VTIREF has an active research program on Graphene and Graphene derivatives for exploiting their unique thermal, mechanical and electrical properties for a broad market segment, ranging from transportation through consumer products to electronic industry. Our newly-established Graphene Laboratory at VTIREF has the capability of the synthesis and characterization of Graphene oxide and reduced Graphene oxide and a user-friendly process for the coating of Graphene and Graphene oxide on various substrates. Our future plans are centered on the following projects
Multifunctional and 2-D Materials This thrust aims at investigating the science and engineering of multifunctional and non-traditional 2-D materials and exploiting their unique thermal, mechanical and electrical properties for a broad market segment ranging from transportation through consumer products to the electronic industry. We will develop a process for growing Graphene foams directly onto the back of a silicon wafer which would hold phase-change materials. This novel approach is expected to provide several orders of magnitude improvement in thermal management of electronics systems. A companion project will involve developing Graphene based thermal greases for reduced thermal interface resistance. Graphene is known to be hydrophobic and can serve as an excellent material for promoting drop-wise condensation which has orders of magnitude better heat transfer than film-wise condensation. Graphene oxide, on the other hand, is hydrophilic. A comprehensive understanding of the condensation heat transfer from surfaces modified by patterned coatings of Graphene and Graphene oxide should pave the way for the design of superior thermal performance heat exchangers. Another potential application is the generation of multi-layered super-hydrophobic surfaces for robust water repellency and reduced drag. In parallel, we will study pool boiling heat transfer from Graphene and Graphene oxide-coated surfaces in Fluorinert fluids to ascertain whether these coatings can serve to enhance the critical heat flux, and reduce the hysteresis effect commonly associated with such fluids. The results will have strong implications for electronic cooling applications. This research program focuses on exploring the interface between Physics and Material Science to innovate in the critical field of advanced multi-functional materials. Our current research on ferroelectrics, piezoelectrics and multiferroics is driven by many long-term technological aspirations with state-of-the-art sensors, nonvolatile memories, spintronic devices, to name a few. A major slice of our effort emphasizes exploring the fundamental science of these materials to gain deeper understanding about structure – property relationships, which consequtively can bring about a significant shift in the research and applications of these materials. To be precise, this research broadly strives to establish the corelation between crystallography, crystallographic anisotropy, domains and domain-dynamics on electro-mechanical behavior of ferroelectrics, piezoelectrics and multiferroics. Electron paramagnetic resonance (EPR) and other characterization techniques are used to investigate the presence of ionic defects, their mutual interaction and subsequent consequences on the functional behavior of these materials. Another facet of our research focuses on gradual advancement of the functional behavior of few technologically vital multi-functional materials to advance their feasability for device applications. We utilize scientific methods and processing techniques to engineer some of the key functional properties of materials such as sodium potassium niobate, bismuth ferrite and other lead-based perovskites. We intend to utilize some of these materials with improved functional behavior for device applications. Considering the exciting prospects for multifunctional oxides at nanoscale, some of this effort will be devoted to the synthesis of size- controlled nanoparticles and their characterization for variety of applications. Global Ambassador of Institute for
Research
Science and Engineering
At the core of this research program is Virginia Tech’s novel process to convert coal to graphene. With its superior properties—Young’s modulus, high thermal conductivity, high electron mobility, strong chemical resistance, and large specific surface area—, graphene has been hailed as the transformative new material driving economic growth. However, the current method of choice for its synthesis (modified Hummer’s method) is prohibitively expensive and chemicals-intensive. As a result, the full potential of graphene has not been exploited. In addition, since graphite is mostly imported from China, it has been designated as a critical material that needs replacement with local materials. A process that would produce graphene from coal economically and with minimal environmental cost would thus not only provide an important pathway to realize the full economic value of coal resources but also replace graphite as a precursor material. Motivated by this, Professor Mahajan and Dr. Lee (members of our Virginia Tech (VT) team) have recently developed a novel one-pot facile process (PCT/US19/66941, December 17, 2019) to convert coal to graphene oxide and graphene (multilayer graphene, with as few as three layers). A flow diagram of the modified Hummer’s method and VT-process is shown in Fig. xx.We note that to date, the one-pot process has been demonstrated at the laboratory scale for semi-anthracite coal (81.1 wt.% of fixed carbon, 13.2 wt.% of ash, 3.4 wt.% of volatile matter, and 2.3 wt.% of moisture content). At VT India, we have focused on developing/manipulating the VT’s novel process to different ranks of coals available in India. We have characterized the graphene oxide (coal-GO) and Coal-multilayer graphene (coal-MLG) for their surface, structural and morphological properties for a comparison with those for graphite-GO and graphite-MLG. For expansive use of the regional coal resources, we will identify other high by- and derived-products of our carbon nanomaterials (coal-GO and coal-MLG, quantum dots, composites and coatings) for a diverse set of applications. These include additives for lightweight composites for automobiles and tires, LED lighting fixture, electromagnetic interference (EMI) shielding and thermal interface materials (TIM) for high power computing systems, cement composites, more efficient electrodes for energy storage or conversion, and biomedical sensors. We plan to work on the development of the new coal economy. To this end, we will identify the target market entry and follow-up products for our carbon nanomaterials, on the basis of which we will develop, test and characterize our coal-derived products. A key deliverable would be the scaling up of laboratory processes for commercial production. In this, we would closely work with the industry. When completed, the work will lay the foundation of a graphene economy in India.
Advanced Multifunctional Materials
Dr. Roop Mahajan
Critical Technology and Applied Science