Microwave dielectric heating of non-aqueous droplets in a microfluidic device for nanoparticle synthesis

Koziej, Dorota; Floryan, Caspar; Sperling, Ralph A.; Ehrlicher, Allen J.; Issadore, David; Westervelt, Robert; Weitz, David A.

doi:10.1039/c3nr00500c

Cited by 35 publications

(24 citation statements)

References 47 publications

(101 reference statements)

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“…I) TEM image of agglomerated WO 3 nanoparticles, II) diagram of microfluidic flow focusing reactor integrated with a microwave heater (adapted with permission. [108] Copyright 2013, Royal Society of Chemistry) D) Oxide nanoparticles synthesized using an ionic liquid-assisted technique in a microfluidic reactor. I) diagram of the microfluidic reactor, II) TEM image of a ZSM-5 nanoparticle, III) TEM image of β-FeOOH nanorods (adapted with permission.…”

Section: Metal Oxide Nanoparticlesmentioning

confidence: 99%

Microfluidic Synthesis of Semiconductor Materials: Toward Accelerated Materials Development in Flow

Campbell

Bateni

Volk

et al. 2020

Part & Part Syst Charact

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Semiconductors are intriguing due to their unique electrical properties, particularly the behavior of their electrons in the presence of different stimuli (e.g., electric field, magnetic field, light irradiation), which differ greatly from conducting (i.e., metals) and insulating materials. In insulators and semiconductors, the available electronic states are discontinuous, with the existence of a gap between the lower energy states, commonly referred to as the valence band (VB), and the higher energy states, known as the conduction band (CB). The distinguishing factor between these materials is the size of the energy difference between the highest energy state in the VB and the lowest energy state in the CB, called the band gap. In insulators, the band gap is very large, making it difficult, if not impossible, to cause an electron to move from the VB to the CB. By comparison, semiconductors possess narrow to moderate band gaps, implying that it is possible to introduce enough energy to an electron to cause it to move from the VB to the CB, enabling electron transfer, the use of high energy electrons, or the emission of energy (i.e., photons) when the electron returns from the CB to the VB. The wide range of industrial application-specific requirements demands versatility in the target characteristics of semiconductor materials (e.g., size, morphology, composition, band gap, emission wavelength), which are vastly different from those commonly used in thin-film transistors. Typically, the semiconductor materials synthesized for use in the above applications are particulate materials produced across a range of sizes spanning five orders of magnitude (from just a few nm to hundreds of µm), and can be divided into two overarching categories, nano-and microsized particulate materials. Nanosized semiconductor materials, due in large part to their miniscule dimensions, present a variety of intriguing characteristics not observed in microsized semiconductor particles. First and foremost, if the dimensions of the semiconductor material decrease below a certain threshold known as the Bohr radius, the absorption and emission energies become highly dependent on the particle size, a phenomenon known as quantum confinement. [28-30] Moreover, nanosized structures have significantly larger surface-to-volume ratios which increases the surface contribution to the total free energy of the semiconductor materials, making them highly soluble [29] and therefore much easier to process and handle. Thus far, nanosized semiconductor particles have been effectively utilized in sensors, [7] LEDs, [9] Controlled synthesis of semiconductor nano/microparticles has attracted sub stantial attention for use in numerous applications from photovoltaics to photo catalysis and bioimaging due to the breadth of available physicochemical and optoelectronic properties. Microfluidic material synthesis strategies have recently been demonstrated as an effective technique for rapid development, controlled synthesis, and continuous manufacturing of solutionpr...

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Section: Metal Oxide Nanoparticlesmentioning

confidence: 99%

Microfluidic Synthesis of Semiconductor Materials: Toward Accelerated Materials Development in Flow

Campbell

Bateni

Volk

et al. 2020

Part & Part Syst Charact

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“…This renders microwave synthesis a crucial option for well-defined particle fabrication in nanoscience and technology (Hilaire et al, 2014). However, little is still known about the growth mechanisms of metal oxides under the influence of microwaves (Moura et al, 2010;Koziej et al, 2013;Zeng et al, 2013). Therefore, we here provide a broader insight into the crucial influence of a set of different synthesis parameters.…”

Section: Introductionmentioning

confidence: 97%

Microwave-Hydrothermal Tuning of Spinel-Type Co3O4 Water Oxidation Catalysts

et al. 2020

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Water oxidation is the bottleneck reaction for overall water splitting as a direct and promising strategy toward clean fuels. However, the development of robust and affordable heterogeneous water oxidation catalysts remains challenging, especially with respect to the wide parameter space of synthesis and resulting material properties. Oxide catalysts performance in particular has been shown to depend on both synthetic routes and applied catalytic test methods. We here focus on spinel-type Co 3 O 4 as a representative case for an in-depth study of the influence of rather subtle synthetic parameter variations on the catalytic performance. To this end, a series of Co 3 O 4 samples was prepared via time-saving and tunable microwave-hydrothermal synthesis, while systematically varying a single parameter at a time. The resulting spinel-type catalysts were characterized with respect to key materials properties, including crystallinity, oxidation state and surface area using a wide range of analytical methods, such as PXRD, Raman/IR, XAS and XPS spectroscopy. Their water oxidation activity in electrocatalytic and chemical oxidation setups was then compared and correlated with the obtained catalyst properties. Both water oxidation methods displayed related trends concerning favorable synthetic parameters, namely higher activity for lower synthesis temperatures, lower precursor concentrations, addition of hydrogen peroxide and shorter ramping and reaction times, respectively. In addition to the surface area, structural features such as disorder were found to be influential for the water oxidation activity. The results prove that synthetic parameter screening is essential for optimal catalytic performance, given the complexity of the underlying performance-properties relationships.

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“…The nonaqueous sol-gel method to the best of our knowledge has only in one report been described to be carried out in a microfluidic system. Koziej et al (Koziej et al, 2013) synthesized tungsten oxide nanoparticles while heating the reaction mixture with a microwave device and investigated the temperature evolution in the droplets with in situ IR-spectroscopy. Koziej et al showed that fast-heated droplets bearing a homogeneous temperature result in homogenous formation and growth conditions, achieving rather uniform and crystalline particles.…”

Section: Introductionmentioning

confidence: 99%

Microfluidic synthesis of metal oxide nanoparticles via the nonaqueous method

Stolzenburg

Lorenz

Dietzel

et al. 2018

Chemical Engineering Science

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Microfluidic synthesis allows for a good control of the particle formation conditions while minimizing the consumption of material. In this study, we exploited these advantages for the nonaqueous synthesis of TiO 2 , ZnO and CeO 2 nanoparticles in a closed micro droplet reactor which resulted in well-defined particle structures. Monodisperse droplets are generated in microfluidic flow-focusing area and

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Microwave dielectric heating of non-aqueous droplets in a microfluidic device for nanoparticle synthesis

Cited by 35 publications

References 47 publications

Microfluidic Synthesis of Semiconductor Materials: Toward Accelerated Materials Development in Flow

Microfluidic Synthesis of Semiconductor Materials: Toward Accelerated Materials Development in Flow

Microwave-Hydrothermal Tuning of Spinel-Type Co3O4 Water Oxidation Catalysts

Microfluidic synthesis of metal oxide nanoparticles via the nonaqueous method

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