Assembling Hollow Carbon Sphere-Graphene Polylithic Aerogels for Thermoelectric Cells

Aerogels are highly porous bulk materials assembled chemically or physically with various nanoscale building blocks and thus hold promise for numerous applications including energy storage and conversion. Assembling of hollow or porous particles with the diameter larger than 100 nm into hierarchically porous aerogels is efficient but challenging for achieving a high specific surface of aerogel. In this regard, submicron-sized carbon spheres with hollow cores and microporous shells are assembled into bulk aerogels, for the first time, in the presence of two-dimensional graphene sheets as special cross-linkers. The resulting bead-to-sheet polylithic aerogels show ultra-low density (51–67 mg cm−3), high conductivity (263–695 S m−1) and high specific surface area (569–609 m2 g−1). An application of thermocells is demonstrated with maximum output power of 1.05 W m−2 and maximum energy conversion efficiency of 1.4% relative to Carnot engine, outperforming the current simple U-shaped thermocells reported elsewhere

Effect of Twice Hole Expansion on Fatigue Property of Ti1023 Alloy

The property of the surface layer of twice hole expansion Ti1023 alloy was analyzed by TEM, X-ray and roughness tester, and the strengthen mechanism of the bushing hole expansion was discussed. The results indicate that the roughness(Ra1.722→0.349 μm), hardness(Hv32→38) and residual stress distribution of the hole are improved by twice hole expansion techniques,and the fretting wear fatigue(fatigue limits 385→619MPa) of Ti1023 alloy is improved

Assembling graphene aerogel hollow fibres for solar steam generation

Solar vapor generation, a cost-effective way to harvest solar energy for purifying polluted or saline water, has attracted great attention in recent years. However, during the harsh environment (e.g. high-salinity brine), challenges still remain in limited water evaporation, complicated/compromised systems between water transport, evapor area and salt accumulation. Herein, graphene aerogel hollow fibers (GAHF) are developed and assembled into a solar steam generator which demonstrates exceptionally high efficiency for water evaporation and salt rejection under sun irradiation. Inspired from the capillary water transportation system in trees, the mesophase-ordered GAHFs are spun from their liquid crystalline suspension, and subsequently assembled into a roll of unidirectionally aligned bundles and then embedded in a transparent polydimethylsiloxane (PDMS) matrix. The synergistic effects between GAHFs, serving as 1D-confining micro-channels for water transport and broadband solar absorbers, and PDMS matrix, as an light refractor and “canyons”-like evaporation area, improve the water flow and absorption of solar energy and maximize the evaporation surface area. As a result, the GAHF arrays expedite remarkable transpiration, achieving continuous steam generation (∼3.29 kg m−2 h−1) and outstanding salt-rejection performance for high-salinity brine (e.g. saturated solution) desalination. This GAHF based solar steam generation system provides a facile and high-performance device for self-generating seawater desalination

Improving the Sound Absorption Capacity of Wood by Microwave Treatment

Microwave treatment (MW) was used to improve the sound absorption capacity of Pinus sylvestris var. mongolica wood. The effects of the processing parameters such as MW intensity, processing time, and board thickness on the sound absorption of treated wood were investigated. Microstructure changes of the wood after microwave treatment were observed using scanning electron microscopy (SEM) and mercury intrusion porosimetry (MIP). It was found that the microwave treatment significantly enhanced the sound absorption capacity of the wood in the middle frequencies. The optimum microwave treatment parameters for Pinus sylvestris var. mongolica wood to achieve an improved permeability are: MW intensity of 18 Kw, board thickness of 30 mm, and processing time of 80 s. The maximum sound absorption coefficient of treated wood was 0.51. Micro-voids were formed in treated wood due to the destruction of the pit membranes, the wood ray cells, as well as the damage in the intercellular layer of the longitudinal tracheids. The number of micro-voids ranging from 7427.6 nm to 400 um increased, resulting in the increase in the air permeability and in sound absorption by the treated wood

Interfacial Engineering for Highly Stable and Stretchable Electrodes Enabled by Printing/Writing Surface‐Embedded Silver and Its Selective Alloying with Liquid Metals

Abstract Even though intrinsically stretchable liquid metals (LMs) have been widely used in the stretchable electrodes for improving the stretchability, it is still challenging to achieve stable interfaces in these electrodes. A usual approach of adhering the LMs on a substrate is to modify the LMs with an organic surfactant, which is easily ruptured under a dynamic deformation. Herein, a surface‐embedded silver and its selective alloying of LMs are reported to address this problem. Typically, the surface‐embedding structure and the alloying interaction are both robust and stretchable, enabling the high interfacial stability during deformation (the ability to resist peeling, scratching, and sonication). And the cracked silver layer under tensile strains can be well bridged by LMs, enabling the good conducting stability during deformation (resistance change of 0.076 at 50% strain, 0.18 at 100% strain, and 0.4 at 200% strain). It is noted that this interfacial engineering can be facilely organized by directly printing or writing, which is convenient for preparing customized electrodes and circuits. At last, a light‐emitting diode array and a drone remote controller are assembled using the stretchable electrodes, showing their advantages in practical application

