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Recent Submissions

  • Interfaces between Pb-Free Double Perovskite Cs2NaBiI6 and MXenes Sc2CO2 and Sc2C(OH)2

    Albar, Arwa; Schwingenschlögl, Udo (The Journal of Physical Chemistry Letters, American Chemical Society (ACS), 2022-01-19) [Article]
    First-principles calculations are used to explore the electronic properties of the interfaces between the Pb-free double perovskite Cs2NaBiI6 and the MXenes Sc2CO2 and Sc2C(OH)2. The effect of the termination group on the stability, ionization potential, electron affinity, and band alignment is investigated. We find a type II band alignment at the Cs2NaBiI6/Sc2CO2 interface, which permits charge transfer, and a type III band alignment at the Cs2NaBiI6/Sc2C(OH)2 interface, which results in electron–hole recombination. Sc2CO2 turns out to be highly promising for solar cell applications due to an almost ideal ionization potential difference to Cs2NaBiI6.
  • Effects of Vertical Molecular Stratifications and Microstructures on the Properties of Fullerene-Free Organic Solar Cells

    Peña, Top Archie Dela; Ma, Ruijie; Sharma, Anirudh; Xing, Zengshan; Jin, Zijing; Wang, Jiannong; Baran, Derya; Weng, Lu-Tao; Yan, He; Wong, Kam Sing (Advanced Photonics Research, Wiley, 2022-01-18) [Article]
    From the past years, the most commonly reported state-of-the-art binary bulk heterojunction organic solar cells (OSCs) are mostly based on mixtures of polymer donors and fullerene-free acceptors (polymer:NFA). However, along with it are a number of contradictory propositions, including (but not limited to) strategies to reduce energy loss and improve photocurrent generation through energy level alignments. Due to the resulting high similarity of molecular fragments from polymer:NFA heterojunctions, the effects of vertical molecular stratification are not yet well studied. Herein, the time-of-flight secondary ion mass spectrometry (ToF-SIMS) molecular depth profiling reveals a vertical stratification in PM6:IT-4Cl and illustrates how it can significantly influence the photovoltaic properties. The said inhomogeneity is also bound to introduce microstructure variations within device active layers. Consequently, it is systematically demonstrated how thin-film microstructures can influence optoelectronic properties, wherein important metrics (e.g., energy losses and molecular energy offsets) are highly dependent. Thus, the understanding from this work provides foundations for more precise development of strategies to further advance OSC technology in future studies.
  • Self-Assembly and Regrowth of Metal Halide Perovskite Nanocrystals for Optoelectronic Applications

    Liu, Jiakai; Zheng, Xiaopeng; Mohammed, Omar F.; Bakr, Osman (Accounts of Chemical Research, American Chemical Society (ACS), 2022-01-16) [Article]
    Conspectus Over the past decade, the impressive development of metal halide perovskites (MHPs) has made them leading candidates for applications in photovoltaics (PVs), X-ray scintillators, and light-emitting diodes (LEDs). Constructing MHP nanocrystals (NCs) with promising optoelectronic properties using a low-cost approach is critical to realizing their commercial potential. Self-assembly and regrowth techniques provide a simple and powerful “bottom-up” platform for controlling the structure, shape, and dimensionality of MHP NCs. The soft ionic nature of MHP NCs, in conjunction with their low formation energy, rapid anion exchange, and ease of ion migration, enables the rearrangement of their overall appearance via self-assembly or regrowth. Because of their low formation energy and highly dynamic surface ligands, MHP NCs have a higher propensity to regrow than conventional hard-lattice NCs. Moreover, their self-assembly and regrowth can be achieved simultaneously. The self-assembly of NCs into close-packed, long-range-ordered mesostructures provides a platform for modulating their electronic properties (e.g., conductivity and carrier mobility). Moreover, assembled MHP NCs exhibit collective properties (e.g., superfluorescence, renormalized emission, longer phase coherence times, and long exciton diffusion lengths) that can translate into dramatic improvements in device performance. Further regrowth into fused MHP nanostructures with the removal of ligand barriers between NCs could facilitate charge carrier transport, eliminate surface point defects, and enhance stability against moisture, light, and electron-beam irradiation. However, the synthesis strategies, diversity and complexity of structures, and optoelectronic applications that emanate from the self-assembly and regrowth of MHPs have not yet received much attention. Consequently, a comprehensive understanding of the design principles of self-assembled and fused MHP nanostructures will fuel further advances in their optoelectronic applications. In this Account, we review the latest developments in the self-assembly and regrowth of MHP NCs. We begin with a survey of the mechanisms, driving forces, and techniques for controlling MHP NC self-assembly. We then explore the phase transition of fused MHP nanostructures at the atomic level, delving into the mechanisms of facet-directed connections and the kinetics of their shape-modulation behavior, which have been elucidated with the aid of high-resolution transmission electron microscopy (HRTEM) and first-principles density functional theory calculations of surface energies. We further outline the applications of assembled and fused nanostructures. Finally, we conclude with a perspective on current challenges and future directions in the field of MHP.
  • Study of the Effect of Research Octane Number on the Auto-Ignition of Lubricant Oil Surrogates (n-Hexadecane)

