Evolution of hydrothermal explosions at Rehai geothermal field, Tengchong volcanic region, China

During the period 1993–2003 over 20 hydrothermal eruptions occurred at Rehai geothermal field, in Tengchong volcanic region, Yunnan Province, southwestern China. Initially, the explosions occurred on the bed of the Zaotang River, and later along a NW–SE striking fault cross-cutting the river. The explosion activity intensified with time. The free gas samples collected from springs created by the explosions show ³He/⁴He ratios of 1.17, 2.22 and 4.05 Ra (Ra = 1.4 × 10⁻⁶) for the three distinguishable stages of ever-increasing magnitude of the explosions, respectively. Data on helium isotopes and gas chemistry indicate that the source of the gases feeding the explosions has progressively shifted from shallower to greater depth. Following this trend, larger hydrothermal explosions will probably occur in the future, so that this hazard must be taken into serious consideration.     

连续式超临界水中煤/CMC催化气化制氢

在向水煤浆中添加CMC（羧甲基纤维素钠），成功实现水煤浆高压均匀输送基础上，对超临界水中煤／CMC催化气化制氢性能进行了进一步研究。结果表明：在压力20～25MPa、停留时间15～30s、NaOH添加量0．1％、反应器外壁温650℃条件下，超临界水中煤/CMC催化气化制氢气体产物中H2摩尔含量远比常规气化高，主要气体产物是H2、CO2和CH4。增加物料中CMC的含量、升高压力均有利于提高气体产物中心的产量，延长停留时间虽有利于物料气化但不利于氢气的制取。     

客车发动机在中国的现状和发展趋势

结合我国现有国情,论述客车用发动机:燃油车、混合动力车、电动车、燃料电池和氢燃料车的现状和发展趋势,着重探讨了CNG/LNG车在我国的现状和发展趋势,并对各项动力进行综合比较分析。     

A highly efficient nanostructured quinary photocatalyst for hydrogen production

Semiconductor photocatalysts play a crucial role when it comes to environmental issues such as global warming, pollutant degradation, fuel shortage, and energy crisis. In this paper, three nanostructured compound (3‐, 4‐, and 5‐component) semiconductor materials were synthesized through a facile one‐pot hydrothermal method, and were applied as alloy photocatalysts to generate hydrogen fuel via a water photo‐splitting process. Nitrogen adsorption–desorption isotherms revealed that the synthesized materials were all mesoporous and the highest surface area was witnessed for Ag‐doped quinary photocatalyst, viz. Cd_0.1Zn_0.87Sn_0.01Ag_0.01S (CZTSS). This heterogeneous photocatalyst exhibited a maximum performance in evolving hydrogen gas. The superiority of CZTSS was justified in terms of its greater surface area, higher conduction band and its silver plasmon resonance, enhancing the light absorption at long wavelengths. Field emission scanning electron microscopy revealed a spectacular nanostructure for this photocatalyst that was comprised of nanoparticles, platelets, and microspheres attached together. Energy dispersive X‐ray (EDX) analyses of the CZTSS also proved the synthesis of the quinary photocatalyst, having different compositions in distinct zones. Copyright © 2014 John Wiley & Sons, Ltd.     

Power generation characteristics of a sandwich‐type self‐heating thermoelectric generator with spatially varying embedded heat source

Power generation characteristics of a sandwich‐type thermoelectric generator in which the heat source is embedded into thermoelectric elements are investigated. Our previous work on a similar concept only considered a uniform heat source distribution inside thermoelectric elements. In this work, the effect of the spatial distribution of a heat source is examined. In particular, the effect of the concentration of heat source near the one end, that is, the hot end, is intensively studied as a potential means of improving the efficiency of the device. Although the effects of heat source concentration in impractical cases without heat transfer limitations on the cold side remain ambiguous, it become clear that heat source concentration indeed has positive effects in more realistic cases with finite heat transfer coefficients imposed on the cold side. Because of the relatively low efficiency of typical thermoelectric generation, a significant amount of heat must be dissipated from the cold end of the thermoelectric element. Greater heat source concentration near the hot end leads to more effective utilization of available heat source, reduces the amount of heat rejected at the cold end, and lowers the hot end temperature of the thermoelectric element. Overall, it is suggested that heat source concentration can be used as a method to achieve more efficient operation and better structural integrity of the system. Copyright © 2015 John Wiley & Sons, Ltd.     

Development of a Highly Selective,Sensitive, and Fast Response Upconversion Luminescent Platform for Hydrogen Sulfide Detection

Hydrogen sulfide (H₂S) has been recognized as one of most important gaseous signaling molecules mediated by a variety of physiological and pathological processes. Yet, its functions remain largely elusive due to the lack of potent monitoring methods. Hereby this issue is addressed with a powerful new platform—dye‐assembled upconversion nanoparticles (UCNPs). A series of chromophores with different absorption bands and fast responses towards H₂S is combined with UCNPs and results in a library of H₂S sensors with responsive emission signals ranging from the visible to the near‐infrared (NIR) region. These nanoprobes demonstrate highly selective and rapid responses to H₂S in vitro and in cells. Furthermore, H₂S levels in blood can be detected using the developed nanoprobes. Hence the reported H₂S sensing platform can serve as a powerful diagnostic tool to research H₂S functions and to investigate H₂S‐related diseases.     

