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Sheng Dai Named 2022 Clarivite Highly Cited Researcher

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Sheng Dai

Each year, Clarivate identifies the world’s most influential researchers ─ the select few who have been most frequently cited by their peers over the last decade. In 2022, fewer than 7,000, or about 0.1%, of the world’s researchers, in 21 research fields and across multiple fields, have earned this exclusive distinction.Dai is among this elite group recognized for your exceptional research influence, demonstrated by the production of multiple highly-cited papers that rank in the top 1% by citations for field and year in the Web of Science. Dai was also included in the prestigious ranking in 2021 and 2020, making this his third consecutive year on Clarivite’s Highly Cited Researchers list.

Dai Group Published in Nature Communications

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The Dai Group published their latest research “Intra-crystalline mesoporous zeolite encapsulation-derived thermally robust metal nanocatalyst in deep oxidation of light alkanes” in Nature Communications.

Zeolite-confined metal nanoparticles (NPs) have attracted much attention owing to their superior sintering resistance and broad applications for thermal and environmental catalytic reactions. However, the pore size of the conventional zeolites is usually below 2 nm, and reactants are easily blocked to access the active sites.

In this work, a facile in situ mesoporogen-free strategy is developed to design and synthesize palladium (Pd) NPs enveloped in a single-crystalline zeolite (silicalite-1, S-1) with intra-mesopores (termed Pd@IM-S-1). Pd@IM-S-1 exhibited remarkable light alkanes deep oxidation performances, and it should be attributed to the confinement and guarding effect of the zeolite shell and the improvement in mass-transfer efficiency and active metal sites accessibility. The Pd–PdO interfaces as a new active site can provide active oxygen species to the first C-H cleavage of light alkanes. “This work exemplifies a promising strategy to design other high-performance intra-crystalline mesoporous zeolite-confined metal/metal oxide catalysts for high-temperature industrial thermal catalysis”, said Honggen Peng, a previous visiting scholar in the Dai Group.

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Graduate Student Spotlight – Halstenberg

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Phillip Halstenberg is a chemistry graduate student currently conducting research in the Dai Group.

Halstenberg is originally from Kannapolis, North Carolina and attended the University of North Carolina at Wilmington for his BS in chemistry where he began working in the chemistry laboratories under the guidance of Dr. S. Bart Jones and Dr. Robert Hancock.

Sheng Dai, Professor and ORNL-UT Joint Faculty was invited to give a presentation during the UNCW’s guests lecture series. Dai visited the labs and met Halstenberg as their lab was collaborating with Dai on complexometric titrations related to the Uranium from Seawater Project. “We spoke about my efforts toward the research objectives and my plans for medical school and my intention to work for a year or so prior to applying,” Halstenberg said. “He told me that if I was interested, I could continue my work toward the Uranium from Seawater Project at Oak Ridge National Laboratory during my gap year. I quickly expressed interest in the opportunity and subsequently began work as an intern via the Higher Education Research Experience program offered by Oak Ridge Associated Universities.”

“A few years later I was still working at ORNL now a Post Bachelor Research Associate long since deciding my calling was not toward medical, but chemical sciences,” Halstenberg said. “I soon realized that in competitive research environments, such as a national laboratory, a PhD can be a requirement for certain advancement opportunities.

Halstenberg had been working on projects related to the most recently developed, generation IV, nuclear reactors for about a year when he decided to apply to chemistry PhD programs. “I feel strongly that technology related to the latest molten salt reactors will have a substantial societal impact if developed and implemented correctly,” Halstenberg said “My goal was to enter a graduate program where I could work toward furthering our understanding of these systems from a fundamental chemistry perspective.”

Sheng Dai had joined the efforts of recently established Energy Frontier Research Center: Molten Salts in Extreme Environments and the Nuclear Energy University Program. “We spoke about my efforts toward molten salt, and I decided to attend UTK and complete my PhD working for these programs,” Halstenberg said. “It helped my decision when I realized that UTK was home to Gleb Mamantov, who made many of the first breakthroughs in molten salt research ~60 years ago. ORNL has also always been on the cutting edge of these molten salt reactors.”

Halstenberg’s research focus is molten chloride salts. Over the last three years, he has built a world class experimental salt chemistry facility in Buehler Hall on UTK’s main campus. These labs support research efforts related to molten chloride salts  worldwide. All the experiments are related to understanding the fundamental chemical interaction in molten chloride systems. The facility provides the salt matrices required across all of the collaborating institutions and assist in the development of their experimental methodology.

“In addition to providing the salt mixtures, the focus of my molten salt work in the UTK laboratory is the quantifying impurities, spectroscopic speciation studies, characterization of thermophysical properties, characterization of colloidal mixture properties, development of ultra-high temperature magnets, bulk metallic glass formation and analysis, containment corrosion studies, and novel synthetic pathways,” Halstenberg said.

