The Laboratory for Energy Materials and Nano-Biomedicine develops advanced materials for fundamental studies on structure-property relationships and applications in energy and biomedicine.
A solar-powered energy generator via transparent multilayer photothermal thin films
A fundamental challenge in energy sustainability is efficient utilization of solar source towards energy-neutral systems. The current solar cell technologies have been most widely employed to achieve this goal, but limited to a single-layer 2D surface. To harvest solar light more efficiently, we have developed a multilayer system capable of harvesting solar light in a cuboid (5 x 5 x 15 cm3) through transparent photothermal thin films of iron oxide and a porphyrin compound (Fig. 1). Analogous to a multilayer capacitor, an array of transparent, spectral selective, photothermal thin films allows white light to penetrate them, not only collecting photon energy in a 3D space, but generating sufficient heat on each layer with significantly increased total surface area. The multilayer system extends another dimensionality in solar harvesting and paves a new path to energy generation for the energy-neutral system. In this fashion, thermal energy is generated via a multilayer photothermal system that functions as an efficient solar collector, energy converter and generator with high energy density. The energy densities inside the cuboid with both types of thin films have reached 1.48×108 J/m3 via multilayers. The solar-activated thermal energy generator in a cuboid can produce heat without any power supply and reach a maximum temperature of 76.1 °C (Fig. 1). With a constant incoming white light (0.4W⋅ cm-2), the thermal energy generated can be amplified twelvefold and increased from 5074.3 J (one layer) to 55, 465.8 J (ten layers) for the Fe3O4@Cu2-xS system, and increased from 3826.3 J (one layer) to 56, 143.9 J (ten layers) for chlorophyllin system, both have more than tenfold of increase. The solar photothermal efficiency (η) of the system is greater than 60 % with 10 layers of transparent films. These experimental results demonstrate a concept of “Thermal Generator” that will show promise in major energy-applications.
Source of Support: NSF CMMI-1635089 and CMMI-1953009
Related Publications: Solar harvesting through multilayer spectral selective iron oxide and porphyrin transparent thin films for photothermal energy generation, Mengyao Lyu, Jou Lin, John Krupczak, and Donglu Shi, Advanced Sustainable Systems, 2021.
Solar-energy harvesting building skin via transparent thin films with photothermal/photovoltaic dual modality for next generation energy-free civic structures
A building skin has been conventionally considered as a weather-resistive barrier without any active functions. This project revolutionizes this traditional concept by structurally transforming the building skin to a versatile energy network capable of harvesting sunlight according to the seasonal changes for energy efficiency. In this new concept, a building skin is considered multifunctionally active for natural energy harvesting, conversion, and utilization. The glass-based high-rise building skins provide ideal transparent substrates for device architecture of energy harvesting nanoscale thin films. A nanostructured thin film on building skin is engineered to offer two major functions: photovoltaic or photothermal, switched alternatively depending on the seasonal needs. In summer, the photovoltaic effect of the coating consumes most of the solar infrared therefore less cooling is required. In winter, the slight increase in skin temperature by the photothermal coating can lead to lowered heat loss from room interior. The goal of this research is to develop a multifunctional building skin capable of efficient solar harvesting for different energy outputs, be it thermal or electric via dual-modality, spectral selective, seasonably altered. Principally, both photothermal and photovoltaic films share the same optical characteristics: strong UV/NIR absorptions with high visible transmittance, the only difference is the output energy form. The outcomes of the research activities will address the national needs in energy sustainability by entirely transforming the landscape of architectural engineering, civic system design, and energy saving strategy.
Source of Support: CMMI – 1953009 ECI-Engineering for Civil Infrastructure
Related Publications: Spectral selective and photothermal nano structured thin films for energy efficient windows
The Photothermal Effects of Iron Oxide Nanoparticles on Energy Efficient Windows
A new concept of thermal insulation, namely, optical thermal insulation is achieved without any intervention medium such as air or argon, as often used in the conventional glazing technologies. Various transparent, spectral-selective photothermal thin films, based on iron oxide and porphyrin compounds, not only result in sufficient solar light harvest in a wide spectrum, but also allow for efficient conversion of solar light to heat in the non-visible region. If a spectral-selective thin film is applied on a window surface, the skin surface temperature can be increased from 25 °C to > 50 °C via the photothermal effect. This will in turn effectively reduce the thermal energy loss from the interior, based on the so-called optical thermal insulation. Both Fe3O4@Cu2-xS and the porphyrin compounds are found to exhibit strong UV and NIR absorptions, but high visible transmittance. Upon coating the inner surface of the window glass with a photothermal film, under solar irradiation, the inner surface is heated to reduce the temperature difference, DT, between the single-pane and room interior. This reduction in DT will effectively lower heat transfer through the building skin, therefore achieving the goal of energy saving without double- or triple- glazing. These photothermal materials are abundant in nature and environmentally friendly. The fundamental photothermal mechanisms are identified for both iron oxide and porphyrin compounds in terms of their electronic structures. The novel concept paves a new way for thermal insulation without insulating materials. The engineering implications show great promise in both energy and materials savings for sustainability.
