Amorphous-crystalline cobalt-molybdenum bimetallic phosphide heterostructured nanosheets as Janus electrocatalyst for efficient water splitting

Efficient and sustainable Janus catalysts toward hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) are highly desirable for future hydrogen production via water electrolysis. Herein we report an active Janus electrocatalyst of amorphous-crystalline cobalt-molybdenum bimetallic phosphide heterostructured nanosheets on nickel foam (CoMoP/CoP/NF) for efficient electrolysis of alkaline water. As-reported CoMoP/CoP/NF consists of amorphous bimetal phosphide nanosheets doped with crystalline CoMoP/CoP heterostructured nanoparticles on NF. It can efficiently catalyze both HER (η = 127 mV@100 mA cm^?2) and OER (η = 308 mV@100 mA cm^?2) in alkaline electrolyte with long-term durability. Serving as anode and cathode of water electrolyzer, CoMoP/CoP/NF generates electrolytic current of 10, 50 and 100 mA cm^?2 at low voltage of 1.50, 1.59, and 1.67 V, respectively.     

Combining molybdenum carbide with ceria overlayers to boost Mo/CeO2 catalyzed ammonia synthesis

The design of an efficient non-noble metal catalyst is of burgeoning interest for ammonia synthesis. Herein, we report a Mo₂C/CeO₂ catalyst that is superior in ammonia synthesis activity. In this catalyst, molybdenum carbide coexisted with the ceria overlayers which is from the ceria support as the strong metal–support interaction. There is a high proportion of low-valent Mo species, as well as high concentration of Ce³⁺ and surface oxygen species. The presence of Mo₂C and CeO₂ overlayers not only leads to enhancement of hydrogen and nitrogen adsorption, but also facilitates the desorption and exchange of adsorbed species with the gaseous reagents. Compared with the Mo/CeO₂ catalyst prepared without carbonization, the Mo₂C/CeO₂ catalyst is more than sevenfold higher in ammonia synthesis rate. This work not only presents an explicit example of designing Mo-based catalyst that is highly efficient for ammonia synthesis by tuning the adsorption and desorption properties of the reactant gases, but opens a perspective for other elements in ammonia synthesis.     

河北、湖北、四川三省畜禽养殖场粪污样品中硒、钼含量的调查

目的 调查河北、湖北、四川三省畜禽养殖场粪污样品中硒、钼的含量。方法 采集河北、湖北、四川三省206个养殖场的422个样品, 干清粪和水泡粪样品经过65 ℃烘干至恒重后, 粉碎或研磨, 过0.25 mm样品筛, 进行微波消解处理后, 赶酸定容至50 mL容量瓶中, 用电感耦合等离子质谱仪对硒、钼元素进行测定。污水样直接进行微波消解处理后, 赶酸定容至50 mL容量瓶中, 用电感耦合等离子质谱仪对硒、钼元素进行测定。结果 3个省份的猪场、鸡场和牛场的干清粪样品中不同程度的检出了硒或钼的含量; 污水样品和水泡粪样品中均未检出硒和钼的含量。结论 河北、四川、湖北三省养猪场、养鸡场和养牛场的粪污再利用过程中可能会对环境造成一定的污染, 应当进行相应处理后再进行利用。     

润滑脂的溶解及铁谱分析试验研究

针对润滑脂由于流动性差而无法直接采用铁谱技术进行磨粒分析的问题,探讨适合溶解不同润滑脂的有机溶剂。选择锂基、钙基和铝基3种目前设备润滑常用的润滑脂,通过水浴加热与超声波震荡的溶解方法,对比研究8种有机溶剂对润滑脂的溶解效果;通过摩擦试验制备带有磨粒的润滑脂试样,通过旋转式铁谱仪进行制谱试验,并结合显微镜分析谱片磨粒沉积效果。结果表明:正己烷溶液、体积分数30%二甲苯和70%正己烷混合溶液适合溶解锂基润滑脂,二甲苯和四氯乙烯适合溶解钙基润滑脂和铝基润滑脂;将润滑脂试样溶液的黏度稀释到4 mm~2/s以下时,在旋转式铁谱仪上能够获得良好的制谱效果。     

Theoretical kinetic study of the reaction between dimethyl disulfide and OH radicals

The potential energy profile of the reaction between dimethyl disulfide and OH^? radicals is explored by utilizing ab initio and hybrid meta density functional theory methods. Having the energies and structural data of the stationary points, statistical rate theories, such as transition state theory and variable reaction coordinate-transition state theory, are employed to compute the overall rate constants, and discuss the mechanism and product channels. On the basis of the calculations, the overall rate coefficient is predicted to be 2.49?×?10^?10?cm³?molecule^?1?s^?1 at 298?K. It is found that in the most favorable pathway, the reaction proceeds via formation of the relatively unstable intermediate CH₃S^?(OH)SCH₃ decomposing rapidly to yield CH₃S^?+CH₃SOH.     

