Nanotechnology Now

Our NanoNews Digest Sponsors
Heifer International



Home > Press > Rice lab peers inside 2D crystal synthesis: Simulations could help molecular engineers enhance creation of semiconducting nanomaterials

Three gas-phase molecules react at high temperatures during chemical vapor deposition to form molybdenum disulfide, a two-dimensional semiconductor that could find use in next-generation electronics. In this illustration, molybdenum atoms are purple, oxygen is red and sulfur is yellow. (Credit: Illustration by Jincheng Lei/Rice University)
Three gas-phase molecules react at high temperatures during chemical vapor deposition to form molybdenum disulfide, a two-dimensional semiconductor that could find use in next-generation electronics. In this illustration, molybdenum atoms are purple, oxygen is red and sulfur is yellow. (Credit: Illustration by Jincheng Lei/Rice University)

Abstract:
Scientific studies describing the most basic processes often have the greatest impact in the long run. A new work by Rice University engineers could be one such, and it’s a gas, gas, gas for nanomaterials.



An animation by Rice University engineers shows the incorporation of MoS6 into a crystal lattice of molybdenum disulfide. (Credit: Yakobson Research Group/Rice University)

Rice lab peers inside 2D crystal synthesis: Simulations could help molecular engineers enhance creation of semiconducting nanomaterials

Houston, TX | Posted on June 11th, 2021

Rice materials theorist Boris Yakobson, graduate student Jincheng Lei and alumnus Yu Xie of Rice’s Brown School of Engineering have unveiled how a popular 2D material, molybdenum disulfide (MoS2), flashes into existence during chemical vapor deposition (CVD).

Knowing how the process works will give scientists and engineers a way to optimize the bulk manufacture of MoS2 and other valuable materials classed as transition metal dichalcogenides (TMDs), semiconducting crystals that are good bets to find a home in next-generation electronics.

Their study in the American Chemical Society journal ACS Nano focuses on MoS2’s “pre-history,” specifically what happens in a CVD furnace once all the solid ingredients are in place. CVD, often associated with graphene and carbon nanotubes, has been exploited to make a variety of 2D materials by providing solid precursors and catalysts that sublimate into gas and react. The chemistry dictates which molecules fall out of the gas and settle on a substrate, like copper or silicone, and assemble into a 2D crystal.

The problem has been that once the furnace cranks up, it’s impossible to see or measure the complicated chain of reactions in the chemical stew in real time.

“Hundreds of labs are cooking these TMDs, quite oblivious to the intricate transformations occurring in the dark oven,” said Yakobson, the Karl F. Hasselmann Professor of Materials Science and NanoEngineering and a professor of chemistry. “Here, we’re using quantum-chemical simulations and analysis to reveal what’s there, in the dark, that leads to synthesis.”

Yakobson’s theories often lead experimentalists to make his predictions come true. (For example, boron buckyballs.) This time, the Rice lab determined the path molybdenum oxide (MoO3) and sulfur powder take to deposit an atomically thin lattice onto a surface.

The short answer is that it takes three steps. First, the solids are sublimated through heating to change them from solid to gas, including what Yakobson called a “beautiful” ring-molecule, trimolybdenum nonaoxide (Mo3O9). Second, the molybdenum-containing gases react with sulfur atoms under high heat, up to 4,040 degrees Fahrenheit. Third, molybdenum and sulfur molecules fall to the surface, where they crystallize into the jacks-like lattice that is characteristic of TMDs.

What happens in the middle step was of the most interest to the researchers. The lab’s simulations showed a trio of main gas phase reactants are the prime suspects in making MoS2: sulfur, the ring-like Mo3O9 molecules that form in sulfur’s presence and the subsequent hybrid of MoS6 that forms the crystal, releasing excess sulfur atoms in the process.

Lei said the molecular dynamics simulations showed the activation barriers that must be overcome to move the process along, usually in picoseconds.

“In our molecular dynamics simulation, we find that this ring is opened by its interaction with sulfur, which attacks oxygen connected to the molybdenum atoms,” he said. “The ring becomes a chain, and further interactions with the sulfur molecules separate this chain into molybdenum sulfide monomers. The most important part is the chain breaking, which overcomes the highest energy barrier.”

That realization could help labs streamline the process, Lei said. “If we can find precursor molecules with only one molybdenum atom, we would not need to overcome the high barrier of breaking the chain,” he said.

Yakobson said the study could apply to other TMDs.

“The findings raise oftentimes empirical nanoengineering to become a basic science-guided endeavor, where processes can be predicted and optimized,” he said, noting that while the chemistry has been generally known since the discovery of TMD fullerenes in the early ’90s, understanding the specifics will further the development of 2D synthesis.

“Only now can we ‘sequence’ the step-by-step chemistry involved,” Yakobson said. “That will allow us to improve the quality of 2D material, and also see which gas side-products might be useful and captured on the way, opening opportunities for chemical engineering.”

The Department of Energy Basic Energy Sciences program supported the research, and computations were performed at the National Energy Research Scientific Computing Center.

####

About Rice University
Located on a 300-acre forested campus in Houston, Rice University is consistently ranked among the nation’s top 20 universities by U.S. News & World Report. Rice has highly respected schools of Architecture, Business, Continuing Studies, Engineering, Humanities, Music, Natural Sciences and Social Sciences and is home to the Baker Institute for Public Policy. With 3,978 undergraduates and 3,192 graduate students, Rice’s undergraduate student-to-faculty ratio is just under 6-to-1. Its residential college system builds close-knit communities and lifelong friendships, just one reason why Rice is ranked No. 1 for lots of race/class interaction and No. 1 for quality of life by the Princeton Review. Rice is also rated as a best value among private universities by Kiplinger’s Personal Finance.


