The current focus of research lies in the advancement of electrocatalysts based on phosphides, which exhibit exceptional features and robust stability in alkaline environments.
Abstract Nano and single‐atom catalysis open new possibilities of producing green hydrogen (H 2 ) by water electrolysis. However, for the hydrogen evolution reaction (HER) which occurs at a characteristic reaction rate proportional to the potential, the fast generation of H 2 nanobubbles at atomic‐scale interfaces often leads to the blockage of active sites. Herein, a nanoscale grade‐separation strategy is proposed to tackle mass‐transport problem by utilizing ordered three‐dimensional (3 d ) interconnected sub‐5 nm pores. The results reveal that 3 d criss‐crossing mesopores with grade separation allow efficient diffusion of H 2 bubbles along the interconnected channels. After the support of ultrafine ruthenium (Ru), the 3 d mesopores are on a superior level to two‐dimensional system at maximizing the catalyst performance and the obtained Ru catalyst outperforms most of the other HER catalysts. This work provides a potential route to fine‐tuning few‐nanometer mass transport during water electrolysis.
Attribute reduction of incomplete decision table is one of the important contents of Rough Set theory. The paper presents an attribute reduction algorithm of incomplete decision table based on information entropy, where the attribute reduction method based on information entropy is studied and analyzed. In the proposed method, the relative core of decision table is treated as the starting point. And then the concept of entropy is employed as heuristic information and conditions of reduction for seeking attribute reduction with a bottom-up approach. Finally, experimental results verify the feasibility and effectiveness of this method.
Electrochemical lithium insertion/extraction reaction in the β-LixV2O5 phase (0 < x ≤ 3) as the cathode material for rechargeable lithium batteries was examined. Of interest is the rigid 3D host lattice of the monoclinic tunnel-like β lithium bronze that shows desirable structural reversibility upon high Li uptakes (∼3 mol per formula unit), and a remarkable discharge capacity exceeding 330 mA h g−1 during 50 cycles were obtained at 10 mA g−1 in the 4.0/1.8 V potential range. Owing to the complicated ordering processes of crystallographic site occupancy, the pure Li-inserted β phase exhibits rather complex electrochemical properties. New Li diffusivity data within the entire concentration range were obtained by electrochemical impedance spectroscopy and galvanostatic intermittent titration. The slow diffusion kinetics at the deeply discharged state (x > 2.0) is mainly responsible for the large polarization during the process as well as a notable capacity drop (around 24% of the initial low-rate capacity) at a higher rate (50 mA g−1). Further, an abrupt decline in the kinetics of charge-transfer during 0.33 < x ≤ 1.0 is discovered, which results from the re-arrangement of the inserted Li+ among the various interstatial sites in the tunnel framework as lithiation proceeds.
Objectives To investigate the independent and interactive associations of physical activity (PA) and screen time (ST) with depression, anxiety and sleep quality among Chinese college students. Methods A cross-sectional study was conducted in Wuhan University, China from November to December 2011. The students reported their PA, ST and socio-economic characteristics using self-administered questionnaires. Sleep quality was measured by the Pittsburgh Sleep Quality Index (PSQI). Depression and anxiety were assessed using the Self-rating Depression Scale (SDS) and Self-rating Anxiety Scale (SAS), respectively. Multivariate logistic regression models were used to estimate the odds ratios (ORs) and 95% confidence intervals (CIs) of the independent and interactive relationships of PA and ST with depression, anxiety and sleep quality. Results A total of 1106 freshmen (471 females and 635 males) aged 18.9±0.9 years were included in the study. After adjustment for potential confounders, high PA and low ST were independently associated with significantly lower risks for poor sleep quality (OR: 0.48, 95% CI: 0.30–0.78) and depression (OR: 0.67, 95%CI: 0.44–0.89), respectively. An interactive inverse association was observed for combined effects of PA and low ST on depression (OR: 0.62, 95%CI: 0.40–0.92) and sleep quality (OR: 0.51, 95%CI: 0.27–0.91). No statistically significant associations were found between PA, ST and anxiety among the participants. Conclusions These findings suggest an independent and interactive relationship of high PA and low ST with significantly reduced prevalence of depressive problems and favorable sleep quality among Chinese college freshmen.
Emergency communication system is the most important communication mean in nuclear power plant because it relevant to emergency response. The research of safety requirements for emergency communication system in nuclear power plant is introduced in this paper. Based on the safety requirements and analysis, the design scheme of emergency communication system of nuclear power plant is developed by the design of architecture, layout and power supply. The design scheme of emergency communication system will be used in the new HPR1000 (Hua-long Pressurised Reactor) project, including UK HPR1000. It can also be used on the nuclear power plant of CPR1000 (Chinese Pressurised Reactor), ACPR1000 (Advanced Chinese Pressurised Reactor), EPR (European Pressurised Reactor) and AP1000 (Advanced Passive Pressurised Water Reactor).
Nanoscale solid superacid SO42–/ZrO2/WO3 is coupled into imidazole-hydroxyl-quaternary ammonium co-functionalized polybenzimidazole (PG112) to address the trade-off effect of membrane for large-scale flow battery application. Nanoscale SO42–/ZrO2/WO3 particles with high sulfonic groups are dispersed in membrane as redox-active ion barriers and proton carriers, which mitigate the electrolyte crossover and maintain high ion conductivity. The VO2+ permeability of the prepared membrane (7.86 × 10–10 cm2 s–1) is significantly lower than those of PG112 (3.93 × 10–9 cm2 s–1) and Nafion 212 (7.76 × 10–8 cm2 s–1) membranes. The vanadium flow battery with this membrane exhibits a longer self-discharge duration time of 231 h compared with Nafion 212 (35 h) and PG112 (88 h) membranes. High coulombic efficiencies of 97.5–99.2% at 40–120 mA cm–2 are obtained for the prepared membrane, which are higher than those for Nafion 212 (78.0–92.8%) and PG112 membranes (96.2–98.6%). Stable cycle performance and low retention capacity are also observed, suggesting the excellent chemical stability of the prepared membrane in vanadium flow battery operation. This work provides a prospective and applicable membrane to enhance the performance of flow battery.
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