Improvement of quantitative analysis of molybdenum element using PLS-based approaches for laser-induced breakdown spectroscopy in various pressure environments

An experimental setup has been designed and realized in order to optimize the characteristics of laser-induced breakdown spectroscopy system working in various pressure environments. An approach combined the normalization methods with the partial least squares(PLS) method are developed for quantitative analysis of molybdenum(Mo) element in the multi-component alloy,which is the first wall material in the Experimental Advanced Superconducting Tokamak. In this study, the different spectral normalization methods(total spectral area normalization,background normalization, and reference line normalization) are investigated for reducing the uncertainty and improving the accuracy of spectral measurement. The results indicates that the approach of PLS based on inter-element interference is significantly better than the conventional PLS methods as well as the univariate linear methods in the various pressure for molybdenum element analysis.     

Enhanced visible-light-assisted photocatalytic hydrogen generation by MoS2/g-C3N4 nanocomposites

A facile, one-pot, solvothermal synthesis of MoS₂ microflowers (S1) and the heterostructures MoS₂/g-C₃N₄ with varying ratios of 1:1 (S2), 1:2 (S3) and 1:3 (S4) exhibiting enhanced visible-light-assisted H₂ generation by water splitting has been reported. The compounds were thoroughly characterized by PXRD, FESEM, HRTEM, EDS, UV–vis and XPS techniques. FESEM and HRTEM analyses showed the presence of microflowers composed of nano-sized petals in case of pure MoS₂ (S1), while the MoS₂ microflowers covered with g-C₃N₄ nanosheets in case of MoS₂/g-C₃N₄ heterostructure, S4. XPS analysis of S2 showed the presence of 2H phase of MoS₂ with g-C₃N₄. The Eosin-Y/dye-sensitized visible-light-assisted photocatalytic investigation of the samples in the absence of any noble metal co-catalyst revealed very good water splitting activity of MoS₂/g-C₃N₄ heterostructure, S2 with hydrogen generation rate of 1787 μmol h⁻¹g⁻¹ which is about 6 and 40 times higher than pure MoS₂ and g-C₃N₄ respectively. The relatively higher catalytic activity of the heterostructure, S2 has been ascribed to the efficient spatial separation of photo-induced charge carriers owing to the synergistic interaction between MoS₂ and g-C₃N₄. A possible mechanism for the Eosin-Y-sensitized photocatalytic H₂ generation activity of MoS₂/g-C₃N₄ heterostructures has also been presented. The enhanced activity of S2 was further supported by fluorescence measurements. Thus, the present study highlights the importance of non-noble metal based MoS₂/g-C₃N₄ heterojunction photocatalysts for efficient visible-light-driven H₂ production from water splitting.     

破碎方式对白鲢鱼糜凝胶结构的影响

与斩拌方式对比,研究搅拌方式对鱼糜制品凝胶特性的影响。结果表明,搅拌破碎使白鲢鱼糜的凝胶强度及持水力增加,提高了硬度、黏附性、胶黏性和咀嚼性,但是对白度无明显影响。在2%和3%盐添加量的条件下,搅拌破碎对鱼糜制品的质构改善效果显著,凝胶强度分别提高了70.2%,66.7%。根据鱼糜的盐溶蛋白、肌动球蛋白的活性巯基含量、化学作用力和浊度结果可知,搅拌破碎可以增加活性巯基含量,使得更多的巯基氧化成二硫键,提高疏水相互作用,促进蛋白分子间的聚集,浊度增加,三维凝胶网络结构更致密。     

国产特殊装备用润滑脂的研制

为满足特殊装备使用中的润滑需求,选取聚α-烯烃和酯类油的混配油作为基础油,锂皂作为稠化剂,以纳米MoS_2作为极压抗磨剂,月桂酰胺丙基氧化胺作为助分散剂,月桂酰胺丙基氧化胺与二硫化钼质量比为1∶5,选用酚胺混合型抗氧剂,加入防锈剂C 1%,通过直接皂化的方法制备了一种新型润滑脂,纳米MoS_2和月桂酰胺丙基氧化胺在皂化反应阶段加入。该润滑脂的各项理化性能与现用商品润滑脂相当,且解决了现用润滑脂固体添加剂的团聚和沉降问题,提高了润滑脂的分散稳定性,综合性能优良,可以满足某特殊装备的润滑使用需求。