氢化非晶硅薄膜H含量控制研究进展

氢化非晶硅薄膜(a-Si∶H)是目前重要的光敏材料,而薄膜中的H含量及组态对薄膜的稳定性有着极其重要的影响。介绍了H对薄膜稳定性影响的原理,提出了控制薄膜中的H含量的必要性。分析了H在H稀释硅烷法制备氢化非晶硅中的作用,论述了制备工艺中衬底温度、H稀释比、气体压强等对薄膜H含量的影响及其机理,并对用不同方法控制H含量的优缺点进行了比较,分析了通过以上三种方法控制薄膜H含量的局限性。探寻了控制薄膜H含量的新方法,并对该领域的发展方向进行了展望。     

TiC/n型4H-SiC欧姆接触的低温退火研究

利用电子回旋共振(ECR)氢等离子体处理n型4H-SiC(0.5～1.5×1019cm-3)表面,采用溅射法制备碳化钛(TiC)电极,并在低温(<800℃)条件下退火。直线传输线模型(TLM)测试结果表明,TiC电极无需退火即可与SiC形成欧姆接触,采用ECR氢等离子体处理能明显降低比接触电阻,并在600℃退火时获得了最小的比接触电阻2.45×10-6Ω.cm2;当退火温度超过600℃时,欧姆接触性能开始退化,但是比接触电阻仍然低于未经氢等离子体处理的样品,说明ECR氢等离子体处理对防止高温欧姆接触性能劣化仍有明显的效果。利用X射线衍射(XRD)分析了不同退火温度下TiC/SiC界面的物相组成,揭示了电学特性与微观结构的关系。     

Nanoporous Surface High-Entropy Alloys as Highly Efficient Multisite Electrocatalysts for Nonacidic Hydrogen Evolution Reaction

Electrocatalytic hydrogen evolution in alkaline and neutral media offers the possibility of adopting platinum-free electrocatalysts for large-scale electrochemical production of pure hydrogen fuel, but most state-of-the-art electrocatalytic materials based on nonprecious transition metals operate at high overpotentials. Here, a monolithic nanoporous multielemental CuAlNiMoFe electrode with electroactive high-entropy CuNiMoFe surface is reported to hold great promise as cost-effective electrocatalyst for hydrogen evolution reaction (HER) in alkaline and neutral media. By virtue of a surface high-entropy alloy composed of dissimilar Cu, Ni, Mo, and Fe metals offering bifunctional electrocatalytic sites with enhanced kinetics for water dissociation and adsorption/desorption of reactive hydrogen intermediates, and hierarchical nanoporous Cu scaffold facilitating electron transfer/mass transport, the nanoporous CuAlNiMoFe electrode exhibits superior nonacidic HER electrocatalysis. It only takes overpotentials as low as ≈240 and ≈183 mV to reach current densities of ≈1840 and ≈100 mA cm⁻² in 1 m  KOH and pH 7 buffer electrolytes, respectively; ≈46- and ≈14-fold higher than those of ternary CuAlNi electrode with bimetallic Cu–Ni surface alloy. The outstanding electrocatalytic properties make nonprecious multielemental alloys attractive candidates as high-performance nonacidic HER electrocatalytic electrodes in water electrolysis.     

Wood-Inspired Binder Enabled Vertical 3D Printing of g-C3N4/CNT Arrays for Highly Efficient Photoelectrochemical Hydrogen Evolution

2D nanomaterials are very attractive for photoelectrochemical applications due to their ultra-thin structure, excellent physicochemical properties of large surface-area-to-volume ratios, and the resulting abundant active sites and high charge transport capacity. However, the application of commonly used 2D nanomaterials with disordered-stacking is always limited by high photoelectrode tortuosity, few surface-active sites, and low mass transfer efficiency. Herein, inspired by wood structures, a vertical 3D printing strategy is developed to rapidly build vertically aligned and hierarchically porous graphitic carbon nitride/carbon nanotube (g-C₃N₄/CNT) arrays by using lignin as a binder for efficient photoelectrochemical hydrogen evolution. Arising from the directional electron transport and multiple light scattering in the out-of-plane aligned and porous architecture, the resulting g-C₃N₄/CNT arrays display an outstanding hydrogen evolution performance, with the hydrogen yield up to 4.36 µmol (cm⁻² h⁻¹) at a bias of −0.5 V versus RHE, 12.7 and 41.6 times higher than traditional thick g-C₃N₄/CNT and g-C₃N₄ films, respectively. Moreover, this 3D printed structure can overcome the agglomeration problem of the commonly used g-C₃N₄ with powder configuration and shows desirable recyclability and stability. This facile and scalable vertical 3D printing strategy will open a new avenue to highly enhance the photoelectrochemical performance of 2D nanomaterials for sustainably production of clean energy.