Facile Synthesis of Porous Hexapod Ag@AgCl Dual Catalysts for In Situ SERS Monitoring of 4-Nitrothiophenol Reduction

Controllable morphological metal catalytic materials have always been a focus in research. In the previous work, hexapod AgCl was successfully synthesized. In this paper, hexapod Ag@AgCl microstructures with diverse Ag contents are prepared through NaBH4 reduction. They are characterized by scanning electron microscopy (SEM) and the element distribution is proved by an energy dispersive X-ray spectrometer (EDS). They are porous dendritic microstructures with a large specific surface area and a rough surface, which display high catalytic performance and surface-enhanced Raman spectroscopy (SERS) activity. Furthermore, the hexapod Ag@AgCl microstructure is devoted as a dual catalyst to monitor the reduction of 4-nitrothiophenol (4-NTP) to 4-aminothiophenol (4-ATP) in situ using SERS. Ultraviolet–visible (UV–Vis) spectroscopy was employed to evaluate the catalytic performance of the hexapod Ag@AgCl microstructures. The consequences show that the velocity of reaction became faster with a corresponding increase in silver content and the reaction mechanism was cleared. In addition to preparing a good catalyst, this work also promotes the combination of micro-nano materials and spectroscopy technology.

The Effects of Mo and Nb on the Microstructures and Properties of CrFeCoNi(Nb,Mo) Alloys

The effects of niobium and molybdenum additions on the microstructures, hardness and corrosion behaviors of CrFeCoNi(Nb,Mo) alloys were investigated. All of the CrFeCoNi(Nb,Mo) alloys displayed dendritic microstructures. The dendrites of CrFeCoNiNb and CrFeCoNiNb0.5Mo0.5 alloys were a hexagonal close packing (HCP) phase and the interdendrites were a eutectic structure of HCP and face-centered cubic (FCC) phases. Additionally, the dendrites of CrFeCoNiMo alloys were a simple cubic (SC) phase and the interdendrites were a eutectic structure of SC and FCC phases. The volume fraction of dendrites and interdendrites in these alloys were calculated. The influences of the volume fraction of dendrite in the alloys on the overall hardness were also discussed. The CrFeCoNiNb alloy had the larger volume fraction of dendrite and thus had the highest hardness among these alloys. The CrFeCoNi(Nb,Mo) alloys also showed better corrosion resistances in 1 M H2SO4 and 1 M NaCl solutions by comparing with commercial 304 stainless steel. The CrFeCoNiNb0.5Mo0.5 alloy possessed the best corrosion resistances in these solutions among the CrFeCoNi(Nb,Mo) alloys.

Bronze Jewellery from the Early Iron Age urn-field in Mała Kępa. An approach to casting technology

This study characterizes the bronze jewellery recovered from the Lusatian culture urn-field in Mała Kępa (Chełmno land, Poland). Among many common ornaments (e.g. necklaces, rings, pins) the ones giving evidence of a steppe-styled inspiration (nail earrings) were also identified. With the dendritic microstructures revealed, the nail earrings prove the implementing of a lost-wax casting method, whereas some of the castings were further subjected to metalworking. The elemental composition indicates the application of two main types of bronze alloys: Cu-Sn and Cu-Sn-Pb. It has been established that the Lusatian metalworkers were familiar with re-melting the scrap bronze and made themselves capable of roasting the sulphide-rich ores.The collection from Mała Kępa has been described in terms of its structure and composition. The investigations were made by means of the energy dispersive X-ray fluorescence spectroscopy (ED-XRF), scanning electron microscopy (SEM) coupled with an energy dispersive X - ray analysis system (EDS) and optical microscopy (OM). In order to fingerprint an alloy profile of the castings with a special emphasis on the nail earrings, the data-set (ED-XRF, EDS) was statistically evaluated using multidimensional analyses (FA, DA).