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HIGH-ENTROPY-ALLOY NANOPARTICLES SYNTHESIS    

The controllable incorporation of multiple immiscible elements into a single nanoparticle merits untold scientific and technological potential, yet remains a challenge using conventional synthetic techniques. Our group invented a general route for alloying up to eight dissimilar elements into single-phase solid-solution nanoparticles, referred to as high-entropy-alloy nanoparticles (HEA-NPs) by the carbothermal shock (CTS). We synthesized a wide range of multicomponent nanoparticles with a desired chemistry (composition), size, and phase (solid solution, phase-separated) by controlling parameters (substrate, temperature, shock duration, and heating/cooling rate) of CTS.

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For more information, please visit: https://www.highentropy.info/

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Recent Papers:​

  • Yao, Y.; Huang, Z.; Xie, P.; Lacey, S.; Jacob, R.; Xie, H.; Chen, F.; Nie, A.; Pu, T.; Rehwoldt, M.; Yu, D.; Zachariah, M.; Wang, C.; Shahbazian-Yassar R.; Li, J.; Hu, L.* Carbo-Thermal Shock Synthesis of High Entropy Alloy Nanoparticles. Science, 2018, 359, 1489 (Article, COVER).

EXTREME MATERIALS AND MANUFACTURING

Extremely high temperature materials and devices are of interest in both research and applications but seldom studied, as most materials melt or decompose at temperatures ranging from 1000 K-3000 K. We invented a simple and facile method via Joule heating of carbon-based nanomaterials to achieve temperatures up to 3000-3300 K which can be used to fabricate extreme materials.  More recently, we demonstrated thermoelectric conversion up to 3000 K via high-temperature-reduced RGO (HT-RGO). The HT-RGO film exhibits dramatically increased thermoelectric performance (54.5 µW/cm·K2), high conductivity (~4000 S/cm), and a high broadband radiation absorption at 3000 K. The flexible HT-RGO can act as an all-in-one thermoelectric prototype that efficiently absorbs thermal radiation energy over a wide temperature range.

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Recent Papers:

  • Bao, W.; Pickel, A. D.; Zhang, Q.; Chen, Y.; Yao, Y.; Wan, J.; Fu, K.; Wang, Y.; Dai, J.; Zhu, H.; Drew, D.; Fuhrer, M.; Dames, C.*; Hu, L.* Flexible, High Temperature, Planar Lighting with Large Scale Printable Nanocarbon Paper. Adv. Mater. 2016, 28, 4684–4691.

  • Li, T.; Pickel, A. D.; Yao, Y.; Chen, Y.; Zeng, Y.; Lacey, S. D.; Yang, B.; Hu, L.* (2018). Thermoelectric properties and performance of flexible reduced graphene oxide films up to 3,000 K. Nature Energy, 3(2), 148.

SOLUTION PROCESSED INKS AND FILMS OF 2D MATERIALS

(Boron Nitride, Graphene/Graphite and MoS2)  

We are interested in solution-based exfoliation of 2D materials into inks that can be printed into different nanostructures for a range of emerging applications. Materials of interest include boron nitride (insulator), graphite/graphene (semi-metal or metal) and MoS2 (semiconductors). For example, our group demonstrated 3D printing of macrofibers made of aligned BN nanosheets that have excellent mechanical strength and high thermal conductivity. Our group also applied the BN paper as a safe battery separator in Li metal batteries.

Recent Papers:

  • Gao, T.; Yang, Z.; Chen, C.; Li, Y.; Fu, K.; Dai, J.; Hitz, E. M.; Xie, H.; Liu, B.; Song, J.; Yang, B.; Hu, L.* Three-Dimensional Printed Thermal Regulation Textiles. ACS Nano 2017, 11 (11), 11513–11520.

  • Zhu, H.; Li, Y.; Fang, Z.; Xu, J.; Cao, F.; Wan, J.; Preston, C.; Bao, Y.; Hu, L.* Highly Thermally Conductive Papers with Percolative Layered Boron Nitride Nanosheets, ACS Nano, 2014, 8, 3606.