    Maharjan, Sumit; Elbaz, Ayman M.; Roberts, William L. (ACS Omega, American Chemical Society (ACS), 2022-01-12) [Article]
    Engine oil is considered one of the sources for pre-ignition in downsized boosted direct injection spark-ignited engines. When interacting with fuel sprayed in the combustion chamber, engine oil forms an ignitable mixture and can cause an ignition event before firing the spark plug. Because high research octane number (RON) fuels are difficult to auto-ignite and tend to suppress the knock in an internal combustion engine, studying their interaction with engine oil is essential. Hence, in the current study, a suitable lubricant oil surrogate, namely, n-hexadecane, is mixed with iso-octane and n-heptane at different concentrations to investigate the auto-ignition behavior at elevated pressures. Five sets of fuels (PRF0, PRF20, PRF50, PRF80, and PRF100) were prepared to get a wide range of RONs and blended with n-hexadecane at 15, 25, 35, and 45% mixture concentrations (vol %). These experiments were conducted in a constant volume combustion chamber, keeping the initial temperature constant at 300 °C. A single droplet of the mixture was suspended on a thermocouple bead to record the droplet’s lifetime temperature. It was observed that hexadecane mixed with PRF0, PRF20, PRF50, and PRF80 showed similar auto-ignition behaviors. The time of ignition (TI) for these mixtures initially increased until 25% concentration of the fuel in n-hexadecane, and further addition of fuels to 35% and higher concentrations showed a gradual decrease in TI. Ignition of mixtures with 35% and 45% fuel concentrations is attributed to n-heptane, as its low temperature chemistry is the dominant factor in its high reactivity compared to iso-octane. TI increased with the increasing concentration of PRF100 mixtures in hexadecane, unlike other PRF fuels tested in this study. This is because iso-octane is a high RON fuel with a higher auto-ignition temperature, making it challenging to auto-ignite.
  • Using Triethylborane to Manipulate Reactivity Ratios in Epoxide-Anhydride Copolymerization: Application to the Synthesis of Polyethers with Degradable Ester Functions

    Chidara, Vamshi Krishna; Gnanou, Yves; Feng, Xiaoshuang (Molecules, MDPI AG, 2022-01-11) [Article]
    The anionic ring-opening copolymerization (ROCOP) of epoxides, namely of ethylene oxide (EO), with anhydrides (AH) generally produces strictly alternating copolymers. With triethylborane (TEB)-assisted ROCOP of EO with AH, statistical copolymers of high molar mass including ether and ester units could be obtained. In the presence of TEB, the reactivity ratio of EO (rEO), which is normally equal to 0 in its absence, could be progressively raised to values lower than 1 or higher than 1. Conditions were even found to obtain rEO equal or close to 1. Samples of P(EO-co-ester) with minimal compositional drift could be synthesized; upon basic degradation of their ester linkages, these samples afforded poly(ethylene oxide) (PEO) diol samples of narrow molar mass distribution. In other cases where rEO were lower or higher than 1, the PEO diol samples eventually isolated after degradation exhibited a broader distribution of molar masses because of the compositional drift of initial P(EO-co-ester) samples.
  • Air-Processable and Thermally Stable Hole Transport Layer for Non-Fullerene Organic Solar Cells

