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Monolayer Metal Phthalocyanine for Efficient Electrocatalysis
No full textDepartment of Chemistryclos
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No full textAs environmental and sustainable energy issues emerge, interest in renewable electricity, improving efficiency, and energy storage systems have grown based on carbon-supported catalysts. However, there are still many challenges to preparing catalysts to realize in a large area. Herein, a method has been devised using mass-producible conventional carbon fiber synthesis to manufacture the fabric electrocatalyst (FEC). In addition, the internal structure of fibers intertwined with metal has been investigated to elucidate the relationship between catalytic activity and structure
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Challenges of Near Critical-Fixed Source Monte Carlo Simulations of CANDU-6 Reactor: Bundle Power Tally Bias and Error Autocorrelation from Exceeding Random-Number Stride
No full textThis study quantifies the effect of exceeding random number stride (RN) in Monte Carlo simulations of subcritical, multiplying systems. We observed all fixed-neutron-source simulations of an accelerator-driven photoneutron source (ADS) coupled to a CANDU-6 full core model in different subcritical states readily exceeded the default RN stride up to a factor of 104. Bundle tally results from stride exceedance cases are biased by up to 4% relative to clean reference results using extended stride (no stride exceedance) due to correlated particle histories when the stride is exceeded, and the exact same RNs are used in the thermal diffusion random walk of the neutrons through the optically thick and repeating heavy water lattice. Error analysis of local bundle tallies clearly shows bias indicated by both a statistically significant number of relative errors exceeding three-sigma statistical uncertainty intervals of the reference solutions and strong autocorrelation of the relative errors correlated to the spatial relationship of bundle powers in the 3D core. Closer inspection on bundle-power variance of simulation where all histories exceeded the stride reveal there is no variance underestimation when stride exceedance occurs. This result is clearly contrary to the widely reported argument that Monte Carlo codes are insensitive to the stride exceedance and stride exceedance may cause underestimation of the variance solely based on the early study by Hendricks [1]. Monte Carlo practitioners should monitor RN usage statistics for problems where excessive RNs use may occur (i.e. subcritical multiplication, highly diffusing media, aggressive particle splitting, etc.) and reinvestigate the impact of stride exceedance in production radiation transport codes
Quantifying the Ground-State Hydrogen-Bond Formation of a Super-Photoacid by Inspecting Its Excited-State Dynamics
No full textThe identification and quantification of hydrogen (H)-bonded complexes form the cornerstone of reaction-mechanism analysis in ultrafast proton transfers. Traditionally, the Benesi-Hildebrand method has been employed to obtain the formation constants of H-bonded complexes, given that H-bonding additives induce an alteration in spectral features exclusively through H-bond formation. However, if the additive introduction impacts the bulk polarity of the solution, inducing a spectral shift, the spectroscopic method's accuracy in analyzing the H-bond formation becomes compromised. In this study, we scrutinize H-bond formation under the influence of an H-bond accepting solute in an aprotic solvent. This is achieved by quantifying the fractions of two concurrent pathways involved in the excited-state proton transfer (ESPT) of a super-photoacid: the ultrafast ESPT of an H-bonded complex vs. the diffusion-controlled ESPT of the free acid. Our method offers improved accuracy compared to conventional steady-state spectroscopic techniques, by directly quantifying the H-bonded complexes using the time-resolved spectroscopic method, thereby circumventing the aforementioned limitation
Prediction and Analysis of Radiated EMI From a Wafer-Level Package Based on IC Source Modeling
No full textThis article proposes a comprehensive analysis and prediction method for wafer-level radiated electromagnetic interference (EMI) based on integrated circuit (IC) source modeling. An IC and a simplified wafer-level package (WLP) with a redistribution layer (RDL) were designed and fabricated for the research. The IC that draws currents through the RDL is efficiently modeled as a Thevenin equivalent circuit in the frequency domain. The equivalent EMI source model can simply replace complex time-domain operations of the IC that cannot be easily implemented in a full-wave field solver. To simulate the radiated EMI from the wafer-level RDL, the EMI source model is incorporated into the full-wave solver. The proposed approach is validated by comparing the simulated fields using the EMI source model and the measured fields on the WLP. The tendency of the radiated fields shows a high correlation with the common-mode current flowing through the RDL. The IC source modeling approach enables the decomposition of EMI factors into an IC operation and WLP structure
Prussian Blue-Type Sodium-ion Conducting Solid Electrolytes for All Solid-State Batteries
No full textConventional solid electrolyte frameworks typically consist of anions such as sulphur, oxygen, chlorine, and others, leading to inherent limitations in their properties. Despite the emergence of sulphide, oxide, and halide-based solid electrolytes for all-solidstate batteries, their utilization is hampered by issues, including the evolution of H2S gas, the need for expensive elements, and poor contact. Here, we first introduce Prussian Blue analogue (PBA) open-framework structures as a solid electrolyte that demonstrates appreciable Na+ conductivity (> 10 (-2)mScm (-1)). We delve into the relationship between Na+ conductivity and the lattice parameter of N-coordinated transition metal, which is attributed to the reduced interaction between Na+ and the framework, corroborated by the distribution of relaxation times and density functional theory calculations. Among the five PBAs studied, Mn-PBA have exhibited the highest Na+ conductivity of 9.1x10(-2)mScm (-1). Feasibility tests have revealed that Mn-PBA have maintained a cycle retention of 95.1% after 80cycles at 30 degrees C and a C-rate of 0.2C. Our investigation into the underlying mechanisms that play a significant role in governing the conductivity and kinetics of these materials contributes valuable insights for the development of alternative strategies to realize all-solid-state batteries
Revealing CdSe Quantum Dots Plasmonics Confined in Au Nanotrenches by Thermoacoustic Spectroscopy
No full textIn this work, the influence of Au plasmonics on the thermoacoustic (TA) response of integrated thiol-linked CdSe quantum dot-Au nanotrench structures is demonstrated. The TA measurement technique uses a modulated light beam illuminating the sample placed into the air-filled cell and measures the temperature oscillation in the sample resulting from the light absorption. The intermittent heat generates an acoustic signal in the cell that is detected by a microphone. We observed an enhanced acoustic signal with increased light absorption. The enhancement is correlated with the plasmonic absorption by the Au grating layers. The signal is even more enhanced in two well-defined spectral bands peaking at about 400 and 490 nm due to CdSe QDs. The approach presented here can be extended in various fields employing light-to-heat conversion processes in hybrid metal???semiconductor nanomaterials and nanoplasmonic systems