Geological features and exploration fields of tight oil in the Cenozoic of western Qaidam Basin, NW China

Using a large amount of drilling and experimental analysis data, this paper evaluates four potential fields of tight oil exploration in western Qaidam Basin from comprehensive analysis of geological conditions such as sedimentary environments, source rock evaluations, reservoir characteristics, and source-reservoir relationships. Influenced by continuous uplift of Tibet Plateau since Paleogene, the sedimentary environment of the western Qaidam Basin exibits three characteristics: (1) a paleo-topographic configuration consisted of inherited slopes, depressions and paleohighs; (2) frequent alternation of relative humid and arid paleoclimate; and (3) oscillation of salinity and level of the paleo-lake water. Preferential paleo-environment resulted in two sets of large-scale source rocks with high efficiency and two types of large-scale tight reservoir rocks (siliclastic and carbonate), deposited during the late Paleogene to early Neogene. The above source and reservoir rocks form favorable spatial relationships which can be classified into three categories: symbiotic, inter and lateral. Based on sedimentary environments and reservoir types, tight oil resource in western Qaidam Basin can be divided into four types, corresponding to four exploration fields: salty lacustrine carbonate tight oil, shallow lake beach-bar sandstone tight oil, delta-front-sandstone tight oil and deep lake gravity-flow-sandstone tight oil. The temporal and spatial distribution of tight oil has characteristics of layer concentration, strong regularity and large favorable area, in which the saline lacustrine carbonate and shallow lake beach-bar sandstone tight oil are the best exploration targets in the western Qaidam Basin. Key words: tight oil, geological features, exploration fields, Qaidam Basin, tight reservoi

Two Birds with One Stone: Using Indium Oxide Surficial Modification to Tune Inner Helmholtz Plane and Regulate Nucleation for Dendrite-free Lithium Anode

Lithium metal has been considered as the most promising anode material due to its distinguished specific capacity of 3860\ua0mAh g–1 and the lowest reduction potential of -3.04\ua0V versus the Standard Hydrogen Electrode. However, the practicalization of Li-metal batteries (LMBs) is still challenged by the dendritic growth of Li during cycling, which is governed by the surface properties of the electrodepositing substrate. Herein, a surface modification with indium oxide on the copper current collector via magnetron sputtering, which can be spontaneously lithiated to form a composite of lithium indium oxide and Li-In alloy, is proposed. Thus, the growth of Li dendrites is effectively suppressed via regulating the inner Helmholtz plane modified with LiInO2 to foster the desolvation of Li-ion and induce the nucleation of Li-metal in two-dimensions through electro-crystallization with Li-In alloy. Using the In2O3 modification, the Li-metal anode exhibits outstanding cyclic stability, and LMBs with lithium cobalt oxide cathode present excellent capacity retention (above 80% over 600 cycles). Enlightening, the scalable magnetron sputtering method reported here paves a novel way to accelerate the practical application of the Li anode in LMBs to pursue higher energy density

Development, sand control mechanism and hydrocarbon accumulation of beach-bar sandstone in a saline lake basin: A case from the Neogene of southwestern Qaidam Basin, NW China

Based on the data of field outcrops, drilling cores, casting thin sections, well logging interpretation, oil/gas shows during drilling, and oil/gas testing results, and combined with modern salt-lake sediments in the Qinghai Lake, the Neogene saline lake beach-bars in southwestern Qaidam Basin are studied from the perspective of sedimentary characteristics, development patterns, sand control factors, and hydrocarbon accumulation characteristics. Beach-bar sand bodies are widely developed in the Neogene saline lake basin, and they are lithologically fine sandstone and siltstone, with wavy bedding, low-angle cross bedding, and lenticular-vein bedding. In view of spatial-temporal distribution, the beach-bar sand bodies are stacked in multiple stages vertically, migratory laterally, and extensive and continuous in NW−SE trending pattern in the plane. The stacking area of the Neogene beach-bar sandstone is predicted to be 3 000 km2. The water salinity affects the sedimentation rate and offshore distance of beach-bar sandstone, and the debris input from the source area affects the scale and enrichment of beach-bar sandstone. The ancient landform controls the morphology and stacking style of beach-bar sandstone, and the northwest monsoon driving effect controls the long-axis extension direction of beach-bar sandstone. The beach-bars have a reservoir-forming feature of “one reservoir in one sand body”, with thick beach-bar sand bodies controlling the effective reservoir distribution and oil-source faults controlling the oil/gas migration and accumulation direction. Three favorable exploration target zones in Zhahaquan, Yingdong−eastern Wunan and Huatugou areas are proposed based on the analysis of reservoir-forming elements