“I enjoy the diversity of research being conducted within the Dai group,” Halstenberg said.  “This coupled with the encouragement of a collaborative group effort results in an environment that is very conducive to research progress.”

“Much of my work prior to graduate school was covered under various confidentiality agreements that prohibited its open publishing,” Halstenberg said. “Although, I have coauthored 16 peer reviewed journal articles since entering graduate school in 2018.”

“Upon graduation, I will continue working with national laboratories on research toward advancing the fundamental chemical understanding of these molten chloride systems. After proper technological maturation, I intend to move from research to development,” Halstenberg said. “I will take the knowledge I have gained synthesizing and purifying these materials on a laboratory scale and use it to build the supply chains needed to provide materials for industrial scale production of molten salt reactors.”

Dai Group Published in Nature Communications

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The Dai Group published their collaborative research “Formation of three-dimensional bicontinuous structures via molten salt dealloying studied in real-time by in situ synchrotron X-ray nano-tomography” in Nature Communications.

Three-dimensional bicontinuous porous materials formed by dealloying contribute significantly to various applications including catalysis, sensor development and energy storage. This work studies a method of molten salt dealloying via real-time in situ synchrotron three-dimensional X-ray nano-tomography.

Quantification of morphological parameters determined that long-range diffusion is the rate-determining step for the dealloying process. The subsequent coarsening rate was primarily surface diffusion controlled, with Rayleigh instability leading to ligament pinch-off and creating isolated bubbles in ligaments, while bulk diffusion leads to a slight densification. Chemical environments characterized by X-ray absorption near edge structure spectroscopic imaging show that molten salt dealloying prevents surface oxidation of the metal.

“In this work, gaining a fundamental mechanistic understanding of the molten salt dealloying process in forming porous structures provides a nontoxic, tunable dealloying technique and has important implications for molten salt corrosion processes, which is one of the major challenges in molten salt reactors and concentrated solar power plants,” said Phillip Halstenberg, graduate student in the Dai Group.

Dai Group Published in Nano Energy and Chem. Commun.

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The Dai Group published their work “Room temperature synthesis of high-entropy Prussian blue analogues” in Nano Energy.

High-entropy Prussian blue analogues (HEPBAs) integrating the highly dispersed active sites of high-entropy materials with intrinsic 3D diffusion channels and the redox-active sites of Prussian blue analogues have great potential in electrochemical applications but have not been realized. In this work, a series of HEPBAs were successfully synthesized under room temperature combining mechanochemistry with wet chemistry for the first time.

High-entropy Prussian blue analogues (HEPBAs) were fabricated by combining mechanochemistry with wet chemistry. As an optimal element combination, high-entropy K(MgMnFeNiCu)Fe(CN)6 exhibited enhanced higher capacitances than all the single-component PBAs.

The group also published their work “Overcoming the phase separation within high-entropy metal carbide by poly(ionic liquid)s†” in Chemical Communications. 

High-entropy crystalline materials are attracting more attention. In principle, high-entropy metal carbides (HMCs) that contain five or more metal ions, possess more negative free energy value during catalysis. But its preparation is challenging because of the immiscibility of multi metal cations in a single carbide solid solution.

Here, a rational strategy for preparing HMC is proposed via a coordination-assisted crystallization process in the presence of Br-based poly(ionic liquids). Through this method, Mo0.2W0.2V0.2Cr0.2Nb0.2C nanoparticles, with a single cubic phase structure, incorporated on porous carbon, are obtained (HMC@NC). By combination of well dispersed small particle size (∼4 nm), high surface area (∼270 m2 g−1), and high-entropy phase, HMC@NC can function as a promising catalyst for the dehydrogenation of ethylbenzene. Unexpected activity (EB conv.: 73%) and thermal stability (>100 h on steam) at 450 °C are observed. Such a facile synthetic strategy may inspire the fabrication of other types of HMCs for more specific tasks.

Dai Group Published in ACS Energy Letters

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The Dai group published their research “Surpassing the Organic Cathode Performance for Lithium-Ion Batteries with Robust Fluorinated Covalent Quinazoline Networks” in  ACS Energy Letters.

Organic electrode materials have promising application prospects in energy storage, but issues including rapid capacity fading and poor power capacity restrict their practical applications. Herein, nanoporous fluorinated covalent quinazoline networks (F-CQNs) were constructed by condensation of fluorinated aromatic aminonitrile precursors via an ionothermal pathway.

