Sputtered Ir–Ru based catalysts for oxygen evolution reaction: Study of iridium effect on stability

Magnetron sputtered low-loading iridium-ruthenium thin films are investigated as catalysts for the Oxygen Evolution Reaction at the anode of the Proton Exchange Membrane Water Electrolyzer. Electrochemical performance of 50 nm thin catalysts (Ir pure, Ir–Ru 1:1, Ir–Ru 1:3, Ru pure) is tested in a Rotating Disk Electrode. Corresponding Tafel slopes are measured before and after the CV-based procedure to compare the activity and stability of prepared compounds. Calculated activities prior to the procedure confirm higher activity of ruthenium-containing catalysts (Ru pure > Ir–Ru 1:3 > Ir–Ru 1:1 > Ir pure). However, after the procedure a higher activity and less degradation of Ir–Ru 1:3 is observed, compared to Ir–Ru 1:1, i.e. the sample with a higher amount of unstable ruthenium performs better. This contradicts the expected behavior of the catalyst. The comprehensive chemical and structural analysis unravels that the stability of Ir–Ru 1:3 sample is connected to RuO₂ chemical state and hcp structure. Obtained results are confirmed by measuring current densities in a single cell.     

Stabilized β-Bi2O3 nanoparticles from (BiO)4CO3(OH)2 precursor and their photocatalytic properties under blue light

Stabilized tetragonal Bi₂O₃ nanoparticles (β-Bi₂O₃) were obtained by annealing treatments of amorphous Bi-based precursors, obtained by chemical precipitations, at temperatures between 350 and 450?°C. The formation of the stabilized β-Bi₂O₃ phase was possible by using (BiO)₄CO₃(OH)₂ while other precursors such as amorphous bismuth carbonate ((BiO)₂CO₃) and amorphous basic bismuth nitrate (Bi₆O₆(OH)₂(NO₃)₄·2H₂O) led to the formation of the thermodynamically stable monoclinic α-Bi₂O₃ and Bi₅O₇NO₃ phases. The Bi-based precursors were prepared by the chemical precipitation method at room temperature in ethylenediamine-solvent varying the HNO₃/Bi³⁺ molar ratio (10, 26 and 56). The physicochemical properties of the three as-prepared amorphous precursors and the formed-after-calcination β-Bi₂O₃, α-Bi₂O₃ and Bi₅O₇NO₃ phases were analyzed by X-ray diffraction, scanning electron microscopy, thermogravimetry, X-ray photoelectron spectroscopy (XPS), FTIR analysis, diffuse reflectance spectroscopy and surface area by BET method. The photocatalytic activity of all annealed solids containing the β-Bi₂O₃ phase was tested in the photodegradation of the indigo carmine (IC) dye under specific blue light. A schematic diagram of the Bi₂O₃ phases obtained as a function of the annealing conditions and initial amorphous precursor is proposed and explained in terms of the amount of CO₃^2-, NO₃^- and amine (ENH₂²⁺ ? ENH⁺) ions present in each bismuth precursor.     

热稳定处理时间对TNM合金糊状区组织的影响

利用真空非自耗电弧炉制备了TNM(Ti-44Al-4Nb-1Mo-0.1B at.%)合金锭,研究其铸态组织形貌,并利用Bridgeman定向凝固装置对TNM合金进行热稳定处理实验,分析热稳定处理时间对合金定向凝固糊状区的影响。实验结果显示,其铸态组织是以(α₂+γ)片层团为主体,网络状B2相、细小的γ相及硼化物分布于片层团间的近片层组织。热稳定处理时,热稳定时间越长、TNM合金固/液界面越平整,界面前沿温度场和溶质场趋向均匀,但从减少坩埚对熔体的污染的角度考虑,热稳定处理时间不宜过长,30~60 min的热稳定时间即可提供平整的定向凝固启动界面。 热稳定处理影响着TNM合金固/液界面附近固液两相中Al元素的分布,进而影响硼化物的分布。     

Stability of perovskite materials and devices

Due to the excellent optoelectronic properties, organic–inorganic perovskites have drawn much attention and have been applied in different electronics with remarkable performance. However, the poor stability creates a massive barrier for the commercialization of perovskite electronic devices. In this review, we discuss intrinsic and extrinsic factors causing instabilities of perovskites and perovskite devices such as solar cells, liquid crystal displays (LCDs), light emitting diodes (LEDs), ionizing radiation detectors, transistors, memristors and sensors. We further review the stabilization approaches, including composition engineering, adoption of lower dimensional compositions, quantum dots, interface engineering, defects engineering and so on.     

Preparation and characterization of fully waste-based glass-ceramics from incineration fly ash,waste glass and coal fly ash

Municipal solid waste incineration (MSWI) fly ash (FA) is a typical hazardous waste due to its high contents of toxic heavy metals, and hence its disposal has attracted global concern. In this work, it was recycled into environmental-friendly CaO–Al₂O₃–SiO₂ system glass-ceramics via adding coal fly ash (CFA) and waste glass (WG). The effects of CaO/SiO₂ ratios and sintering temperatures on the crystalline phases, morphologies, mechanical and chemical properties, heavy metals leaching and potential ecological risks of glass-ceramics were investigated. The results showed that wollastonite (CaSiO₃), anorthite (CaAl₂Si₂O₈) and gehlenite (Ca₂Al₂SiO₇) were the dominant crystals in the glass-ceramics, which were not affected by CaO/SiO₂ ratio and sintering temperature. The compressive strength increased, while the Vickers hardness and microhardness decreased as increasing the sintering temperatures from 850 to 1050 °C, which reached their maximum values of 660.69 MPa, 6.14 GPa, and 7.43 GPa, respectively. However, the increase of CaO/SiO₂ ratio resulted into the reduction of the three mechanical parameters. As varying CaO/SiO₂ ratio from 0.48 to 0.86, the maximum compressive strength, Vickers hardness and microhardness were 611.80 MPa, 5.43 GPa, and 6.56 GPa, respectively. Besides, all the glass-ceramics exhibited high alkali resistance of >97%. The extremely low heavy metals leaching concentrations and low potential ecological risk of glass-ceramics further revealed its environmentally friendly property and potential application feasibility.     

