One step electrochemical fabrication of high performance Ni@Fe-doped Ni(oxy)hydroxide anode for practical alkaline water electrolysis

Oxygen evolution reaction (OER) is a rate-determining process in alkaline water electrolysis (AWE). Herein, we report a novel one-step oxidation-electrodeposition (OSOE) approach to generate core@shell nanoarrays-based AWE electrode with outstanding OER performances: an overpotential of 245 mV at 10 mA cm−2 (Tafel slope: 37 mV dec−1), and excellent stability under huge current densities. Moreover, the alkaline (AEL) cell equipped with NM-OSOE-23 anode recorded significant performance improvement of 200 mV lower voltage (2 A cm−1) compared with a similar cell used bare Ni mesh as an anode, which was contributed by notable enhancements of interface contact, anodic charge transfer, and mass transfer. These promising results are attributed to the constructed specific core@shell Ni@Fe-doped Ni(oxy)hydroxide nanoarray architecture on commercial nickel mesh. This study demonstrates this first reported OSOE can be commercialized to make highly efficient anodes enabling next-generation AWE

Ultra-High Molecular Weight Polyethylene Modifications Produced by Carbon Nanotubes and Fe2O3 Nanoparticles

Thin sheets of ultra-high molecular weight polyethylene (UHMWPE), both in pristine form and containing carbon nanotubes (CNTs) or Fe2O3 nanoparticles (NPs) at different concentrations, were prepared. The CNT and Fe2O3 NP weight percentages used ranged from 0.01% to 1%. The presence of CNTs and Fe2O3 NPs in UHMWPE was confirmed by transmission and scanning electron microscopy and by energy dispersive X-ray spectroscopy analysis (EDS). The effects of the embedded nanostructures on the UHMWPE samples were studied using attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy and UV–Vis absorption spectroscopy. The ATR-FTIR spectra show the characteristic features of the UHMWPE, CNTs, and Fe2O3. Concerning the optical properties, regardless of the type of embedded nanostructures, an increase in the optical absorption was observed. The allowed direct optical energy gap value was determined from the optical absorption spectra: in both cases, it decreases with increasing CNT or Fe2O3 NP concentrations. The obtained results will be presented and discussed

ARCHAEOMETRIC STUDY OF ANCIENT MAYA FIGURINES FROM THE COLLECTION OF THE NATIONAL MUSEUM

The paper presents the archaeometric study of a unique collection of ancient Maya figurines from the National Museum - Naprstek Museum collection in Prague, Czech Republic. The aim was to characterize ceramic materials of the figurines by three integral techniques (X-ray fluorescence, X-ray diffraction, simultaneous thermal analysis), in order to determine their chemical and mineralogical compositions and to assess possible similarities in the raw materials. The measured data were compared using statistical techniques in order to set up groups of samples according to the diversity in their composition. Further, the surface finishing was evaluated using micro-Raman spectroscopy, infrared spectroscopy, X-ray diffraction and transmission electron microscopy. A great diversity of ceramic bodies was proved. The compositions of figurines show 5 different groups with a varying ratio of main variables SiO₂, CaO and Al₂O₃. The analyses of decorative layers proved that the red pigment, which was used as an aesthetic coating of a jaguar figurine, contains primarily hematite. The other red pigments used to decorate frog and head figurines were of organic origin formed by cochineal dye. The nanostructured well-known artificial blue pigment Maya Blue was identified on the fragment of a bowl and a man figurine. The results document the material diversity of a unique collection of pre-Columbian ceramics

One step electrochemical fabrication of high performance Ni@Fe-doped Ni(oxy)hydroxide anode for practical alkaline water electrolysis

Oxygen evolution reaction (OER) is a rate-determining process in alkaline water electrolysis (AWE). Herein, we report a novel one-step oxidation-electrodeposition (OSOE) approach to generate core@shell nanoarrays-based AWE electrode with outstanding OER performances: an overpotential of 245 mV at 10 mA cm−2 (Tafel slope: 37 mV dec−1), and excellent stability under huge current densities. Moreover, the alkaline (AEL) cell equipped with NM-OSOE-23 anode recorded significant performance improvement of 200 mV lower voltage (2 A cm−1) compared with a similar cell used bare Ni mesh as an anode, which was contributed by notable enhancements of interface contact, anodic charge transfer, and mass transfer. These promising results are attributed to the constructed specific core@shell Ni@Fe-doped Ni(oxy)hydroxide nanoarray architecture on commercial nickel mesh. This study demonstrates this first reported OSOE can be commercialized to make highly efficient anodes enabling next-generation AWE