Abstract
The operating principle of conventional water electrolysis using heterogenous catalysts has been primarily focused on the unidirectional charge transfer within the heterostructure. Herein, ...multidirectional charge transfer concept has been adopted within heterostructured catalysts to develop an efficient and robust bifunctional water electrolysis catalyst, which comprises perovskite oxides (La
0.5
Sr
0.5
CoO
3–
δ
, LSC) and potassium ion-bonded MoSe
2
(K-MoSe
2
). The complementary charge transfer from LSC and K to MoSe
2
endows MoSe
2
with the electron-rich surface and increased electrical conductivity, which improves the hydrogen evolution reaction (HER) kinetics. Excellent oxygen evolution reaction (OER) kinetics of LSC/K-MoSe
2
is also achieved, surpassing that of the noble metal (IrO
2
), attributed to the enhanced adsorption capability of surface-based oxygen intermediates of the heterostructure. Consequently, the water electrolysis efficiency of LSC/K-MoSe
2
exceeds the performance of the state-of-the-art Pt/C||IrO
2
couple. Furthermore, LSC/K-MoSe
2
exhibits remarkable chronopotentiometric stability over 2,500 h under a high current density of 100 mA cm
−2
.
This feature article presents a short review of the recent developments in the synthesis of conjugated polyelectrolytes (CPEs) along with their applications in organic optoelectronic devices with ...particular focus on the molecular structures of CPEs with ionic functionality, synthetic approaches, and their utilization as an interfacial layer. The orthogonal solubility of the CPEs allows the simple preparation of multilayer organic devices by solution casting on top of a nonpolar organic photoactive layer without disturbing the interfaces, showing their effectiveness in tuning the electronic structures at the interfaces for improving the charge carrier transport and resulting device properties. These achievements highlight the dynamic nature of CPEs and their applicability to a wide range of optoelectronic devices.
Display omitted
Thiophene- and thienothiophene-based donor–acceptor (D–A) type semicrystalline copolymers with different backbone curvatures, PTBT14 and PTTBT14, were designed and synthesized. Both the polymers ...exhibit a nearly planar structure via noncovalent S···O and C–H···N attractive interactions, etc., in the polymer chain. PTTBT14 is linear, whereas PTBT14 is curved owing to ∼160° bond angle of the thiophene linkage. PTTBT14 showed the higher degree of interchain ordering with edge-on orientation, resulting in efficient charge transport (0.26 cm2 V–1 s–1 for PTTBT14 compared to 0.02 cm2 V–1 s–1 for PTBT14) in PFETs with remarkable morphological stability and no deterioration in device properties at temperatures up to 250 °C. On the other hand, the curved shape of PTBT14 attributed to its improved photovoltaic properties with a power conversion efficiency of 5.56%. The linear PTTBT14 showed much stronger self-interactions with negligible morphological changes and little miscibility with PC61BM, showing the poor photovoltaic characteristics.
The percentage contribution of trans-boundary mercury (Hg) from China at different locations in South Korea was estimated from Hg anthropogenic emission distributions using the Hg dispersion model, ...CMAQ-Hg. This investigation quantifies the trans-boundary Hg emissions as contribution ratios. In addition, the long-range transportation frequency is also calculated, to verify inflow cases from China. The seasonal distribution of the Hg contribution ratio was found to be highest in winter (40%), followed by fall (16%). Seasonal observations of Hg inflow frequencies were estimated as 40%, 25%, 21%, and 4% in winter, fall, summer, and spring, respectively, at the same location. Such results would be produced by the wind generally blowing from the west and north-west with a speed of 5.0m/s and 4.5m/s, respectively, during winter and fall, around the study area. This study made an effort to quantify the trans-boundary Hg transport and to plot Hg anthropogenic emissions distribution in the region.
Graphical abstract of quantification of trans-boundary Hg in the region Display omitted
•The trans-boundary Hg in Northeast Asian region was predicted by the CMAQ-Hg model using anthropogenic emission data.•Amount of trans-boundary Hg was quantified between the countries as first attempt.•Higher levels of trans-boundary Hg contribution from China to South Korea were recorded in winter and fall.•Long-range transportation frequency and inflow cases from China to Korea were estimated by using the CMAQ-Hg model
Four different kinds of photovoltaic polymers were synthesized by controlling the intrachain noncovalent coulomb interactions through the incorporation of alkoxy- or alkylthio-substituted phenylene, ...4,7-di(furan-2-yl)benzothiadiazole, and 4,7-di(thiophen-2-yl)benzothiadiazole as a building block. Fine modulation of the interplay of dipole–dipole, H-bond, and chalcogen–chalcogen interactions (O···S, O···H, S···S, S···F, etc.) along the polymeric backbone influenced the chain planarity, interchain organization, film morphology, and electrical and photovoltaic properties significantly. By replacing the alkoxy substituents with alkylthio groups, the torsional angle increased (136–168°) due to the absence of an O···S attractive coulomb interaction (and/or increased S···S steric hindrance), enhancing the amorphous nature with hindered interchain packing. The alkoxy-substituted polymers exhibited nanofibrillar structures, showing strong interlamellar scattering peaks up to (300) with tight face-on π–π stacking in grazing incidence X-ray scattering. The measured carrier mobility of the alkoxy-containing polymers was 1–2 orders of magnitude higher than that of the alkylthio-containing polymers. The incident-light-intensity-dependent photovoltaic characteristics clearly suggested efficient charge generation/extraction with less charge recombination for the alkoxy-containing semicrystalline polymers. The resulting photovoltaic energy conversion efficiency of the PPDT2FBT, PPDF2FBT, PPsDF2FBT, and PPsDT2FBT blended devices with PC70BM was measured to be 8.28%, 5.63%, 5.12%, and 0.55%, respectively. This study suggests an important molecular design guideline for the further optimization of photovoltaic polymers and devices by finely controlling the interplay of the weak noncovalent coulomb interactions.
