Ph.D., Chemistry and Chemical Engineering
M.E., Materials Science & Engineering
B.E., Polymer Science and Engineering
ABC Channel 8 News tv
RICHMOND, Va. (WRIC)– A team of researchers at Virginia Commonwealth University are working to develop a face mask that not only prevents the spread of COVID-19 but actually kills the virus. The research team said that typically, the masks we’re used to wearing can capture airborne viruses, but they do not kill the virus. The researchers are using a chemical similar to what is found in a disinfectant wipe, but have turned it into a solid. The chemical is turned into polymer fiber and coated on the outer layer of the fabric surface. “This bacteria or virus can still live on the surface of your face mask for hours or even days,” VCU College of Engineering Professor, Dr. Wei-Ning Wang said. Wang said this can be dangerous and can cause cross-contamination.view more
Virginia Commonwealth University online
VCU researchers are developing a material designed to capture — and kill — microbes, including the COVID-19 viruses. Highly contagious new COVID-19 strains call for better masks. Wei-Ning Wang, Ph.D., is working to meet this need with a mask design that uses chemical reactions and electrical charges to kill microbes, including the coronavirus particle. “The problem with almost all commercially available masks is that they are passive devices. They capture airborne pathogens, but they don’t kill them,” said Wang, an associate professor in the Department of Mechanical and Nuclear Engineering in the Virginia Commonwealth University College of Engineering. Screening out microbes can be an effective strategy, he added. “But in high-risk areas like hospitals, you have a lot of airborne bacteria or virus collected on the mask’s surface, so there is an elevated risk of contamination, especially while removing or changing masks.”view more
USA Today online
... Dr. Wei-Ning Wang, associate professor of mechanical and nuclear engineering at the Virginia Commonwealth University College of Engineering, explains, “Since almost all particulate matters, including airborne pathogens, carry charges (mostly negative charges), this technique uses electrostatic interactions to attract the particles and/or use high electric current to kill the pathogens.” ...view more
VCU Engineering News online
Several VCU College of Engineering researchers were selected to receive the first round of awards from the VCU COVID-19 Rapid Research Funding Opportunity. Wang is developing an antiviral face mask that captures and kills pathogens, including the new coronavirus, on the mask's surface. It is reusable and composed of novel materials that are non-toxic and low cost. This new face mask design is an improvement over commercial masks, which are unable to kill airborne pathogens. Ping Xu, Ph.D., a professor in VCU’s schools of Dentistry and Medicine, is conducting airborne virus analysis for this project.view more
VCU Engineering News online
Technologies for 3D-printed orthopedic implants that promote bone formation and filters that produce their own bacteria-killing agents received 2019 Commonwealth Research Commercialization Fund (CRCF) awards. Both research efforts are led by investigators from the VCU College of Engineering. The CRCF accelerates economic growth in Virginia by supporting innovative technology research, development and commercialization that addresses important state, regional and national problems.view more
VCU Engineering News online
Xiang He, a doctoral candidate in VCU’s Department of Mechanical and Nuclear Engineering, has been selected to receive a prestigious Chinese Government Award for Outstanding Self-Financed Students Abroad. He’s research focuses on the rational design of metal-organic, framework-based nanomaterials for environmental and energy sustainability. His adviser is Weining Wang, Ph.D., assistant professor of mechanical engineering.view more
Dr. Wang’s research covers a wide range of topics in Aerosol Science & Technology as well as Environmental Science & Engineering, with a major focus on aerosol process development and measurement, materials synthesis and characterization, and heterogeneous catalysis, aiming to solve the fundamental issues, such as nucleation, crystal growth, and self-assembly, as well as transport phenomena (particle, charge, heat, and mass transfers) , towards addressing critical challenges in the sectors of environment and human health.
Commonwealth Research Commercialization Fund (CRCF)
Heating, ventilation, and air conditioning (HVAC) systems are one of the most common and effective methods to improve indoor air quality (IAQ) by using ventilation and filtration, which helps to reduce the risks of Sick Building Syndrome and Building Related Illness. However, conventional HVAC air filters can accumulate airborne germs, such as bacteria, viruses, and fungi. Many of these germs are infectious pathogens, which may be released to the filtered air to cause infectious diseases. The major objectives of this project are to further develop the nanowire filters to bring the invention into the HVAC air filter market in a rapid manner.