MANUFACTURING OF NANOCELLULOSE-BASED

FUNCTIONAL STRUCTURES AND SYSTEMS   

We are exploring the manufacturing of nanocellulose-based functional structures and systems including flexible electronics and solar steam generation devices. By using roll-to-roll or other manufacturing techniques, we demonstrated transparent paper with a high optical transmittance (>85%) and high transmittance haze (>90%) in a broadband wavelength range, which can be extremely attractive for a range of applications in optoelectronics.

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We also demonstrated a cost effective, scalable, yet highly efficient steam-generation device in the form of a bilayer “artificial tree” with a reverse-tree design.

Recent Papers:

  • Yao, Y.; Tao, J.; Zou, J.; Zhang, B.; Li, T.; Dai, J.; Zhu, M.; Wang, S.; Fu, K. K.; Henderson, D; Hu, L.* Light management in plastic–paper hybrid substrate towards high-performance optoelectronics. Energy & Environmental Science 2016, 9, 2278-2285.

  • Liu, H.; Chen, C.; Chen, G.; Kuang, Y.; Zhao, X.; Song, J.; Jia, C.; Xu, X.; Hitz, E.; Xie, H.; Wang, S.; Jiang, F.; Li, T.; Li, Y.; Gong, A.; Yang, R.; Das, S.; Hu, L.* High-Performance Solar Steam Device with Layered Channels: Artificial Tree with a Reversed Design. Adv. Energy Mater., 2017, accepted.

ROLL-TO-ROLL PRINTED TRANSPARENT AND CONDUCTIVE

CARBON NANOTUBE FILMS

Our group has the capability for roll-to-roll fabrication of highly transparent and conductive carbon nanotube films that can be used to replace brittle ITO films for flexible optoelectronics. Prof. Hu has 3 years of industry experience in roll-to-roll printing, patterning, and display integration of such solution-processed films. Prof. Hu and Unidym Inc were featured by New York Times in 2008.

Recent Papers:

  • Hu, L.; Hecht, D. S.; Gruner, G.*; Hu, L.* Carbon Nanotube Thin Films: Fabrication, Properties, and Applications, Chemical Reviews, 2010, 110, 5790.  

  • Hu, L.; Park, Y.; Hecht, D.; Gruner, G.*; Hu, L.* Scalable Carbon Nanotube Thin Films: Fabrication, Properties and Device Applications, MRS Proceeding, 2009, 1109- B10-07.

ION INTERCALATION FOR 2D MATERIAL ENGINEERING

Battery operations with Li ions (or other cations) are always accompanied by electron doping, which can be used alternatively as a novel method for modifying the electrical, optical, mechanical, mechanical and catalytic properties of a material otherwise unattainable using other means of doping (due to its ability to achieve the highest doping level).

 

As a proof of concept, we electrochemically intercalated alkali metal ions (Li ions, Na ions and K ions) in graphitic materials (such as graphene and reduced graphene oxide), which simultaneously increased the transparency and conductivity of these materials with performance values unsurpassed by literature (i.e. 92% transparency and 3.0 ohms/squre). The increase in transparency covers a broad spectrum from the visible to mid-infrared, which can potentially be applied to touch screens, IR imaging and sensing applications.

Recent Papers:

  • Bao, W.; Wan, J.; Han, X.; Cai, X.; Zhu, H.; Kim, D.; Ma, D.; Munday, J.; Drew, D.; Fuhrer, M.*; Hu, L.* Approaching the Limits of Transparency and Conductivity in Graphitic Materials through Lithium Intercalation, Nature Communications, 2014, 5, 4224 

  • Wan, J.; Xu, Y. ; Xu, L.; Yang, Z.; Ozdemir, B.; Wang, Y.; Dai, J.; Lu, A.; Barone, V. *; Hu, L.* Tunable Broadband Nanocarbon Transparent Conductor by Electrochemical Intercalation, ACS Nano, 2017, 11, 788-796. 

  • Wan, J.; Lacey, S.; Dai, J.; Bao, W.; Fuhrer, M.*; Hu, L.* Tuning Two-Dimensional Nanomaterials by Intercalation: Materials, Properties and Applications, Chemical Society Review, 2016, 45, 6742-6765 

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