玲珑金矿田含矿断裂的基岩地球化学特征及找矿潜力评价

基岩地球化学方法广泛应用于地质找矿与生产实践,是开展深部找矿预测最直接的方法和手段。通过对玲珑金矿田井下含矿断裂和招平断裂的基岩剖面地球化学特征进行系统研究,得出以下认识：玲珑金矿田原生晕最佳指示元素组合为Au、Ag、Bi、As和Co,且Au-Ag、Au-Bi、Au-As及Au-Co元素之间呈较好的幂指数正相关。根据玲珑金矿田已探明矿脉最佳指示元素组合的统计结果,结合招平断裂基岩剖面地球化学测量结果,发现招平断裂在地表有2处金矿化异常,推测其为矿致异常,反映出该地段具有较好的找矿潜力,特别是前花园村东1021剖面中异常找矿潜力更大。     

Nanofiber-based Sm0.5Sr0.5Co0.2Fe0.8O3-δ/N-MWCNT composites as an efficient bifunctional electrocatalyst towards OER/ORR

It is of significance to search non-noble metal OER/ORR catalysts with perfect performance. The introduction of carbon into perovskite can significantly enhance oxygen electrocatalytic activity. Herein, nanofiber-based Sm_0.5Sr_0.5Co_0.2Fe_0.8O_3-δ/rGO (SSCF28/rGO) and Sm_0.5Sr_0.5Co_0.2Fe_0.8O_3-δ/N-MWCNT (SSCF28/N-MWCNT) hybrids with various mass ratios were synthesized successfully by a facile ultrasonic mixing method and their oxygen evolution reaction (OER)/oxygen reduction reaction (ORR) properties were compared and studied. In 0.1 M KOH, SSCF28/N-MWCNT = 1.3 with optimal mass ratio shows better OER/OER bifuntional catalytic activity than SSCF28/rGO = 2:1. After 1000 CV cycles, SSCF28/N-MWCNT = 1.3 remains stable. Compared to SSCF28/rGO = 2:1, SSCF28/N-MWCNT = 1:3 shows promising practical applicability in metal-air batteries. The excellent OER/ORR activity of SSCF28/N-MWCNT = 1:3 can be attributed to the component optimization of perovskite and carbon and the synergistic effect between nanofiber-structured SSCF28 and N-functionalized MWCNT (N-MWCNT).     

镀银粉煤灰制备及其在柔性导电膜中的应用

目的 在粉煤灰表面镀银,以优化粉煤灰在柔性基体中的润湿性,提高其与柔性基体之间的界面结合力.方法 首先对粉煤灰进行高温碱洗、粗化、敏化和活化预处理,随后进行化学镀银,通过研究镀液中硝酸银、氨水和甲醛用量等工艺参数,获得导电性能优异且镀层致密、均匀的镀银粉煤灰(简称Ag/FA)粉末.最后将导电性最佳的Ag/FA粉末作为中间填料,以液体硅橡胶为柔性基体,二甲苯为溶剂,制备三明治结构柔性导电膜.采用扫描电子显微镜(SEM)、透射电子显微镜(TEM)、X-射线衍射仪(XRD)以及电阻率测试仪等设备,对不同影响因素下Ag/FA粉末与柔性导电膜的微观形貌、组成和导电性进行表征.结果 研究结果显示,粉煤灰镀银最佳配方为:硝酸银10 g/L,氨水40 mL/L,甲醛40 mL/L,温度30℃,时间30 min.该工艺条件下,Ag/FA粉末的体积电阻率可达4.68×10?4?·cm.当Ag/FA粉末在柔性硅胶膜中的质量分数为7.69％时,即可形成完整的导电通路;继续增加至25％时,三明治结构柔性导电膜的导电性优异,体积电阻率可达2.65×10?3?·cm,可反复折叠、弯曲和拉伸.结论 采用简单的化学镀银工艺可使粉煤灰表面导电功能化,改善其与柔性聚合物材料之间的结合力,开拓功能化粉煤灰在电磁屏蔽和柔性电子材料领域的应用.     