    Bertrandie, Jules; Sharma, Anirudh; Gasparini, Nicola; Rosas Villalva, Diego; Paleti, Sri Harish Kumar; Wehbe, Nimer; Troughton, Joel; Baran, Derya (ACS Applied Energy Materials, American Chemical Society (ACS), 2022-01-10) [Article]
    Power conversion efficiencies (PCEs) of organic solar cells (OSCs) have now surpassed 19%. This has led to an increased focus on developing devices using methods and materials that are scalable, processable under ambient air atmospheres, and stable. However, current materials fall short of the essential requirements for stability and processability needed for cost-effective large-scale fabrication of high-performing OSCs. Here, we report a hybrid solution-processable hole transport layer (HTL) based on tantalum-doped tungsten oxide (TaWOx) nanoparticles and poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) demonstrating good wettability over the hydrophobic active layer. N-i-p-type OSCs that are processed fully under ambient conditions, based on a polymer donor and a non-fullerene acceptor incorporating a combined TaWOx-PEDOT:PSS layer as HTL deliver a power conversion efficiency of 8.6%. OSCs utilizing the TaWOx-PEDOT:PSS HTL demonstrate improved thermal stability compared to devices based on the previously reported solution-processed MoOx-PEDOT:PSS HTL, which was found to severely degrade upon thermal treatment at 85 °C. Photoelectron spectroscopy and secondary ion mass spectrometry (SIMS) reveal that the MoOx-PEDOT:PSS HTL is prone to thermally induced intermixing with the underlying active layer, resulting in unfavorable changes in the interfacial energetics. No significant heat-induced changes are observed in the case of the TaWOx-PEDOT:PSS HTL when annealed up to 120 °C, imparting enhanced thermal stability to the devices. Improved wettability on hydrophobic surfaces, combined with air processability and enhanced thermal stability makes TaWOx-PEDOT:PSS a promising HTL material for fabricating stable NFA solar cells using roll-to-roll compatible printing and coating methods.
  • A Universal Co-Solvent Evaporation Strategy Enables Direct Printing of Perovskite Single Crystals for Optoelectronic Device Applications

    Corzo Diaz, Daniel Alejandro; Wang, Tonghui; Gedda, Murali; Yengel, Emre; Khan, Jafar Iqbal; Li, Ruipeng; Niazi, Muhammad Rizwan; Huang, Zhengjie; Kim, Taesoo; Baran, Derya; Sun, Dali; Laquai, Frédéric; Anthopoulos, Thomas D.; Amassian, Aram (Advanced Materials, Wiley, 2022-01-10) [Article]
    Solution-processed metal halide perovskite single crystals (SCs) are in high demand for a growing number of emerging device applications due to their superior optoelectronic properties compared to polycrystalline thin films. However, the historical focus on thin film optoelectronic and photovoltaic devices explains the absence of methods suitable for facile, scalable and high throughput fabrication of precision-engineered and positioned SCs and arrays. Here, we present a universal co-solvent evaporation (CSE) strategy by which perovskite SCsand arrays are produced directly on substrates from individual drying droplets in a single step within minutes at room temperature. The CSE strategy successfully guides supersaturation of drying droplets to suppress all unwanted crystallization pathways and is shown to produce SCsof a wide variety of three-dimensional (3D), quasi-two dimensional (2D), and mixed cation/halideperovskites. The drying droplet approach works with commonly used solvents, making it universal. Importantly, the CSE strategy ensures the SC consumes the precursor in its entirety, leaving little to no residue on substrates, which is crucial for enabling fabrication of SC arrays on large areas via printing and coating techniques. We go on to demonstrate direct on-chip fabrication of 3D and quasi-2D perovskite photodetector devices with outstanding performance. Our approach shows that metal halide perovskite SCs can now be produced on substrates from a drying solution via a wide range of solution processing methods, including microprinting and scalable, high throughput coating methods.
  • Crack tip fields in a fiber-reinforced hyperelastic sheet: Competing roles of fiber and matrix stiffening

