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91.
Microorganisms play a vital role in understanding the ecological system. The motions of micororganisms are self‐propelled while the impact of thermophoresis and Brownian motion property of nanoparticle shows more challenges in biotechnological and medical applications. The present problem is based on the understanding of double‐dispensed bioconvection for a Casson nanofluid flow over a stretching sheet. Suction phenomenon is introduced at the surface of the stretching sheet along with the convective boundary condition. The convection and movement of the microorganisms are assisted by an applied magnetic field, nonlinear thermal radiation, and first‐order chemical reaction. The governing equations are highly coupled and thus we used the spectral quasilinearization method to solve the governing equations. The study of the residual errors on the systemic parameters had given a confidence with the present results. The final outcomes are displayed through graphs and tables. The thermal dispersion coefficient shows a positive response in the temperature while a similar response is observed for the concentration with solutal dispersion coefficient. The response is reversible for the heat transfer rate at the surface with thermal dispersion coefficient. The density of the motile microorganism at the surface decreases with increase in the Casson number, thermal dispersion coefficient, and solute dispersion coefficient, while an opposite phenomenon was observed with increase in the density ratio of the motile microorganism. 相似文献
92.
《International Journal of Hydrogen Energy》2020,45(30):15063-15075
Electrochemical hydrogen evolution reaction (HER) via the splitting of water has required electrocatalysts with cost-effectiveness, environmentally friendliness, high catalytic activity, and superior stability to meet the hydrogen economy in future. In this context, we report the successful synthesis of self-standing mesoporous Ni2P–MoP2 nanorod arrays on nickel foam (Ni2P–MoP2 NRs/3D-NF) through an effective phosphidization of the corresponding NiMoO4 NRs/3D-NF. The as-synthesis Ni2P–MoP2 NRs/3D-NF, as an efficient HER electrocatalyst, exhibits small overpotential of 82.2 and 124.7 mV to reach current density of 10 and 50 mA cm−2, a low Tafel slope of 52.9 mV dec−1 and it retains its catalytic performance for at least 20 h in alkaline condition. Our work also offers a new strategy in designing and using transition metal phosphide-based 3D nanoarrays catalysts with enhanced catalytic efficiency for mass production of hydrogen fuels. 相似文献
93.
以碱式碳酸镍、碱式碳酸锌、碱式碳酸铜和水泥为原料制备水泥负载的Cu-Ni,Cu-Zn,Cu-Ni-Zn催化剂,考察了合成催化剂的甲醇裂解反应性能。结果表明:在常压、质量空速为3.39 h-1、温度为380~420 ℃的条件下,Cu-Ni/水泥催化剂作用下的甲醇转化率均在96%以上;Cu-Zn/水泥催化剂作用下的甲醇转化率较低,但对H2和CO选择性较高;Cu-Ni-Zn/水泥催化剂经1 600 h运转,甲醇转化率和产物分布变化不大,甲醇转化率基本维持在81%以上,(H2+CO)摩尔分数大于98%,说明Cu-Ni-Zn/水泥催化剂具有良好的高温稳定性。 相似文献
94.
95.
Jing Li Ping Liu Yan Qu Tingdi Liao Bin Xiang 《International Journal of Hydrogen Energy》2018,43(5):2601-2609
The number of exposed active sites in a catalyst plays a key role in determining its catalytic performance. However, the aggregation effect in nanostructured catalysts causes much less reactive sites exposed. In this paper, we report a novel structure of WSe2/rGO with highly exposed WSe2 active edge sites by uniformly imbedding the rGO between each WSe2 nanosheets. With the introduction of rGO, the electron transport property of the WSe2/rGO hybrid structure has also been enhanced. The structure and composition of the samples were investigated by the X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy and transmission electron microscopy. Our electrochemical characterizations confirm that the WSe2/rGO hybrid structure exhibits enhanced electrochemical catalytic performance with a Tafel slop of 85 mV/dec for HER, much smaller than that of the pure WSe2. 相似文献
96.
《Journal of the European Ceramic Society》2020,40(8):3348-3353
Large transduction coefficient () is difficult to obtain in piezoelectric ceramics because these two parameters show opposite trends with compositional modifications. Herein, the Pb(Zr0.53Ti0.47)O3 ceramic powders were calcinated under different temperatures (A:830 °C, B:860 °C, and C:890 °C), and then mixed together according to different weight ratios (1A:1B:1C, 1A:2B:1C, 1A:2B:3C and 3A:2B:1C) for ceramics preparation. Both d33 and g33 are improved successfully, and the transduction coefficient with the weight ratio of 1A:2B:3C reaches up to 17,500 × 10−15 m2/N, which is 60 % higher than that with the powders calcinated under 830 °C, and at least twice those of commercial PZT-4, PZT-5A and PZT-8 ceramics. The improved transduction coefficient is owing to the enhanced piezoelectric constant and spontaneous polarization resulted from the increased grain size, relative density and the fraction of tetragonal phase. These results indicate that this is a simple but effective way to tailor the transduction coefficient in piezoelectric ceramics. 相似文献
97.