麻家梁矿特厚煤层综放工作面瓦斯抽采方案优化

针对麻家梁煤矿4#煤层瓦斯绝对含量较小、透气性系数低、自然涌出衰减快、不能进行采前预抽的问题,采用项板抽放巷封闭抽放工作面采空区瓦斯的方法,通过对地面瓦斯抽采方案进行优化,综放工作面采空区的瓦斯抽放量为8～10 m3/min,占采空区瓦斯涌出量的40％～60％,解决了综放工作面上隅角瓦斯超限的问题.     

Quick-to-synthesize hybrid electrodes composed of activated carbon cloth with Co/Fe-based films as bifunctional electrocatalysts for water splitting

Hybrid electrodes have recently been investigated as attractive alternatives to noble-metal-based electrocatalysts for hydrogen production by water splitting. Herein, we propose an electrode composed of an oxidized carbon cloth with an electrodeposited bimetallic Co/Fe-based film. By optimizing the electrodeposition conditions and applying electrochemically activated carbon cloth as a substrate, one can prepare a free-standing noble-metal-free electrocatalytic electrode with high bifunctional electrocatalytic activity in hydrogen and oxygen evolution from alkaline solution. The developed Fe_0.25Co_0.75 electrode requires overpotentials of 245 mV for HER and 360 mV for OER at high current densities of −100 and 100 mA cm⁻², respectively. Furthermore, its overall synthesis time from commercially available raw materials is only approximately 20 min. The electrode material was used as both a cathode and an anode in the model electrolyzer, which can deliver 10 mA cm⁻² of current density at 1.66 V without loss of activity during 100 h of performance.     

An efficient and durable bifunctional electrocatalyst based on PdO and Co2FeO4 for HER and OER

The adoption of effective, minimal, and versatile electrocatalysts for water splitting to generate hydrogen fuels is of critical importance. The bulk of newly described materials have considerable onset potential, but their electrocatalytic activity is limited by weak electrical conductivity and a limited range of catalytic sites. The combination of a few precious metals added with transition metal-based compounds is a novel and captivating approach. Herein, cobalt ferrite oxide (Co₂FeO₄) @ palladium oxide (PdO) nanostructures have been prepared through the combined use of hydrothermal and ultraviolet (UV) irradiation techniques. For hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) kinetics, the modified composition offers a high concentration of active sites, improved electrical conductivity, and stability. The Co, Fe, and Pd ions at the composite system's interface may affect the adsorption energy of reaction intermediates synergistically, enabling the process to continue with less potential. The electrocatalyst Co₂FeO₄@PdO demonstrates an excellent bifunctional approach to electrochemical water splitting (EWS) for HER and OER in alkaline medium. As-prepared electrocatalyst shows an overpotential value of 269 and 259 mV for HER and OER at 10 and 20 mA/cm² current densities respectively. The low charge transfer resistance values such as 72.2 and 62.4 Ω and durability for 48 h has been observed toward HER and OER, support this material as an efficient and durable electrocatalyst for energy conversion systems.     

Feasibility study of a mini fuel cell to detect interference from a cellular phone

Fuel cells produce electricity without involving combustion processes. They generate no noise, vibration or air pollution and are therefore suitable for use in many vibration-free power-generating applications. In this study, a mini alkaline fuel cell signal detector system has been designed, constructed and tested. The initial results have shown the applicability of such system for used as an indicator of signal disturbance from cellular phones. A small disturbance even at 4 mV cm⁻¹, corresponding to an amplitude of 12–18 mG in terms of electromagnetic field, can be well detected by such a device. Subsequently, a thermodynamics model has been developed to provide a parametric study by simulation to show the likely performance of the fuel cell alone in other environments. As such the model can provide many useful generic design data for alkaline fuel cells. Two general conclusions can be drawn from the present theoretical study: (i) fuel cell performance increases with temperature, pressure and correction factor, C_f; (ii) the temperature factor (E/T) increases with increasing temperature and with increasing pressure factor.     