    Liu, Yin; Moran, Brian (Mechanics Research Communications, Elsevier, 2022-01-10) [Article]
    Fiber-reinforced materials are widely observed in biological tissue such as human arteries and tendons. Characterizing the influence of fibers on crack-tip fields in such nonlinear materials undergoing large deformation is an important precursor to understanding damage evolution and fracture or tearing. In this paper, we present asymptotic crack tip fields in a fiber-reinforced hyperelastic sheet and explore the competing roles of fiber and matrix stiffening. A generalized neo-Hookean model and a power-law model are employed to characterize the behavior of the matrix and fibers, respectively. We show that the asymptotic crack-tip fields are mainly determined by the phase with largest degree of stiffening. For example, when the stiffening effect of fibers is much larger than that of the matrix, the crack tip fields are determined by the constitutive behavior of fibers, and the wire model and the fabric model reasonably characterize the deformation and stress near the crack tip. On the contrary, if the matrix stiffening is larger than that of the fibers, we show that the crack tip fields approach those of a pure matrix material. The asymptotic results are complemented by finite element simulations which show good agreement. These findings may shed light on material damage at a crack tip in fiber reinforced materials.
  • Porous Ti3C2Tx MXene Membranes for Highly Efficient Salinity Gradient Energy Harvesting

    Hong, Seunghyun; El Demellawi, Jehad K.; Lei, Yongjiu; Liu, Zhixiong; Marzooqi, Faisal Al; Arafat, Hassan A.; Alshareef, Husam N. (ACS Nano, American Chemical Society (ACS), 2022-01-09) [Article]
    Extracting osmotic energy through nanoporous membranes is an efficient way to harvest renewable and sustainable energy using the salinity gradient between seawater and river water. Despite recent advances of nanopore-based membranes, which have revitalized the prospect of blue energy, their energy conversion is hampered by nanomembrane issues such as high internal resistance or low selectivity. Herein, we report a lamellar-structured membrane made of nanoporous Ti<sub>3</sub>C<sub>2</sub>T<sub><i>x</i></sub> MXene sheets, exhibiting simultaneous enhancement in permeability and ion selectivity beyond their inherent trade-off. The perforated nanopores formed by facile H<sub>2</sub>SO<sub>4</sub> oxidation of the sheets act as a network of cation channels that interconnects interplanar nanocapillaries throughout the lamellar membrane. The constructed internal nanopores lower the energy barrier for cation passage, thereby boosting the preferential ion diffusion across the membrane. A maximum output power density of the nanoporous Ti<sub>3</sub>C<sub>2</sub>T<sub><i>x</i></sub> MXene membranes reaches up to 17.5 W·m<sup>-2</sup> under a 100-fold KCl gradient at neutral pH and room temperature, which is as high as by 38% compared to that of the pristine membrane. The membrane design strategy employing the nanoporous two-dimensional sheets provides a promising approach for ion exchange, osmotic energy extraction, and other nanofluidic applications.
  • Focusing and defocusing of tropical cyclone generated waves by ocean current refraction

    Sun, Rui; Villas Bôas, Ana B.; Subramanian, Aneesh C.; Cornuelle, Bruce D.; Mazloff, Matthew R.; Miller, Arthur J.; Langodan, Sabique; Hoteit, Ibrahim (Journal of Geophysical Research: Oceans, American Geophysical Union (AGU), 2022-01-07) [Article]
    Waves generated by tropical cyclones can have devastating effects on coastal regions. However, the role of ocean currents in modifying wave amplitudes, wavelengths, and directions is commonly overlooked in wave forecasts, despite the fact that these interactions can lead to extreme wave conditions. Here, we use satellite observations and wave modeling to quantify the effects of ocean currents on the surface waves generated during a tropical cyclone event in the Arabian Sea. As a case study, this paper documents beams of wave heights originating from the eyewall of a tropical cyclone caused by current-induced refraction. Alternating regions of high and low wave heights in the model simulations are consistent with observations and extend for thousands of kilometers all the way to 100 m isobath. Our results highlight the importance of accounting for wave refraction by currents in order to accurately predict the impact of tropical cyclone generated waves on coastal regions.
  • Scalable CMOS-BEOL compatible AlScN/2D Channel FE-FETs