National Science Foundation
The primary objective of this research is to investigate and develop a microdroplet-based nanomanufacturing process, consisting of a pressure and temperature-controllable aerosol reactor with an integrated online characterization platform, for the fabrication of metal organic frameworks or MOFs. The project addresses the fundamental issues of long synthesis duration, slow crystal nucleation and growth, non-uniform heating, and inhomogeneous mixing that plague conventional wet-chemistry methods. By combining experimental investigations with numerical simulations on transport phenomena at both the macroscopic and microscopic scales, the detailed formation and self-assembly mechanisms of metal organic frameworks-based nanomaterials in microdroplets are unraveled. This research transforms the fabrication of metal organic frameworks-based nanomaterials from bulk solution-based methods to a microdroplet-based approach. The project provides a rapid, continuous and scalable platform for manufacturing such important nanomaterials with controllable nanostructures, and offers new insights into the quantitative understanding of pathways for their formation. The availability of affordable MOFs in large quantities should help tackle a variety of energy and environmental challenges, such as energy sources, air quality control, and water treatment.
American Chemical Society Petroleum Research Fund (ACS-PRF)
The overarching goal of this project is to design and synthesize metal organic framework (MOF)-based nanocomposites with controlled surface functionality to photocatalytically convert carbon dioxide (CO2), generated by combustion of petroleum, coal and natural gas, to useful chemicals, which can be further converted to petroleum products.
VCU Presidential Research Quest Fund (PeRQ)
The project aims to create novel photocatalysts with hierarchical structures and heterogeneous wettability, consisting of discrete, highly porous metal-organic-framework nanocrystals and titanium dioxide nanoarrays, by rapid aerosol processes for efficient CO2 photoreduction. The control of wettability heterogeneity is the key to the enhancements on selective adsorption of CO2 and H2O molecules, and hence the CO2 photoreduction efficiency of the nanocomposites. The proposed work directly responds to the National Academy of Engineering’s Grand Challenges by developing efficient carbon conversion methods. The success of the project will deepen our understanding on the structure-property-performance relationship of the photocatalysts for CO2 photoreduction.
This course is intended to introduce the student to the fundamentals of heat transfer. The three modes of heat transfers, conduction, convection, and radiation, will be introduced. In particular, the conduction and convection heat transfers will be explained in details. Various rate constants and equations will be introduced to solve practical heat transfer problems. Lecture topics will include a review of fundamental concepts in thermodynamics.
This course is intended to introduce the student to the fundamentals of HVAC systems. The typical HAVC systems and understand the basic terminology will be overviewed firstly. The next topic is to understand psychometrics, which deals with the properties of moist air, and the representation of various air conditioning processes on a psychrometric chart. We will then discuss some of the common basic elements of HVAC systems and the types of systems that are used to meet the requirements of different buildings. Since HVAC is used to maintain not only an acceptable level of thermal comfort within a space but also a healthy environment, the conditions that provide a comfortable and healthful indoor environment for humans are introduced. They are addressed by physiological considerations, environmental indices, and, in particular, the control of indoor air quality which causes increasing attention. The design of a basic HVAC system will be also introduced, which is dependent on a good estimate of the heat gain or loss in a space to be conditioned. Basic heating and cooling load calculations will be discussed.
The team will be working to develop novel aerosol processes to synthesize various nanoparticles, perform online and offline characterization, toxicity evaluation, and apply them for different applications, such as air purification, water treatment, and medical imaging and therapy. VCU’s School of Engineering has a strong team focusing on aerosol research, covering synthesis, characterization, transport, toxicity evaluation, and modeling. The projects will be designed and advised by the team to offer both fundamental aerosol knowledge and experimental skills. The team is looking for interested sophomore, junior, and senior undergraduate Mechanical, Chemical, Biomedical and Electrical Engineering students with a strong desire to participate in the process development, simulation, and nanoparticle synthesis and characterization. The students involved in the projects will gain multidisciplinary knowledge in materials science, particle characterization, process development, photocatalysis, transport, and toxicity evaluation techniques, enabling them to choose diverse career paths in the future.view more
Graduate course. To be taught in Spring 2018. More details to come shortly.