A
bstract
We first point out that the Laia-Tong model realizes the Lieb lattice in the holographic setup. It generates a flat band of sharp particle spectrum together with a Dirac band of unparticle ...spectrum. We provided an understanding why the Laia-Tong model’s boundary condition generate a flat band and compared it with the mechanism of “compact localized orbits” in the lattice models to provide a physical reason why Lieb and Laia-Tong model should be identified based on the similarity in the flat band generation mechanism. We then construct a model which opens a gap to the Dirac band so that one can realize a well-separated flat band. We then study the phase transition between the gapped and gapless phases analytically. We also made methodological progress to find a few other possible quantizations and we express the Green functions in any quantization in terms of that in the standard quantization. Finally we carried out the problem of back reaction to show that the qualitative feature remains the same.
ABC-stacked multilayer graphene in holography Seo, Jeong-Won; Yuk, Taewon; Han, Young-Kwon ...
The journal of high energy physics,
11/2022, Letnik:
2022, Številka:
11
Journal Article
Recenzirano
Odprti dostop
A
bstract
A flat band can be studied an infinitely strong coupling, realized in a simple system. Therefore, its holographic realization should be interesting. Laia and Tong gave a realization of the ...flat band over the entire momentum region by introducing a particular boundary term. Here, we give a model with a flat band over a finite region of momentum space using a bulk interaction term instead of the boundary term. We find that the spectrum of our model is precisely analogous to that of the ABC stacked multilayer graphene. In the presence of the chemical potential, the flat band is bent in our holographic model, which is very close to the band deformation due to the spin-orbit
•p-Dinitrobenzene is proposed for p-xylene separation solvent.•Molecular simulation is applied for VLE computation.•99.1% p-xylene is recovered at 99.6% purity.•Investment and utility costs are ...comparable to Parex process.
Though p-xylene derived from naphtha reformate is in high demand as a raw material in the production of polyesters and polyethylene terephthalates, its separation from the FCC reformate is not easy due to close boiling points among the components in the reformate. When a proper solvent for the p-xylene separation is available, an extractive distillation can be applied in the separation. Currently the separation utilizes an adsorption process requiring a large amount of costly adsorbent and a desorption process followed by distillation. In the proposed extractive distillation here, p-dinitrobenzene has been utilized to improve the separation of p-xylene from its ethylbenzene mixture. The VLE data of the ternary mixture estimated with the UNIFAC were compared to those computed from molecular simulation to show their reliability. An extractive distillation and solvent recovery were applied to obtain 99.6% purity p-xylene with 99.1% recovery. The economics of the proposed process demonstrates its comparability to the existing Parex process.
We investigate the influence of a matching load resistance on frequency responses of a lumped-electro-absorption modulator-integrated lasers (EMLs) whose modulation band-widths are extended by LC ...resonance effect. An equivalent circuit modeling is performed to determine the optimal values of a matching load resistance enabling 112-Gbaud PAM4 operation for a lumped-EML chip with an electro-absorption modulator (EAM) length of 150 um. To verify the simulation results, we package a lumped-EML submodule and measure its high-frequency charac-teristics. Then, we experimentally demonstrate that the 3-dB bandwidth of the lumped-EML submodule can be enhanced to 55 GHz and beyond by optimizing the matching load resistance value as well as lengths of the bondwires, although the EAM length is as long as 150 um. The fabricated lumped-EML submodule exhibits clear optical eye patterns under 112-Gbaud PAM4 operation.
To achieve carbon neutrality by 2050, Korea has been expanding its investment in renewal energy distribution and technology development. However, with this rapid expansion of renewable energy, public ...concern about it has grown. This study developed and used a big data analysis-based procedure to analyze the questions registered on Naver, the largest portal site in Korea, from 2008 to 2020 to identify public concern over renewable energy. The big data analysis-based procedure consisted of two steps. The first was a frequency analysis to identify the most frequently registered words. The second was to classify questions using term frequency-inverse document frequency (TF-IDF) weight and cosine similarity based on word2vec. The analysis revealed the most frequently registered words related to renewable energy, such as “solar power,” “power generation,” “energy,” and “wind power.” It also revealed the most frequently registered questions, such as those related to solar panel installation, renewable energy generation methods, and certificates. To continue expanding renewable energy, it is becoming increasingly important to understand the public’s concerns and create a method to resolve their objections to renewable energy. It is expected that the procedure in this study may provide relevant insight for the method.
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