Fuel-cell powered uninterruptible power supply systems: Design considerations

A 1-kVA fuel cell powered, line-interactive uninterruptible power supply (UPS) system that employs modular (fuel cell and power converter) blocks is introduced. Two commercially available proton-exchange membrane fuel cell (25–39 V, 500 W) modules together with suitable dc–dc and dc–ac power electronic converter modules are employed. A supercapacitor module is also used to compensate for the instantaneous power fluctuations and to overcome the slow dynamics of the fuel processor (reformers). Further energy stored in the supercapacitor is also utilized to handle a momentary overload such as 200% for a short duration. Due to the absence of batteries, the system satisfies the demand for an environmentally clean source of energy. A complete design that defines the amount of hydrogen storage required for a power outage of 1 h, and the sizing of the supercapacitors for transient load demand is presented for a 1-kVA UPS.     

Geometric structures and hydrogen storage properties of M2B7 (M=Be,Mg, Ca) clusters

Based on the density functional theory, we investigate the electronic properties of the clusters M₂B₇ (M = Be, Mg, Ca) and their hydrogen storage properties systematically in this paper. Extensive global search results show that the global minimal structures of the three systems (Be₂B₇, Mg₂B₇ and Ca₂B₇) are heptagonal biconical structure, and the two alkaline earth metals are located at the top of the biconical. Chemical bonding analyses show that M₂B₇ clusters have 6σ and 6π delocalized electrons, which are doubly aromatic. At the wB97XD level, the three systems have good hydrogen storage capabilities. The hydrogen storage density of Be₂B₇ is as high as 23.03 wt%, while Mg₂B₇ and Ca₂B₇ also far exceed the hydrogen storage target set by the U.S. Department of Energy in 2017. Their average adsorption energies of H₂ molecules all ranged from 0.1 eV/H₂ to 0.48 eV/H₂, which is fall in between physisorption and chemisorption. Extensive Born Oppenheimer molecular dynamics (BOMD) simulations show that the H₂ molecules of the three systems can be completely released at a certain temperature. Therefore, M₂B₇ systems can achieve reversible adsorption of H₂ molecules at normal temperature and pressure. It can be seen that the B₇ clusters modified by alkaline earth metals may become a promising new nano-hydrogen storage material.     

Construction of P,N-codoped carbon shell coated CoP nanoneedle array with enhanced OER performance for overall water splitting

Water electrolysis to generate hydrogen (H₂) and oxygen (O₂) was a sustainable alternative for clean energy in the future but remained challenging. Herein, we fabricated a nanoneedle-like CoP core coated by a P,N-codoped carbon shell (CoP@PNC@NF). The hierarchical structure, unique nanoneedle-like morphology, CoP core, and P,N-codoped carbon shell were responsible for the high electrocatalytic activity. Electrocatalytic tests demonstrated that CoP@PNC@NF displayed low overpotentials of 137.6 and 148.4 mV, as well as Tafel slopes of 59.89 and 56.40 mV dec⁻¹ for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER), respectively, at 10 mA cm⁻² in 1.0 M KOH. The bifunctional electrocatalyst CoP@PNC@NF also exhibited a low cell voltage of 1.458 V to yield 10 mA cm⁻² in the two-electrode system and could maintain the activity for 50 h. The Faradaic efficiencies of CoP@PNC@NF for both HER and OER were nearly 100%. The result outperformed the precious-metal-based electrocatalyst apparatus (RuO₂||Pt/C) and other carbon-coated transition-metal phosphides (TMPs). This work paved the way for the rational design of carbon shell-coated TMPs with low energy barriers for converting and storing electrochemical energy.