220kV丽江变电所注浆加固地基失败原因探讨

由于注浆加固软土层是挤密、劈裂、渗透的复合过程,因而采用传统、单一的渗透注浆理论来计算与实际情况有较大的偏差.把软土体看作遵循Tresca屈服准则的理想弹塑体,同时结合浆液的柱状扩散情况,利用圆筒形扩张理论来计算浆液扩散半径和注浆压力.并以220kV丽江变电所注浆加固地基为例,分析其注浆失败的原因.     

Assessment of chromium biostabilization in contaminated soils using standard leaching and sequential extraction techniques

The iron reducing microorganism Desulfuromonas palmitatis was evaluated as potential biostabilization agent for the remediation of chromate contaminated soils. D. palmitatis were used for the treatment of soil samples artificially contaminated with Cr(VI) at two levels, i.e. 200 and 500 mg kg^− 1. The efficiency of the treatment was evaluated by applying several standard extraction techniques on the soil samples before and after treatment, such as the EN12457 standard leaching test, the US EPA 3060A alkaline digestion method and the BCR sequential extraction procedure. The water soluble chromium as evaluated with the EN leaching test, was found to decrease after the biostabilization treatment from 13 to less than 0.5 mg kg^− 1 and from 120 to 5.6 mg kg^− 1 for the soil samples contaminated with 200 and 500 mg Cr(VI) per kg soil respectively. The BCR sequential extraction scheme, although not providing accurate estimates about the initial chromium speciation in contaminated soils, proved to be a useful tool for monitoring the relative changes in element partitioning, as a consequence of the stabilization treatment. After bioreduction, the percentage of chromium retained in the two least soluble BCR fractions, i.e. the “oxidizable” and “residual” fractions, increased from 54 and 73% to more than 96% in both soils.     

寻找失落的遗传密码：历史风貌核心区空间修复性设计研究——天津市解放北路街区改造示例

随着越来越多的历史街区及建筑遭受到日益严重的破坏，如何有效地对这些街区进行保护，提出可操作性强的控制指标，已经成为历史街区保护所面临的新课题。本文以天津市解放北路历史风貌核心区为便，采用数理统计和参考控制相结合的方式，探求一种新的研究方法，期望通过这种研究方法寻找量化的参数、准确而又清晰地对这些街区风貌进行控制。     

Formation of metacinnabar by milling of liquid mercury and elemental sulfur for long term mercury storage

In this paper we present the results of the formation of black HgS (metacinnabar) from liquid mercury and elemental sulfur using the mechanical energy provided by a ball mill in different conditions. Metacinnabar formation was observed even after short milling times (15 min) and unreacted liquid mercury was no longer detected after 60 min of milling. The reaction mechanism was monitored with a scanning electron microscope. The impact and friction forces of milling on the Hg and S mixture resulted in the formation of metacinnabar by reducing the size of mercury drops, giving rise to microspheres, and lowering the surface tension to allow sulfur grains to become adhered at the reaction interface.After 60 min of milling, the metacinnabar formation reaction was observed to be more than 99.99% complete, yielding a Toxicity Characteristic Leaching Procedure value of 3.1 μg/L Hg. The reaction product thus complies with the limits of the most stringent Universal Treatment Standard requirements, which allow a maximum TCLP concentration of 25 μg/L.     

Effects of primary curing and subsequent disturbances on strength development of steel slag-treated marine clay

Steel slag-treated marine clay (SSTC) is a novel geomaterial used for recycling steel slag. This article reports the effects of the primary curing (the time delay between mixing and fill work) and the subsequent disturbances (the processes of remolding, handling, and placement) on the strength development of the geomaterial. The results of a series of experiments point to the possibility of improving the initial strength of SSTC for maritime fill work. Laboratory tests were performed to investigate the changes in and the recovery of the geomaterial strength brought about by one to three days of primary curing and the subsequent disturbances during various secondary curing times. In the field tests, three embankments, using SSTC that had previously undergone one or two days of primary curing, were constructed in seawater with an actual construction machine. The test results indicated that the initial strength of SSTC previously treated with one, two, or three days of primary curing increased to approximately 14 kN/m². The loss in strength that occurred at the primary stage of curing was recovered at a later stage of curing, namely, after 28 days, and the strength of the SSTC in the three embankments was 52–70% of the sample that was cured without primary disturbance. Larger amounts of disturbances were applied to the SSTC in the field tests than in the laboratory tests. The field tests produced submerged embankments, 1.8 m in height, with average slopes of 1:2.1–1:2.9, by undergoing one to two days of primary curing. The strength of the SSTC in all the embankments recovered significantly with time after construction, and the unconfined compressive strength of the SSTC exceeded 200 kN/m² at 100 days, which is deemed sufficient for the construction of embankments. Overall, it was confirmed that the one-day primary curing and the sea-bottom fill method presented better results than the two-day primary curing and the sea-surface fill method, considering the gradient of the slope and the strength-recovery characteristics of the SSTC.