Epoxy/polysufone (PSF) composites cured with 4,4'-diaminodiphenyl sulfone (DDS) and 4,4'-diaminodiphenyl methane (DDM) were fabricated, and the effect of dual curing reaction of diamines with epoxy on morphology, mechanical, and thermal performance was investigated. DSC results indicated that DDM was more reactive than DDS and the activation energy decreased with the rising of DDM content. Structures with small domain size at the early stage of phase separation were fixed by the fast epoxy-DDM reaction. When the DDM content was elevated to a high level, large dual structures were changed to fine bicontinuous structures, which was favorable to improve the mechanical property. The mechanical performance of epoxy composites was enhanced and the maximum values were achieved when the DDM/DDS ratio was located at 75/25 (PSF/DDS0.25-DDM0.75). The flexural and tensile strength relative to epoxy/DDM system were enhanced more than those relative to epoxy/DDS, while the increase in toughness was the opposite. TGA measurement showed that thermal stability of epoxy/PSF composites was improved because of the restricting effect of continuous PSF domains on thermal motion of epoxy. DMA analysis exhibited two relaxation peaks for PSF/DDS0.25-DDM0.75, which could be attributed to the formation of phase separated morphology and epoxy network with different cross-link density. 相似文献
98.
以KH560(3-缩水甘油基氧基丙基三甲氧基硅烷)和纳米SiO2颗粒复配作为扩链剂,采用“一步法”反应挤出增黏聚对苯二甲酸乙二醇酯(PET)。KH560和SiO2的添加量均为PET质量分数的2.5%时,增黏效果最好。并且在PET不干燥的情况下,KH560和SiO2复配也可增加PET的黏度,可用作PET的扩链剂和防水解剂。经透射电镜观察,发现SiO2在PET中的分散状况良好。用FTIR研究了KH560、SiO2、PET三者之间的反应机理。用TGA分析了SiO2的接枝率,发现接枝率高达72.0%。用DSC对PET/纳米SiO2复合材料的结晶行为进行了研究,并讨论了结晶行为对力学性能的影响。当KH560和SiO2的添加量均为PET质量分数的2.5%时,结晶度最低,综合力学性能最好。 相似文献
99.
《International Journal of Hydrogen Energy》2020,45(27):14028-14037
Intermetallic alloy ZrCo is believed to be a good substitution for uranium to store tritium. Nevertheless, disproportionation reaction often happens during the hydriding and dehydriding processes, and hydrogen storage property of ZrCo is therefore degraded. Alloying elements are often used to substitute Zr or Co in ZrCo to restrain disproportionation reaction. However, many experimental results do not agree with each other, and it lacks overall tendency for all transition metal elements. In this work, systematical ab initio calculations are performed to study more than 20 transition alloying elements to substitute Co and Zr in ZrCoH3 to study the anti-disproportionation effects. It is found that substitution of Co by transition metal elements on anti-disproportionation reaction is unconspicuous, and only Ni can enlarge Zr–H bond length and decrease the volume of 8e site, presenting anti-disproportionation effect, which qualitatively agrees with the previous experiments. In contrast, all transition alloying elements considered except Fe, Co, Ni, Ru, Rh, Pd, Os and Ir replacing Zr can both enlarge the length of Zr–H bond and decrease the volume of 8e site, and thus restrain the disproportionation effects. At last, two-dimensional charge density and density of states are calculated to analyze the underlying mico-mechanisms affecting the effects of transition alloying elements on anti-disproportionation reaction. 相似文献
100.
《International Journal of Hydrogen Energy》2020,45(20):11749-11760
To make SOFC high efficiency energy generation devices, thin ceramic films are proposed as their main components. The rate of the oxygen reduction reaction is relevant for the overall performance of the SOFC, hence a lot of attention is given to the cathodes and their interfaces. The airbrushed solution combustion (ASC) method was used to fabricate an LSM thin film on a dense YSZ substrate. A single phase LSM perovskite was obtained with very thin and interconnected porosity, and a small average grain size (55 nm). The nanostructured LSM thin film electrode showed a low total activation energy (1.27 eV) at high temperatures, but a high area specific resistance at 850°C (55 Ω.cm2). The activation energy for the dissociative adsorption and diffusion of oxygen was significantly low (1.27 eV), while the charge transfer and oxygen ion migration activation energy at the LSM/YSZ interface (1.28 eV) was closer to those usually reported. 相似文献