A5055577249- Graphene research and applications
- Thermal properties of materials
- Advanced Thermoelectric Materials and Devices
- 2D Materials and Applications
- MXene and MAX Phase Materials
- Carbon Nanotubes in Composites
- Gas Sensing Nanomaterials and Sensors
- Perovskite Materials and Applications
- Electrocatalysts for Energy Conversion
- Advanced Sensor and Energy Harvesting Materials
- Force Microscopy Techniques and Applications
- Advancements in Battery Materials
- Conducting polymers and applications
- Surface and Thin Film Phenomena
- Advanced Battery Materials and Technologies
- Advanced MEMS and NEMS Technologies
- Thermal Radiation and Cooling Technologies
- Chalcogenide Semiconductor Thin Films
- nanoparticles nucleation surface interactions
- Transition Metal Oxide Nanomaterials
- Advanced Chemical Sensor Technologies
- Supercapacitor Materials and Fabrication
- Advanced Photocatalysis Techniques
- Machine Learning in Materials Science
- Advanced Sensor Technologies Research
Northwestern University
2018-2021
University of Illinois Chicago
2013-2019
Conversion of carbon dioxide (CO2) into fuels is an attractive solution to many energy and environmental challenges. However, the chemical inertness CO2 renders electrochemical photochemical conversion processes inefficient. We report a transition metal dichalcogenide nanoarchitecture for catalytic monoxide (CO) in ionic liquid. found that tungsten diselenide nanoflakes show current density 18.95 milliamperes per square centimeter, CO faradaic efficiency 24%, formation turnover frequency...
Recent isolation of black phosphorus atomic layers (known as phosphorene) has revealed its great potential for use an alternative 2D semiconductor in many areas electronics and optoelectronics. Liquid-phase exfoliation is utilized to produce high-quality nanoflakes with thicknesses down a monolayer the form uniform stable dispersions, allowing pace toward practical applications.
Black phosphorus (BP) atomic layers are known to undergo chemical degradation in humid air. Yet more robust configurations such as films, composites, and embedded structures, BP can potentially be utilized a large number of practical applications. In this study, we explored the sensing characteristics films observed an ultrasensitive selective response toward air with trace-level detection capability very minor drift over time. Our experiments show that drain current sensor increases by ∼4...
Lithium–oxygen (Li–O2) batteries have been recognized as an emerging technology for energy storage systems owing to their high theoretical specific energy. One challenge is find electrolyte/cathode system that efficient, stable, and cost-effective. We present such a based on molybdenum disulfide (MoS2) nanoflakes combined with ionic liquid (IL) work together effective cocatalyst discharge charge in Li–O2 battery. Cyclic voltammetry results show superior catalytic performance this both oxygen...
A fundamental understanding of chemical sensing mechanisms in graphene-based field-effect transistors (chemFETs) is essential for the development next generation sensors. Here we explore hidden modalities responsible tailoring gas detection ability pristine graphene sensors by exposing chemFETs to electron donor and acceptor trace vapors. We uncover that sensitivity (in terms modulation electrical conductivity) not necessarily intrinsic graphene, but rather it facilitated external defects...
Electrochemistry is central to applications in the field of energy storage and generation. However, it has advanced far more slowly over last two decades, mainly because a lack suitable affordable catalysts. Here, we report synthesis highly crystalline layered three-dimensional (3D) molybdenum disulfide (MoS2) catalysts with bare Mo-edge atoms demonstrate their remarkable performance for hydrogen evolution reaction (HER). We found that Mo-edge-terminated 3D MoS2 directly grown on graphene...
Graphene has served as the model 2D system for over a decade, and effects of grain boundaries (GBs) on its electrical mechanical properties are very well investigated. However, no direct measurement correlation between thermal transport graphene GBs been reported. Here, we report simultaneous comparison in supported single crystalline to across an individual GB. Our experiments show that conductance (per unit area) through isolated GB can be up order magnitude lower than theoretically...
Despite many theoretical predictions indicating exceptionally low energy barriers of ionic transport in phosphorene, the pathways this two-dimensional (2D) material has not been experimentally demonstrated. Here, using situ aberration-corrected transmission electron microscopy (TEM) and density functional theory, we studied sodium ion phosphorene. Our high-resolution TEM imaging complemented by loss spectroscopy demonstrates a precise description anisotropic ions migration along [100]...
Two-dimensional materials, including graphene, transition metal dichalcogenides and their heterostructures, exhibit great potential for a variety of applications, such as transistors, spintronics, photovoltaics. While the miniaturization offers remarkable improvements in electrical performance, heat dissipation thermal mismatch can be problem designing electronic devices based on two-dimensional materials. Quantifying expansion coefficient 2D materials requires temperature measurements at...
In many device architectures based on 2D materials, a major part of the heat generated in hot‐spots dissipates through‐plane direction where interfacial thermal resistances can significantly restrain removal capability device. Despite its importance, there is an enormous (1–2 orders magnitude) disagreement literature transport characteristics MoS 2 and other transition metal dichalcogenides (TMDs) (0.1–14 MW m −2 K −1 ). this report, boundary conductance (TBC) across graphene monolayers with...
