeting taking place from 30 June to 05 July 2019 in Lindau, Germany (https://www.lindau-nobel.org/).
For years, scientists have been trying to discover the size at which solid materials could change their internal structure in a single, swift step, like molecules do during isomerization. This unanswered question has been the missing link in scientists’ quest to map and understand the crossover from molecular isomerization, such as those that make eyesight possible, to bulk phase transitions, like the transition of graphite into diamonds. If understood, these processes could be useful for applications such as energy harvesting or quantum computing. In their recent paper published in Science (DOI: 10.1126/science.aau9464), Professors Tobias Hanrath and Richard Robinson finally reveal that a “magic size cluster” bridges this divide between how matter rearranges in the small scale of molecular isomerization and in large, solid bulk matter phase transitions.
Here is a link to the Cornell Chronicle article
and the Science article,
Ben’s work on the mechanistic details of growing nanowires on heated copper surfaces is published in Chemistry of Materials. The work discusses the thermodynamics of the seed formation, and shows a beautiful, simple method to study the process in situ. Read the paper HERE.
The CANFI (continuous additive nanomanufacturing at fluid interfaces) team won a commercialization and scale-up grant from the college of engineering.
Rileigh Casebolt and Jesus Miguel Lopez Baltazar join the group. Rileigh will be working on electrochemical CO2 reduction and Jesus will work on programmable assembly (in collaboration with Prof. Alabi)
Congratulations, Dr. Richards! for successfully defending your PhD thesis. Pictures from the defense and abstract of the presentation are below.
Bulk-nucleated vapor-solid-solid Silicon and Germanium Nanowires: Synthesis, Scaling, and Applications
Benjamin T. Richards
Cornell University, 2018
Nanowires are essential building blocks for many next-generation devices. This includes applications in solar cells, field effect transistors, thermoelectric generators, chemical sensors, and electrochemical cells. One application of intense promise is using silicon and germanium nanowires as anodes materials in lithium ion batteries, as these materials form stable compounds with superior lithium capacity that increases the anode charge capacity compared to current Li-ion batteries by a factor of 4 – 10. Unlike the bulk material, nanowires have been demonstrated to withstand the ~400% volume dilation due to the intercalation of lithium. To bring the acclaimed potential of nanowires to fruition, challenges in production, scaling, and electrochemical performance must be resolved. Conventional nanowire synthesis methods produce small yields of nanowires that require many processes (i.e., slurry mixing, coating, baking) to introduce into batteries. To meet the growing energy storage demands for personal electronics and electric vehicles, an improved method is required to produce nanowires.
In this work, I will introduce a growth mechanism that is simple, robust, and adaptable to high throughput processing of nucleating and growing nanowires from bulk metal films, known as bulk nucleated vapor-solid-solid (BN-VSS). This method prepares nanowires that are epitaxially connected to the metal substrate, allowing direct integration into batteries. I identify the kinetic conditions required to grow nanowires, the processes that occur during nanowire growth, and copper as a promising growth substrate material. Then, I will present a kinetic model of germanium nanowire growth from copper films using diphenylgermane as a precursor. This model was developed by performing rapid syntheses of nanowires using an inductive heating apparatus followed by ex-situ characterization of these films. Finally, I introduce a diagnostic technique of measuring the electrical resistance of the growth substrate to monitor the solid-state transformation that proceeds to germanium nanowire growth and demonstrate how this method can be used to inform kinetic conditions in high-throughput roll-to-roll reactors.