The two-step electrosynthesis of nanocomposites of Ag, Au, and Pd nanoparticles with iron(ii) oxide-hydroxide

The two-step electrosynthesis of metal nanoparticle (MNP, M = Ag, Pd, and Au) nanocomposites with iron oxide-hydroxide FeO-xFe(OH)2 was investigated.

In Situ Synthesis of Surface-Mounted Novel Nickel(II) Trimer-Based MOF on Nickel Oxide Hydroxide Heterostructures for Enhanced Methanol Electro-Oxidation

Engineering the heterogeneous interface fusing MOFs and inorganic active component is an effective strategy to improve the electrochemical performance. Herein, we report a new Ni3-based MOF (denoted as CTGU-24) with an infrequent two-fold interpenetrating 3D (3,8)-connected network constructed from Ni(II) trimer and mixed tripodal tectonics for the electrocatalytic methanol oxidation reaction (MOR). In order to improve its stability and activities, the heterogeneous hybrid CTGU-24@NiOOH has been fabricated successfully via the first preparation of the NiOOH nanosphere and then in situ formation of CTGU-24 decorated on the NiOOH surface. Moreover, the integration of CTGU-24@NiOOH and different additives [acetylene black (AB) and ketjen black (KB)], resulting in the optimized hybrid sample AB&CTGU-24@NiOOH (4:4). It attains better MOR performance with an area-specific peak current density of 34.53 mA·cm−2 than pure CTGU-24 (14.99 mA·cm−2) and improved durability in an alkali medium. The new findings indicate that the CTGU-24@NiOOH heterostructure formed in situ and the integration of moderate additives are critical to optimizing and improving electrocatalytic activity of pure MOF crystalline material.

Kinetics of Electrochemical Nanonucleation by Induced Codeposition of Iron Group Metals with Refractory Metals (W, Mo, Re)

It is shown that the earlier discovered features of the composition and properties of electrochemical coatings obtained by the induced codeposition from alloys of iron group metals (W, Mo, Re) such as nanocrystallinity (X-ray amorphism), macroscopic dimensional effects of microhardness and corrosion resistance, the effect of the volume current density on the properties and composition are a consequence of the fractality of the solutions of complexes (citrate, gluconate, etc.) in combination with the intensive interfacial exchange. In this case, the kinetics of nano-nucleation limits the size of the resulting alloy nucleus, as a result of which water molecules participate in the formation of coatings, leading to the incorporation of oxide-hydroxide inclusions into the solid phase and hydrogenation.

STUDYING SOME OF THE MECHANICAL AND PHYSICAL PROPERTIES OF COLORED GEOPOLYMER CONCRETE

This study has been done to study the physical and mechanical characteristics of colored geopolymer concrete by adding two types of pigments yellow (iron oxide hydroxide) and blue (cobalt) with three additional proportions for each of the listed colors (0,2, 4, 6% wt), some materials which are available in the native market and other materials imported from outside of the country. The experimental investigation has dealt with the fresh properties(slump) of the colored geopolymer concrete mixes as well as some of the mechanical and physical characteristics of the hardened concrete by testing specimens in compressive strength, flexural strength, water absorption, Rebound number (RN), and ultrasonic pulse velocity (UPV). In addition to that, Finding a relationship between the destructive (strength of compressive) and (RN and UPV) tests. Show us that (2% wt) pigment percentage gives the best results.

Acid-basic properties of chromium(III) oxide surface

The article is devoted to the study of the nature and number of acid-base centers on the surface of chromium(III) oxide obtained by precipitation from an aqueous nitrate solution. The curve of the distribution of the number of acidbase centers of the samples is plotted depending on the indicator of the ionization constant of indicators. It was determined that the main Lewis centers make the main contribution to the acidity of the samples; there are also Bronsted centers of different acidity. A comparative analysis of the structural features of the surface of oxides of chromium, zinc and binary systems Cr (III)–Zn (II) was carried out according to the results of X-ray phase analysis of oxides and thermolysis of the corresponding hydroxides. Based on this, the possibility of obtaining nanosized catalysts based on oxide-hydroxide systems of chromium with a number of 3d-metals obtained in the process of polynuclear hydroxocomplexation is predicted.

Evolution of Sedimentary Basins as Recorded in Silica Concretions: An Example from the Ionian Zone, Western Greece

Chert concretions in thick limestone successions preserve a more complete paragenetic sequence of diagenetic minerals than their host limestone and interbedded shale. The goal of this study was to test the possible presence of a high-temperature mineralising system in the Ionian basin of western Greece. Upper Cretaceous chert nodules were sampled at Araxos, where rocks are highly faulted and uplifted by salt diapirism, and on Kastos Island, on the flanks of a regional anticline. Chert concretions have microporosity produced by recrystallisation of opal to quartz and fractures produced in the brittle chert during basin inversion. Diagenetic mineral textures were interpreted from backscattered electron images, and minerals were identified from their chemistry. Diagenetic minerals in pores and veins include sedimentary apatite (francolite), dolomite, Fe-chlorite, Fe oxide-hydroxide mixtures, sphalerite, barite and calcite. Sphalerite is restricted to Araxos, suggesting that inferred basinal fluids were hotter and more saline than at Kastos. At Araxos, the Fe oxide-hydroxide also includes minor Cu, Zn, and Ni. Whether the transported metals were derived from sub-salt clastic rocks and basement, or from enriched Mesozoic black shales, is unclear. The effectiveness of this novel approach to understanding fluid flow history in thick limestone successions is validated.