Two-dimensional (2D) hybrid organic-inorganic perovskites (HOIPs) are recent members of the 2D materials family with wide tunability, highly dynamic structural features, and excellent physical properties. Ultrathin HOIPs their heterostructures other have been exploited for study phenomena device applications. The in-plane mechanical properties ultrathin critical understanding coupling between fields integrated devices Here we report freestanding lead iodide perovskite membranes dependence on...
Reliable fabrication of lateral interfaces between conducting and semiconducting 2D materials is considered a major technological advancement for the next generation highly packed all-2D electronic circuitry. This study employs seed-free consecutive chemical vapor deposition processes to synthesize high-quality MoS2 -graphene heterostructures comprehensively investigated their properties through combination various experimental techniques theoretical modeling. These results show that devices...
Wrinkle structures are commonly seen on graphene grown by the chemical vapor deposition (CVD) method due to different thermal expansion coefficient between and its substrate. Despite intensive investigations focusing electrical properties, nanotribological properties of wrinkles influence wrinkle wrinkle-free remain less understood. Here, we report observation anisotropic nanoscale frictional characteristics depending orientation in CVD-grown graphene. Using friction force microscopy, found...
Van der Waals interactions in 2D materials have enabled the realization of nanoelectronics with high-density vertical integration. Yet, poor energy transport through such 2D-2D and 2D-3D interfaces can limit a device's performance due to overheating. One long-standing question field is how different encapsulating layers (e.g., contact metals or gate oxides) contribute thermal at interface their 3D substrates. Here, novel self-heating/self-sensing electrical thermometry platform developed...
Line defects, including grain boundaries and wrinkles, are commonly seen in graphene grown by chemical vapor deposition. These one-dimensional defects believed to alter the electrical mechanical properties of graphene. Unfortunately, it is very tedious directly distinguish from wrinkles due their similar morphologies. In this report, high-resolution Kelvin potential force microscopy (KPFM) employed measure work function distribution line defects. The characteristic variations boundaries,...
Abstract The optimization of traditional electrocatalysts has reached a point where progress is impeded by fundamental physical factors including inherent scaling relations among thermokinetic characteristics different elementary reaction steps, non‐Nernstian behavior, and electronic structure the catalyst. This indicates that currently utilized classes may not be adequate for future needs. study reports on synthesis characterization new class materials based 2D transition metal...
Many strategies have been employed to maintain an "optimal carrier concentration" achieve a high thermoelectric power factor in n-type PbTe. Here, we show that can also be achieved over broad temperature range without attaining the optimal concentration by alloying PbTe with GaSb. We find GaSb dissociates into Ga and Sb dissolves matrix. atoms introduce impurity levels above valence band of giving rise diminished electron–phonon coupling increased effective mass leading Seebeck coefficient...
The ongoing shrinkage in the size of two-dimensional (2D) electronic circuitry results high power densities during device operation, which could cause a significant temperature rise within 2D channels. One challenge Raman thermometry materials is that commonly used high-frequency modes do not precisely represent some because peak broadening and intensity weakening at elevated temperatures. In this work, we show low-frequency E2g2 shear mode can be to accurately extract measure thermal...
Structural defects and heterogeneities play an enormous role in the formation of localized hot spots 2D materials used a wide range applications from electronics to energy systems. In this report, we employ scanning thermal microscopy (SThM) spatially map temperature rise across various titanium carbide (Ti3C2T x; T stands for surface terminations) MXene nanostructures under high electrical bias with sub-50 mK resolution sub-100 nm spatial resolution. We investigated several Ti3C2T x flakes...
Abstract Heat transport across vertical interfaces of heterogeneous 2D materials is usually governed by the weak Van der Waals interactions surface‐terminating atoms. Such play a significant role in thermal transition metal carbide and nitride (MXene) atomic layers due to their hydrophilic nature variations surface terminations. Here, metallicity atomically thin Ti 3 C 2 T z MXene, which also verified scanning tunneling spectroscopy for first time, exploited develop self‐heating/self‐sensing...
Through-plane thermal transport accounts for a major fraction of heat dissipation from hot-spots in many existing devices made two-dimensional (2D) materials. In this report, we performed set electrical thermometry measurements and 3D finite element analyses to quantify the limits power monolayer graphene, representative 2D materials, fabricated on various technologically viable substrates such as chemical vapor deposited (CVD) diamond, tape-casted (sintered) aluminum nitride (AlN), single...
Abstract Lateral heterogeneities in atomically thin 2D materials such as in‐plane heterojunctions and grain boundaries (GBs) provide an extrinsic knob for manipulating the properties of nano‐ optoelectronic devices harvesting novel functionalities. However, these have potential to adversely affect performance reliability through formation nanoscopic hot‐spots. In this report, scanning thermal microscopy (SThM) is utilized map spatial distribution temperature rise within monolayer transition...
A 20nm thick Ni resistor element was fabricated on a 1μm thick, 400μm wide silicon nitride bridge via bulk micromachining. By applying given power to the its temperature increases, as pressure decreases, since fewer gas particles are available transfer heat away from resistor. Rather than sensing resistance change, thin film thermocouple consisting of and Cr in center element, allowing direct measurement voltage signal. It will be shown that by fabricating two gauges with different d's, but...