ZnO@ZIF-8 core–shell nanofibers were manufactured via direct growth of ZIF-8 on eletrospun ZnO nanofibers for the first time. The versatility of this synthesis strategy for other ZnO@ZIF nanofibers was also demonstrated. The as-synthesized ZnO@ZIF-8 nanofibers exhibit enhanced CO2 adsorption ability and unique adsorption preference as compared to pristine ZnO nanofibers.view more
ACS Applied Materials & Interfaces
A copper-based metal–organic framework (MOF), [Cu3(TMA)2(H2O)3]n (also known as HKUST-1, where TMA stands for trimesic acid), and its TiO2 nanocomposites were directly synthesized in micrometer-sized droplets via a rapid aerosol route for the first time. The effects of synthesis temperature and precursor component ratio on the physicochemical properties of the materials were systematically investigated. Theoretical calculations on the mass and heat transfer within the microdroplets revealed that the fast solvent evaporation and high heat transfer rates are the major driving forces. The fast droplet shrinkage because of evaporation induces the drastic increase in the supersaturation ratio of the precursor, and subsequently promotes the rapid nucleation and crystal growth of the materials. The HKUST-1-based nanomaterials synthesized via the aerosol route demonstrated good crystallinity, large surface area, and great photostability, comparable with those fabricated by wet-chemistry methods. With TiO2 embedded in the HKUST-1 matrix, the surface area of the composite is largely maintained, which enables significant improvement in the CO2 photoreduction efficiency, as compared with pristine TiO2. In situ diffuse reflectance infrared Fourier transform spectroscopy analysis suggests that the performance enhancement was due to the stable and high-capacity reactant adsorption by HKUST-1. The current work shows great promise in the aerosol route’s capability to address the mass and heat transfer issues of MOFs formation at the microscale level, and ability to synthesize a series of MOFs-based nanomaterials in a rapid and scalable manner for energy and environmental applications.view more
Journal of the American Chemical Society
A facile development of highly efficient Pt-TiO2 nanostructured films via versatile gas-phase deposition methods is described. The films have a unique one-dimensional (1D) structure of TiO2 single crystals coated with ultrafine Pt nanoparticles (NPs, 0.5–2 nm) and exhibit extremely high CO2 photoreduction efficiency with selective formation of methane (the maximum CH4 yield of 1361 μmol/g-cat/h). The fast electron-transfer rate in TiO2 single crystals and the efficient electron–hole separation by the Pt NPs were the main reasons attributable for the enhancement, where the size of the Pt NPs and the unique 1D structure of TiO2 single crystals played an important role.view more
D. Wang, Z. Li, J. Zhou, H. Fang, X. He, P. Jena, J.-B. Zeng, and W.-N. Wang
The detection and removal of volatile organic compounds (VOCs) are of great importance to reduce the risk of indoor air quality concerns. This study reports the rational synthesis of a dual-functional Janus nanostructure and its feasibility for simultaneous detection and removal of VOCs. The Janus nanostructure was synthesized via an anisotropic growth method, composed of plasmonic nanoparticles, semiconductors, and metal organic frameworks (e.g., Au@ZnO@ZIF-8). It exhibits excellent selective detection to formaldehyde (HCHO, as a representative VOC) at room temperature over a wide range of concentrations (from 0.25 to 100 ppm), even in the presence of water and toluene molecules as interferences. In addition, HCHO was also found to be partially oxidized into non-toxic formic acid simultaneously with detection. The mechanism underlying this technology was unraveled by both experimental measurements and theoretical calculations: ZnO maintains the conductivity, while ZIF-8 improves the selective gas adsorption; the plasmonic effect of Au nanorods enhances the visible-light-driven photocatalysis of ZnO at room temperature.view more
Journal of Materials Chemistry A
X. He and W.-N. Wang
Semiconductors are the most widely used catalysts for CO2 photoreduction. However, their efficiencies are limited by low charge carrier density and poor CO2 activation. Towards solving these issues, a metal–organic framework (MOF)-based ternary nanocomposite was synthesized through self-assembly of TiO2/Cu2O heterojunctions via a microdroplet-based approach followed by in situ growth of Cu3(BTC)2 (BTC = 1,3,5-benzenetricarboxylate). With increased charge carrier density and efficient CO2 activation, the hybrid ternary nanocomposite exhibits a high CO2 conversion efficiency and preferential formation of CH4. Systematic measurements by using gas chromatography, photoluminescence spectroscopy, X-ray photoelectron spectroscopy, and time-resolved in situ diffuse reflectance infrared Fourier transform spectroscopy reveal that the semiconductor heterojunction and the coordinatively unsaturated copper sites within the hybrid nanostructure are attributable to the performance enhancements.view more
Environmental Science & Technology
D. Wang, S. E. Gilliland III, X. Yi, K. Logan, D. R. Heitger, H. R. Lucas, and W.-N. Wang
Efficient oxidation from arsenite [As(III)] to arsenate [As(V)], which is less toxic and more readily to be adsorbed by adsorbents, is important for the remediation of arsenic pollution. In this paper, we report a metal organic framework (MIL-100(Fe)) filter to efficiently remove arsenic from synthetic groundwater. With commercially available iron mesh as a substrate, MIL-100(Fe) is implanted through an in situ growth method. MIL-100(Fe) is able to capture As(III) due to its microporous structure, superior surface area, and ample active sites for As adsorption. This approach increases the localized As concentration around the filter, where Fenton-like reactions are initiated by the Fe2+/Fe3+ sites within the MIL-100(Fe) framework to oxidize As(III) to As(V). The mechanism was confirmed by colorimetric detection of H2O2, fluorescence, and electron paramagnetic resonance detection of ·OH. With the aid of oxygen bubbling and Joule heating, the removal efficiency of As(III) can be further boosted. The MIL-100(Fe)-based filter also exhibits satisfactory structural stability and recyclability. Notably, the adsorption capacity of the filter can be regenerated satisfactorily. Our results demonstrate the potential of this filter for the efficient remediation of As contamination in groundwater.