Source of Support: NSF CMMI-1635089
Processing of soft magnetic nano-crystalline powders directly from as-spun Fe77Ni5.5Co5.5Zr7B4Cu ribbon via ball mill without devitrification
A common microstructural feature of the soft magnetic materials is the ferromagnetic nano-crystallites (~10-20 nm) embedded in an amorphous matrix, whose average size is considerably smaller than the correlation length, L, resulting in a unique combination of large magnetization, high permeability, and an extremely low coercive field. The magnetic softness has been explained by the random anisotropy model which predicts that the local magneto-crystalline anisotropy, K, will have a strong dependence of the gran size, D: K ~ (D/L). As shown by several studies, the correlation lengths of Fe-based alloys are between 40-120 nm for grain size well below 20 nm. In the amorphous state, the structure crystalline features are absent (it is structurally highly isotropic), therefore the magneto-crystalline anisotropy will become negligible, resulting in extremely soft magnetic properties. This project is focused on developing the soft magnetic alloys to provide a highly power dense magnetic core with low losses. The research includes rapid solidification, crystallization, and fine powder processing for high-temperature soft magnetic materials. By developing ferromagnetic nano-crystallites (~10 nm) embedded in an amorphous matrix, which are considerably shorter than the correlation length, a soft magnetic material is obtained with superb magnetic properties and extremely low cohesive fields.
Source of Support: Ohio Department of Higher Education (CWRU RES511312 sub ODHE)
Disinfection of COVID-19 Coronavirus via Cold Plasma Treatment
COVID-19 is known to be transmitted through respiratory droplets that originate from coughs and sneezes of an infected person. Infectious droplets can land on surfaces surrounding an infected individual, including bedding, floors, walls, and objects that may subsequently be contacted by uninfected individuals. Methods to prevent such transmission have been recommended by CDC, including the use of hand sanitizer, alcohol, and a diluted solution of sodium hypochlorite. In practice, most of the disinfectants are in liquid or gel forms that may apply directly on skins and hard surfaces. Soft surfaces of clothing, packaging, and everyday mail are, however, not easily disinfected by applying WET disinfectants. It is therefore critical to develop a DRY treatment that can be easily and frequently applied on these everyday items. This research investigates the effect of cold atmospheric plasma on virus disinfection. Plasma is matter in the form of ions and electrons with significant energies, thus viewed as reactive species that can bombard any cell surfaces resulting in significant structural damages. A gas (air, nitrogen, argon, oxygen) can be electrified and charged with freely moving electrons in both the negative and positive state. These plasma radicals can interrupt a biological system at different levels depending upon the power applied and treatment duration to: induce amino acid oxidation; reduce enzyme activity, damage DNA and RNA, and break cell membrane. These effects will all contribute to viral transfection, however to different degrees. By studying the transfection efficiency, we will be able to determine the activity of the virus that has been treated by plasma under given conditions. This research is carried out in collaboration with Dr. Paul Spearman, Director of Division of Infectious Diseases, Cincinnati Children’s Hospital Medical Center.
Source of Support: NSF 2029268 IIP - PFI-Partnerships for Innovation
Highly Efficient in Vivo Targeting of the Pulmonary Endothelium Using Novel Modifications of Polyethylenimine: An Importance of Charge
There is a critical need for the development of effective strategies for small molecule or non-viral gene therapy for tailored treatment at the molecular level. Nanotechnology provides a promising avenue for tailored treatment of these diseases, overcoming the struggles of current regimens. In collaboration with Dr. Vladimir V. Kalinichenko from Cincinnati Children’s Hospital Research Foundation, we jointly develop novel formulations of cationic based, non-viral nanoparticles that efficiently target the pulmonary microvascular network for the delivery of nucleic acids. Nanoparticles are created by functionalizing low molecular weight polyethylenimine (PEI) with biological fatty acids and carboxylate terminated poly(ethylene glycol) (PEG) through a one-pot EDC/NHS reaction. These polyplexes provide a powerful basis for selective delivery of nucleic acids for therapeutic treatments.
Fig. C) Immunofluorescent images of lung microvasculature and large vessels for (−)- and (+)-coated polyplexes. (C-b,b′) nanoparticle only channel for (C-a,a′) the respective field of view. (C-c,c′) Nanoparticle only channel for (+) polyplexes showing (C-c) high affinity within microvasculature and (c′) reduced targeting within large vessels. IF of (−) and (+) polyplexes are taken from different samples imaged under the same acquisition parameters.
Source of Support: Cincinnati Children’s Hospital
Professor, CEAS - Materials Science & Engineering
493 Rhodes Hall
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