    Kim, Kwan-Ho; Oh, Seyong; Fiagbenu, Merrilyn Mercy Adzo; Zheng, Jeffrey; Musavigharavi, Pariasadat; Kumar, Pawan; Trainor, Nicholas; Aljarb, Areej; Wan, Yi; Kim, Hyong Min; Katti, Keshava; Tang, Zichen; Tung, Vincent; Redwing, Joan; Stach, Eric A.; III, Roy H. Olsson; Jariwala, Deep (arXiv, 2022-01-06) [Preprint]
    Intimate integration of memory devices with logic transistors is a frontier challenge in computer hardware. This integration is essential for augmenting computational power concurrently with enhanced energy efficiency in big-data applications such as artificial intelligence. Despite decades of efforts, reliable, compact, energy efficient and scalable memory devices are elusive. Ferroelectric Field Effect Transistors (FE-FETs) are a promising candidate but their scalability and performance in a back-end-of-line (BEOL) process remain unattained. Here, we present scalable BEOL compatible FE-FETs using two-dimensional (2D) MoS2 channel and AlScN ferroelectric dielectric. We have fabricated a large array of FE-FETs with memory windows larger than 7.8 V, ON/OFF ratios of greater than 10^7, and ON current density greater than 250 uA/um, all at ~80 nm channel lengths. Our devices show stable retention up to 20000 secs and endurance up to 20000 cycles in addition to 4-bit pulse programmable memory features thereby opening a path towards scalable 3D hetero-integration of 2D semiconductor memory with Si CMOS logic.
  • 14 GHz Schottky Diodes using a p -Doped Organic Polymer

    Loganathan, Kalaivanan; Scaccabarozzi, Alberto D.; Faber, Hendrik; Ferrari, Federico; Bizak, Zhanibek; Yengel, Emre; Naphade, Dipti R.; Gedda, Murali; He, Qiao; Solomeshch, Olga; Adilbekova, Begimai; Yarali, Emre; Tsetseris, Leonidas; Salama, Khaled N.; Heeney, Martin; Tessler, Nir; Anthopoulos, Thomas D. (Advanced Materials, Wiley, 2022-01-06) [Article]
    The low carrier mobility of organic semiconductors and the high parasitic resistance and capacitance often encountered in conventional organic Schottky diodes, hinder their deployment in emerging radio frequency (RF) electronics. Here we overcome these limitations by combining self-aligned asymmetric nanogap electrodes (∼25 nm) produced by adhesion-lithography, with a high mobility organic semiconductor and demonstrate RF Schottky diodes able to operate in the 5G frequency spectrum. We used C<sub>16</sub> IDT-BT, as the high hole mobility polymer, and studied the impact of p-doping on the diode performance. Pristine C<sub>16</sub> IDT-BT-based diodes exhibit maximum intrinsic and extrinsic cutoff frequencies (f<sub>C</sub> ) of >100 and 6 GHz, respectively. This extraordinary performance is attributed primarily to the planar nature of the nanogap channel and the diode's small junction capacitance (< 2 pF). Doping of C<sub>16</sub> IDT-BT with the molecular p-dopant C<sub>60</sub> F<sub>48</sub> , improves the diode's performance further by reducing the series resistance resulting to intrinsic and extrinsic f<sub>C</sub> of >100 and ∼14 GHz respectively, while the DC output voltage of a RF rectifier circuit increases by a tenfold. Our work highlights the importance of the planar nanogap architecture and paves the way for the use of organic Schottky diodes in large-area radio frequency electronics of the future. This article is protected by copyright. All rights reserved.
  • Ultrahigh-flux Nanoporous Graphene Membrane for Sustainable Seawater Desalination Using Low-grade Heat

    Lu, Dongwei; Zhou, Zongyao; Wang, Zhihong; Ho, Duc Tam; Sheng, Guan; Chen, Long; Zhao, Yumeng; Li, Xiang; Cao, Li; Schwingenschlögl, Udo; Ma, Jun; Lai, Zhiping (Advanced Materials, Wiley, 2022-01-06) [Article]
    Membrane distillation has attracted great attention in the development of sustainable desalination and zero-discharge processes because of its possibility to recover 100% water and the potential to integrate with low-grade heat such as solar energy. However, the conventional membrane structures and materials afford limited flux thus obstructing its practical application. Here we report ultrathin nanoporous graphene membranes by selectively forming thin graphene layers on the top edges of highly porous anodic alumina oxide support, which creates short and fast transport pathways for water vapor but not liquid. The process avoids the challenging pore-generation and substrate-transfer processes required to prepare regular graphene membranes. In the direct contact membrane distillation mode under a mild temperature pair of 65°C /25°C, the nanoporous graphene membranes show an average water flux of 421.7 Lm<sup>-2</sup> h<sup>-1</sup> with over 99.8% salt rejection, which is an order of magnitude higher than any reported polymeric membranes. The mechanism for high water flux is revealed by detailed characterizations and theoretical modeling. Outdoor field tests using Red Sea water heated under direct sunlight radiation show that the membranes have an average water flux of 86.3 Lm<sup>-2</sup> h<sup>-1</sup> from 8 am. to 8 pm., showing a great potential for real applications in seawater desalination. This article is protected by copyright. All rights reserved.
  • Operando Monitoring and Deciphering the Structural Evolution in Oxygen Evolution Electrocatalysis