Catalysis Science & Technology
X. He, V. Nguyen, Z. Jiang, D. Wang, Z. Zhu, and W.-N. Wang
The ineffective removal of antibiotics from the aquatic environment has raised serious problems, including chronic toxicity and antibiotic resistance. Among the numerous strategies, photocatalytic degradation appears to be one of the promising methods to remove antibiotics. Semiconductors are the most widely used photocatalysts, whereas, their efficiencies still suffer from limited light absorption and poor charge separation. Given their exceptional properties, including a superior surface area and massive active sites, MOFs are excellent candidates for the formation of hierarchical nanostructures with semiconductors to address the above issues. In this study, highly-oriented one-dimensional (1D) MIL-100(Fe)/TiO2 nanoarrays were developed as photocatalysts for the first time (MIL = Materials Institute Lavoisier). The 1D structured TiO2 nanoarrays not only enable the direct and enhanced charge transport, but also permit easy recycling. With the in situ growth of MIL-100(Fe) on the TiO2 nanoarrays, the composite exhibits enhanced light absorption, electron/hole separation, and accessibility of active sites. As a result, up to 90.79% photodegradation efficiency of tetracycline, a representative antibiotic, by the MIL-100(Fe)/TiO2 composite nanoarrays was achieved, which is much higher than that of pristine TiO2 nanoarrays (35.22%). It is also worth mentioning that the composite nanoarrays demonstrate high stability and still exhibit high efficiency twice that of the pristine TiO2 nanoarrays even in the 5th run. This study offers a new strategy for the degradation of antibiotics by using 1D MOF-based nanocomposite nanoarrays.view more
Environmental Science: Nano
D. Wang, B. Zhu, X. He, Z. Zhu, G. Hutchins, P. Xu, and W.-N. Wang
Heating, ventilation, and air conditioning (HVAC) systems are among the most common methods to improve indoor air quality. However, after long-term operation, the HVAC filter can result in a proliferation of bacteria, which may be released into the filtered air subsequently. This issue can be addressed by designing antibacterial filters. In this study, we report an iron oxide nanowire-based filter fabricated from commercially available iron mesh through a thermal treatment. Under optimal conditions, the filter demonstrated a log inactivation efficiency of >7 within 10 seconds towards S. epidermidis (Gram-positive), a common bacterial species of indoor bioaerosol. 52% of bioaerosol cells can be captured by a single filter, which can be further improved to 98.7% by connecting five filters in tandem. The capture and inactivation capacity of the reported filter did not degrade over long-term use. The inactivation of bacteria is attributed to the synergic effects of hydroxyl radicals, electroporation, and Joule heating, which disrupt the cell wall and nucleoid of S. epidermidis, as verified by model simulations, fluorescence microscopy, electron microscopy, and infrared spectroscopy. The relative humidity plays an important role in the inactivation process. The filter also exhibited satisfactory inactivation efficiency towards E. coli (Gram-negative). The robust synthesis, low cost, and satisfactory inactivation performance towards both Gram-positive and Gram-negative bacteria make the filter demonstrated here suitable to be assembled into HVAC filters as an antibacterial layer for efficient control of indoor bioaerosols.view more
X. He and W.-N. Wang
The synthesis of metal–organic frameworks (MOFs) by using traditional wet-chemistry methods generally requires very long durations and still suffers from non-uniform heat and mass transfer within the bulk precursor solutions. Towards addressing these issues, a microdroplet-based spray method has been developed. In a typical spray process, an MOF's precursor solution is first atomized into microdroplets. These droplets serve as microreactors to ensure homogeneous mixing, fast evaporation, and rapid nucleation and crystal growth to form MOF particles. However, the fundamental MOF formation mechanisms by using this strategy have not been fully understood. In this work, the role of the operating pressure in the synthesis of a representative MOF (i.e., Cu(TPA)·(DMF); TPA: terephthalic acid, DMF: dimethylformamide) was systematically investigated. Detailed characterization showed that the pressure variations significantly affected both the morphologies and crystalline structures of Cu(TPA)·(DMF). Numerical simulations revealed that the morphology changes are mainly attributed to the variations in supersaturation ratios, which are caused by different microdroplet evaporation rates due to the regulation of operating pressure, while the crystalline structure variations are closely related to the dissociation of DMF molecules at lower operating pressures. Besides, the dissociation of DMF molecules decreased the surface area of the MOF crystals, but gave rise to massive coordinatively unsaturated metal sites, which greatly enhanced the interaction of CO2 with the MOF crystal and thus led to improved CO2 adsorption capacity and selectivity. The outcome of this work would contribute to the fundamental understanding of MOF synthesis using the microdroplet-based spray method.view more