Follow Rice News and Media Relations via Twitter @RiceUNews.

For more information, please click here

Contacts:
Jeff Falk
713-348-6775


Mike Williams
713-348-6728

Copyright © Rice University

If you have a comment, please Contact us.

Issuers of news releases, not 7th Wave, Inc. or Nanotechnology Now, are solely responsible for the accuracy of the content.

Bookmark:
Delicious Digg Newsvine Google Yahoo Reddit Magnoliacom Furl Facebook

Related Links

Read the abstract at:

Yakobson Research Group:

Department of Materials Sciences and NanoEngineering:

George R. Brown School of Engineering:

Related News Press

2 Dimensional Materials

Buckyballs on gold are less exotic than graphene July 22nd, 2022

At the water’s edge: Self-assembling 2D materials at a liquid–liquid interface: Scientists find a simple way to produce heterolayer coordination nanosheets, expanding the diversity of 2D materials July 22nd, 2022

News and information

Biology’s hardest working pigments and ‘MOFs’ might just save the climate: A range of processes that currently depend on fossil fuels but are really hard to electrify will depend on the development of genuinely clean fuels, and for that to happen, much more efficient catalysts wi July 22nd, 2022

Generating power where seawater and river water meet July 22nd, 2022

First electric nanomotor made from DNA material: Synthetic rotary motors at the nanoscale perform mechanical work July 22nd, 2022

Videos/Movies

Scientists prepare for the world’s smallest race: Nanocar Race II March 18th, 2022

Visualizing the invisible: New fluorescent DNA label reveals nanoscopic cancer features March 4th, 2022

OCSiAl receives the green light for Luxembourg graphene nanotube facility project to power the next generation of electric vehicles in Europe March 4th, 2022

Nanotube fibers stand strong -- but for how long? Rice scientists calculate how carbon nanotubes and their fibers experience fatigue December 24th, 2021

Govt.-Legislation/Regulation/Funding/Policy

UNC Charlotte-led team invents new anticoagulant platform, offering hope for advances for heart surgery, dialysis, other procedures July 15th, 2022

Strain-sensing smart skin ready to deploy: Nanotube-embedded coating detects threats from wear and tear in large structures July 15th, 2022

Rensselaer researchers learn to control electron spin at room temperature to make devices more efficient and faster: Electron spin, rather than charge, holds the key July 15th, 2022

Crystal phase engineering offers glimpse of future potential, researchers say July 15th, 2022

Possible Futures

Biology’s hardest working pigments and ‘MOFs’ might just save the climate: A range of processes that currently depend on fossil fuels but are really hard to electrify will depend on the development of genuinely clean fuels, and for that to happen, much more efficient catalysts wi July 22nd, 2022

Generating power where seawater and river water meet July 22nd, 2022

First electric nanomotor made from DNA material: Synthetic rotary motors at the nanoscale perform mechanical work July 22nd, 2022

At the water’s edge: Self-assembling 2D materials at a liquid–liquid interface: Scientists find a simple way to produce heterolayer coordination nanosheets, expanding the diversity of 2D materials July 22nd, 2022

Chip Technology

The best semiconductor of them all? Researchers have found a material that can perform much better than silicon. The next step is finding practical and economic ways to make it July 22nd, 2022

Buckyballs on gold are less exotic than graphene July 22nd, 2022

Quantum computer works with more than zero and one: Quantum digits unlock more computational power with fewer quantum particles July 22nd, 2022

At the water’s edge: Self-assembling 2D materials at a liquid–liquid interface: Scientists find a simple way to produce heterolayer coordination nanosheets, expanding the diversity of 2D materials July 22nd, 2022

Discoveries

HKU physicists found signatures of highly entangled quantum matter July 22nd, 2022

How different cancer cells respond to drug-delivering nanoparticles: The findings of a large-scale screen could help researchers design nanoparticles that target specific types of cancer July 22nd, 2022

The best semiconductor of them all? Researchers have found a material that can perform much better than silicon. The next step is finding practical and economic ways to make it July 22nd, 2022

Buckyballs on gold are less exotic than graphene July 22nd, 2022

Announcements

Quantum computer works with more than zero and one: Quantum digits unlock more computational power with fewer quantum particles July 22nd, 2022

Biology’s hardest working pigments and ‘MOFs’ might just save the climate: A range of processes that currently depend on fossil fuels but are really hard to electrify will depend on the development of genuinely clean fuels, and for that to happen, much more efficient catalysts wi July 22nd, 2022

Generating power where seawater and river water meet July 22nd, 2022

First electric nanomotor made from DNA material: Synthetic rotary motors at the nanoscale perform mechanical work July 22nd, 2022

Interviews/Book Reviews/Essays/Reports/Podcasts/Journals/White papers/Posters

Buckyballs on gold are less exotic than graphene July 22nd, 2022

Quantum computer works with more than zero and one: Quantum digits unlock more computational power with fewer quantum particles July 22nd, 2022

Biology’s hardest working pigments and ‘MOFs’ might just save the climate: A range of processes that currently depend on fossil fuels but are really hard to electrify will depend on the development of genuinely clean fuels, and for that to happen, much more efficient catalysts wi July 22nd, 2022

Generating power where seawater and river water meet July 22nd, 2022

NanoNews-Digest
The latest news from around the world, FREE




  Premium Products
NanoNews-Custom
Only the news you want to read!
 Learn More
NanoStrategies
Full-service, expert consulting
 Learn More











ASP
Nanotechnology Now Featured Books




NNN

The Hunger Project