    Zuo, Shouwei; Wu, Zhi-Peng; Zhang, Huabin; Lou, Xiong Wen (David) (Advanced Energy Materials, Wiley, 2022-01-05) [Article]
    The oxygen evolution reaction (OER) acts as the bottleneck of some crucial energy conversion and storage technologies involving water electrolysis, CO2 electrolysis, and metal-air batteries, among others. The challenging sluggish reaction kinetics of the OER can be overcome via developing highly efficient electrocatalysts, which experience a dynamic structural evolution process during the reaction. However, the reaction mechanism of the structural transformation of electrocatalysts during the OER and the structure-activity correlation in understanding the real active sites remain elusive. Fortunately, operando characterizations offer a platform to study the structural evolution processes and the reaction mechanisms of OER electrocatalysts. In this review, using several in situ/operando techniques some recent advances are elaborated with emphases on tracking the structural evolution processes of electrocatalysts, recording the reaction intermediates during electrocatalysis, and building a link between the structure and activity/stability of electrocatalysts. Moreover, theoretical considerations are also discussed to assist operando characterization understanding. Finally, some perspectives are provided which are expected to be helpful to tackle the current challenges in operando monitoring and unraveling the reaction mechanisms of OER electrocatalysts.
  • Bimetallic Cu(I)/Rh(II) Relay Catalysis for Multicomponent Polymerization through Carbene Intermediates

    Wang, Ying; Zhu, Linlin; Chen, Wenhao; Zhou, Zhi; Zhang, Zhen; Hadjichristidis, Nikos (Macromolecules, American Chemical Society (ACS), 2022-01-05) [Article]
    A highly efficient and multicomponent step-growth polymerization via carbene intermediates is established by bimetallic relay catalytic systems. This strategy, which provides a facile synthetic pathway to novel luminescent polysulfonamides, could overcome the limitation on the choice of carbene monomers and their difficulty in achieving high-molecular-weight polymers. The polymerizations occur through a tandem Cu(I)-catalyzed click reaction and an Rh(II)-catalyzed carbene 1,3-insertion reaction. The high reactivity of Rh(II)-bonded imino carbene intermediates allows a wide range of reactivity with various carboxylic acids, alcohols, and phenols. These results point to an untapped pathway for the use of metal carbene intermediates to construct new macromolecules.
  • Organic Acid Etching Strategy for Dendrite Suppression in Aqueous Zinc-Ion Batteries

    Wang, Wenxi; Huang, Gang; Wang, Yizhou; Cao, Zhen; Cavallo, Luigi; Hedhili, Mohamed N.; Alshareef, Husam N. (Advanced Energy Materials, Wiley, 2022-01-05) [Article]
    Aqueous zinc ion batteries (AZIBs) represent a promising technology for grid-scale energy storage due to their innate safety, low cost, and environmental friendliness. However, planar Zn foil intrinsically suffers from limited ion and electron transport pathways, poor wettability, and surface passivation, preventing the homogenous deposition of metallic Zn and poor durability of AZIBs. Herein, a 3D Zn foil with hierarchical porous architecture is developed through a facile non-aqueous organic acid etching strategy. The 3D Zn anode is pore-rich and cavity-rich, leading to significantly enhanced accessibility to aqueous electrolytes. Accordingly, this 3D Zn anode enables preferential plating of Zn in the porous texture with suppressed dendrite growth, as confirmed by ex situ scanning electron microscopy and finite element analysis. The cycle life of the 3D Zn anode is sustained over 930 and 1500 h at 4.0 mA cm−2-2.0 mAh cm−2 and 1.0 mA cm−2-1.0 mAh cm−2, respectively. Furthermore, the assembled 3D Zn and α-MnO2 full batteries demonstrate a prolonged cycle life of 3000 cycles with improved rate performance. The etching strategy using non-aqueous organic acid paves a new way to fabricate 3D metal anodes for Zn and other metal anode batteries.
  • Evaluation of Detailed Reaction Models for the Modeling of Double Cellular Structures in Gaseous Nitromethane Detonation

