The electrocatalytic activity of YMnO3-based electrodes for the O2 and H2 evolution reactions in a strong alkaline medium

YMnO3 perovskites synthesized using the sol-gel method were studied regarding their electrocatalytic properties for the O2 and H2 evolution reactions (OER and HER) in a strong alkaline medium. The highest activity was observed during HER experiments, especially for the electrodes manufactured using suspensions containing Nafion, Carbon Black and either Co2+ doped YMnO3 or Sn2+ doped YMnO3. For these samples, the HER overpotential value at i = ─10 mA/cm2 was 0.83 V. The main conclusions are the following: (a) the inclusion of Carbon Black into the electrode manufacturing process improved the HER catalytic activity of all perovskite-modified electrodes and (b) the HER activity of the samples modified with the catalysts, Nafion and Carbon Black was similar despite the different temperatures applied during perovskite synthesis

Substitution effect on the physico-chemical properties in crednerite CuMnO2 type materials

Recently, the ABO2 delafossite-type class of materials, B being a transition element, has attracted a lot of interest. First of all in the field of transparent conducting oxides, thin films of CuAlO2 show the unusual combination of high transparency and rather high p-type semi-conductivity [1]. On the other hand, in the field of the exotic magnetic and structural properties, a good example is the CuFeO2 delafossite, a triangular lattice antiferromagnet which has been extensively studied over the last years for its multiferroïcity [2,3]. The ABO2 delafossite structure, where A=Cu and Ag, and B a transition element, belongs to the R-3m space group and is characterised by O-Cu-O dumbells linking layers of edge sharing BO6 octahedra. However, in this class of materials,crednerite CuMnO2occupies a unique placedue to the Jahn-Teller (JT) distortion of the Mn3+ (t2g 3 eg) which leads to a monoclinic structure (C2/m space group at room temperature) and to a different topology of the magnetic triangular lattice and out-of-plane stacking sequence compared to delafossite structure. In this work, we investigated the physico-chemical properties of CuMn1-XBXO2 (B=Al, Mg; x=0 - 0.08) type materials by X-Ray diffraction, SEM-EDAX, thermal analysis, UV-VIS and infrared spectroscopy. The effect of the substitution on the lattice parameter in CuMnO2is significant in order to understand the correlation between the structure and the properties in this compound.The crednerite nanoparticles were synthesized at low temperature by hydrothermal method in teflonlined steel autoclave

Effect of synthesis method on the structure and properties of perovskite NaNbO3 type nanomaterials

Ferroelectric nanostructures have attracted much attention recently due to the ongoing demand for miniaturization of devices and discover new phenomena. One of the materials studied intensively in recent years is potassium niobates with perovskite structure is a promising material for electro-optic, nonlinear optical, and photorefractive applications such as frequency doubling, wave guiding, and holographic storage. The structure and morphology of NaNbO3 perovskites are studied in the context of their possible use for sensors application. Materials are prepared by hydrothermal, sol-gel and ultrasonic method using different thermal treatments. Powders obtained were characterized by X-Ray diffraction (XRD), scanning electron microscopy (SEM) and Fourier Transform Infrared Spectroscopy (FTIR)

Removal of humic acid from water by sorption

In this research, several sorption material types, i.e., zeolite (A), activated carbon (B), the mixture of 50wt.% zeolite and 50wt.% activated carbon (C); 70wt.% zeolite and 30wt.% activated carbon (D); the mixture of 30wt.% zeolite and 70wt.% activated carbon (E) were tested to examine the application for HA removal by sorption process. The structure of natural zeolite and activated carbon was examined by instrumental analysis methods, i.e., X-ray diffraction (XRD) and scanning electron microscopy (SEM/EDX). From the sorption studies, the mixture of 50 wt. % zeolite and 50 wt. % activated carbon was chosen to be the best composition for further studies regarding the advanced composite material for humic acid removal from water