Precise control of the reaction parameters afforded F-CQN-1-600 material featuring high surface area, permanent porosity, high nitrogen content (23.49 wt %), extended π-conjugated architecture, layered structure, and bipolar combination of benzene and tricycloquinazoline. Synergy among these unique properties leads to a good performance as a cathode source for lithium-ion batteries (LIBs) in terms of high capacity (250 mA h g–1 at 0.1 A g–1), high rate capability (105 mA h g–1 at 5.0 A g–1), and impressive cycling stability (95.8% retention rate after 2000 cycles at 2.0 A g–1 together with a high Coulombic efficiency of 99.95%), surpassing most of the previous organic cathode counterparts

Dai Published in Chem

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In a collaborative piece, UT Chemistry’s Sheng Dai and Pasquale Fulvio from Texas A&M’s Department of Nuclear Engineering published their work “Porous Liquids: The Next Frontier” in Chem.

Porous liquids are a new class of molecular- and colloidal-size porous materials that combine permanent porosity of solid sorbents and fluid properties of liquids. Different from transient molecular clathrates, porous liquids have the potential to reinvent materials syntheses and unify homogeneous and heterogeneous separations and catalytic and energy-related processes, previously ascribed to liquids and porous solids, respectively.

Surface areas and pore volumes of the first examples of porous liquids based on porous molecular organic cages restricted their potential for technological applications. Recent advances in ionic liquid-based colloidal suspensions or covalently stabilized nanocomposites have improved the adsorption properties and increased our ability to tailor chemical composition and pore architecture. These hybrid porous liquids, however, still present challenges such as high melting temperatures, density, and viscosity.

This critical review discusses these challenges and presents opportunities for selected emerging applications based on analogous structure to that of traditional colloidal systems.

Dai 2020 Highly Cited Researcher

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Each year, Clarivate™ identifies the world’s most influential researchers ─ the select few who have been most frequently cited by their peers over the last decade. In 2020, fewer than 6,200, or about 0.1%, of the world’s researchers, in 21 research fields and across multiple fields, have earned this exclusive distinction.
Sheng Dai Sheng Dai is among this elite group recognized for exceptional research influence, demonstrated by the production of multiple highly-cited papers that rank in the top 1% by citations for field and year in the Web of Science™.

Dai Group Published in Advanced Energy & Sustainability Research

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The Dai Group published their work “Organic Cathode Materials for Lithium‐Ion Batteries: Past, Present, and Future” in Advanced Energy & Sustainability Research.

With the rapid development of energy storage systems in power supplies and electrical vehicles, the search for sustainable cathode materials to enhance the energy density of lithium‐ion batteries (LIBs) has become the focus in both academic and industrial studies. Currently, the widely utilized inorganic cathode materials have suffered from drawbacks such as limited capacity, high energy consumption in production, potential safety hazards, and high‐cost raw materials. It is necessary to develop green and sustainable cathode materials with higher specific capacity, better safety property, and more abundant natural resources.

As alternatives, organic cathode materials possess the advantages of high theoretical capacity, environmental friendliness, flexible structure design, systemic safety, and natural abundance, making them a promising class of energy storage materials.

This research reviews the development history of the organic cathode materials and recent research developments, introducing several categories of typical organic compounds as cathode materials for LIBs, including conductive polymers, organosulfur compounds, organic radical compounds, organic carbonyl compounds, and organic imine compounds. The electrochemical performance, electrode reaction mechanism, and pros and cons of different organic cathode materials have been comparatively analyzed to identify their challenges to be addressed.

The future research and improvement directions of the organic cathode materials have also been proposed in this review.

Dai Group Published in I&EC

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The Dai Group published their work “Mechanochemical Synthesis of High-Purity Anhydrous Binary Alkali and Alkaline Earth Chloride Mixtures” in the Journal of Industrial and Engineering Chemistry (I&EC).

A direct synthesis route for high-purity, anhydrous binary salt mixtures has been developed. This atom efficient, solvent-free process is easily scalable, with the potential to produce salt mixtures that meet the purity standards required for industrial heat transfer and nuclear applications. The essence of the methodology lies in mechanochemical synthesis of carnallite precursors that can mitigate the hydrolysis of MgCl2·6H2O under direct heating. Each dehydrated salt carnallite was then analyzed for purity and oxide content through subsequent powder X-ray diffraction, and strong acid titration. This process presents a more effective alternative route compared to previous methods for obtaining low-oxide, high-purity chloride salt mixtures.

Phillip Halstenberg, graduate student, oversaw all experimentation and writing of this manuscript. Dmitry Maltsev was responsible for pXRD
measurements and data evaluation. Ellie Kim and Dianna
Nguyen performed titrations and calculations to quantify oxide
content as part of their undergraduate research. Sheng
Dai advised and oversaw all experimentation.