    Chi, Dunstan Y.; Chatelain, Karl P.; Lacoste, Deanna (American Institute of Aeronautics and Astronautics, 2022-01-03) [Conference Paper]
  • Large eddy simulation of multi-regime burner: a reaction mechanism sensitivity analysis

    Angelilli, Lorenzo; Ciottoli, Pietro Paolo; Hernandez Perez, Francisco; Valorani, Mauro; Im, Hong G.; Malpica Galassi, Riccardo (American Institute of Aeronautics and Astronautics, 2022-01-03) [Conference Paper]
    High Reynolds number jets and mixture inhomogeneities enhance the presence of local reaction zones at different combustion regimes. From a modeling perspective, the multi-regime process requires ad-hoc models to be accurately described. In this work, highly resolved large eddy simulations of the Darmstadt multi-regime burner, which spans regimes from a fully non-premixed flame in the core jet region to an outer premixed flame as well as local extinction and re-ignition, are conducted using the eddy dissipation concept. Three different reaction mechanisms for methane are considered to study the effects of the kinetics model on the solution, including the detailed GRI Mech 3.0 and two reduced ones. The averages and fluctuations of the main scalars are compared against experimental data, and the mixing lines and conditional averages in the mixture fraction-progress variable space are also contrasted. The results highlight that a detailed description of chemical kinetics leads to a shrinkage of the predicted non-premixed flame and improves the prediction of the carbon monoxide mass fraction, when compared to the predictions obtained with the reduced chemistry models.
  • Uncertainty Quantification and Sensitivity Analysis for In-plane Thermo-mechanical Properties of 3-D Textile Composites

    Nasution, Muhammad Ridlo Erdata; Palar, Pramudita S.; Hadi, Bambang K.; Widagdo, Djarot; Zuhal, Lavi; Yudhanto, Arief (American Institute of Aeronautics and Astronautics, 2022-01-03) [Conference Paper]
    In this paper, uncertainty quantification and sensitivity analysis are performed for investigating the equivalent in-plane thermo-mechanical properties of 3-D orthogonal interlock composites. The composite properties are calculated based on the asymptotic expansion homogenization method omitting out-of-plane periodicity. The analysis herein employs 17 independent properties of constituents as inputs whereby six homogenized properties of composites become the quantity of interests (QOIs). Polynomial chaos expansion (PCE) is used to quantify the output uncertainty and the variance-based sensitivity indices. Two cases are investigated to understand the effects of material variation of constituents on each output of interest. The results show that the PCE model is highly accurate in quantifying the statistical outputs. Furthermore, acceptable accuracy for all QOIs is obtained by 100 sampling points. It is also found that material selection of constituents will determine the importance of input parameters in the calculation of QOIs.
  • Effect of O2/CO2ratio on stability and near field structure of oxyfuel jet diffusion flames at atmospheric pressure.

    Bukar, Muhammad; Basnet, Suman; Kim, Taesung; Magnotti, Gaetano (American Institute of Aeronautics and Astronautics, 2022-01-03) [Conference Paper]
    This paper presents an experimental study on the stability and structure of non-premixed CO2 diluted oxyfuel jet flames. DSLR imaging and OH Planar Laser-Induced Fluorescence (PLIF) were used to investigate the nearfield structure of a series of methane jet flames. Three oxidizer compositions (O2/CO2 ratios of 50/50, 40/60, and 32/68) were considered for a fixed co-flow velocity of 0.35 m/s. The PLIF Images were post-processed using MATLAB to obtain OH layer thickness, flame attachment height, and radius. Results show that increasing the CO2 level in the co-flow leads to a reduction in the OH layer thickness and sooting propensity. Both attachment radius and height were found to increase with increased CO2 content in the oxidizer. Furthermore, it was also observed that the flame attachment radius decreased as jet velocity increased while the flame attachment height tended to increase with higher jet velocity.

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