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Hydrogen Oxidation Reaction (HOR) is anode reaction in Proton exchange membrane fuel cells (PEMFCs) and it has very fast kinetics. However, the purity of fuel (H 2) is very important and can slow down HOR kinetics, affecting the overall PEMFC performance. The performance of commercial Pt/C catalyst impregnated with WO x, as a catalyst for HOR, was investigated using a set of electrochemical methods (cyclic voltammetry, linear scan voltammetry and rotating disk electrode voltammetry). In order to deepen the understanding how WO x species can contribute CO tolerance of Pt/C, a particular attention was paid to CO poisoning. In the absence of CO, HOR is under diffusion limitations and HOR kinetics is not affected by WO x species. Appreciable HOR current on the electrodes pre-saturated with CO ads at potentials above 0.3 V vs. RHE, which is not observed for pure Pt/C, was discussed in details. HOR liming diffusion currents for higher concentrations of W are reached at high anodic potentials. The obtained results were explained by donation of OH ads by WO x phase for CO ads removal in the mid potential region and reduced reactivity of Pt surface sites in the vicinity of the Pt|WO x interface. The obtained results can provide guidelines for development of novel CO tolerant PEMFC anode catalysts. Image 1 • HOR and CO tolerance of Pt/C mixed with WO x is analyzed in parallel. • HOR activity of Pt/C catalyst is not affected by mixing with WO X. • CO tolerance of Pt/C catalyst is improved by mixing with WO X. • When Pt/C is mixed with WO x HOR in the presence of CO commence at E > 0.3 V vs. RHE. • Only a small Pt.|WO x interfacial region is responsible for altered catalyst behavior [ABSTRACT FROM AUTHOR]

Polycyclic aromatic hydrocarbons (PAHs) are denoted by International Agency for Research on Cancer as mutagens, teratogens and carcinogenic to humans. In 2013, Vinča Institute of Nuclear Sciences was hired to determine whether PAHs are present in significant quantities in the concrete walls of newly built residential buildings (about 15,000 m 2 of apartments), and to propose appropriate technical solution for PAH removal in this case. As PAH occurrence, determination and remediation in concrete is, to our knowledge, a completely new field, it was necessary to face a number of challenges, including lack of regulations considering contents of PAHs in concrete, investigation of the origin of PAH contamination in concrete (if established), as well as finding feasible and non-expensive remediation method, which would be appropriate for residential space. In first part of this study, a markedly high concentrations of 5 PAHs were detected by UPLC/PDA analysis in samples of both concrete walls and mineral oil used for coating of planks during formwork, while control concrete and mineral oil, taken from independent construction site, were taken as a reference. Such coincidence, as well as the fact that mineral oil has penetrated into the concrete which is proven by ASAP/MS analysis, pointed to the mineral oil as the most probable source of PAH contamination of the concrete. In the second part, an efficient and easy-applicable method for PAH oxidation in concrete (called FHO3AOP), using UV light, H 2 O 2 and ozone, was presented and discussed in terms of previous literature data. [ABSTRACT FROM AUTHOR]

Polycyclic aromatic hydrocarbons (PAH) have been listed by the United States Environmental Protection Agency (US EPA) and by the European Community as priority environmental pollutants. The removal of PAHs from soils, sediments and waste water has attracted attention of scientists and engineers for several decades. Electrochemical oxidation of PAH compounds in water, is receiving increasing attention, due to its convenience and simplicity. In this study we performed electrochemical oxidation of 16 EPA PAHs mixture in 10% NaCl aqueous solution in potentiostatic conditions, at voltage 1 V. Decrease of concentration of some individual PAHs, up to 70% referred to their starting concentration, after 60 min of electrolysis, was confirmed by UPLC/PDA analysis. In further work investigation was extrapolated to in situ removal of PAHs from concrete, as the medium where, to our knowledge, such way of PAH removal has not been investigated before. High concentrations of PAH contamination occurred in the concrete structure of the residential buildings in Belgrade in 2014. Application of DC voltage of 50 V between nickel and stainless steel electrodes packed in the concrete wall, moisturized with the 10% NaCl solution, led to considerable removal of the pollutants by oxidation process throughout the concrete. [ABSTRACT FROM AUTHOR]

• Methodology for determining the corrected work index with non-standard feed size. • The presented model is valid only for ores with a typical Hukki exponent. • The presented procedure is not limited in terms of the use of a closing screen size. The grindability of raw material is generally determined by Bond's standard ball mill grindability test (developed by the Allis Chalmers company). The ball mill grindability test is used for describing ore hardness and it is so widespread that the Bond Work Index generated from the test is often referred to as an ore characteristic. The ore resistance to grinding and energy consumption can be expressed using the work index and Bond's Third Theory. The Bond Third Theory method is widely used in the design of the grinding cycle, selection of grinding equipment, determination of required grinding power, and performance evaluation of the process. Despite widespread use for more than seventy years, doing a precise and complete Bond test can be challenging due to a variety of restrictions imposed by Bond. The initial size of the sample is strictly defined to be −3.35 mm. This paper describes the methodology for the determination of the Bond work index when coarse or fine raw material is found in the initial sample (i.e. when the initial sample not less than 3.35 mm). [ABSTRACT FROM AUTHOR]

Tungsten carbide (WC) is in the focus of current research as a suitable electrocatalyst support. Typically, supported monometallic system are investigated, in spite the fact that practice in catalysis shows that multimetallic systems can have significantly better performance compared to monometallic counterparts. In this work, WC-supported Pd 3 Au overlayers were studied theoretically using periodic Density Functional Theory calculations and compared to bulk-like Pd 3 Au and pure Pd. Stability of studied surfaces and the electronic structures were analyzed. Chemisorption properties were probed using atomic H and CO molecule. Electrocatalytic activities of studied surfaces were estimated using hydrogen binding energy as catalytic activity descriptor for hydrogen electrode reactions. The connection between H binding energy and CO adsorption energy enabled us to establish the link between catalytic activity and CO tolerance of studied surfaces. It is considered that formation of bimetallic layers on WC opens a new perspective in designing new core-shell electrocatalysts with high performance and significantly reduced content of noble metals. [ABSTRACT FROM AUTHOR]

Abstract: In this work WC-supported metal monolayers (Cu, Ru, Rh, Pd, Ag, Ir, Pt and Au) are investigated using Density Functional Theory in order to establish general trends regarding monolayer stability, electronic structure and reactivity. Using calculated hydrogen–metal bond energies and available data on the exchange current densities (j 0) for hydrogen evolution reaction (HER) volcano-type curve is obtained enabling prediction of HER j 0 for the entire series of MML/WC systems not considered so far as HER electrocatalysts. Among investigated surfaces, CuML/WC(0001) and RhML/WC(0001) are identified as promising HER electrocatalysts with (i) HER exchange current density matching the one of Pt and (ii) stability in electrochemical environment under HER conditions. Provided results point to a general conclusion that Pt might not be necessary for efficient catalysis of hydrogen electrode reactions – superior catalysts can be obtained by rational design approach with suitable choice of overlayer/support system not involving Pt at all. [Copyright &y& Elsevier]

Abstract: There are several problems which are holding back the use of fuel cells. The utilization of fuel cells depends on the start-up costs which are very high due to the use of expensive materials for their construction. In that respect, we describe a cost-effective alkaline fuel cell (AFC) that uses solid, polymer based, membrane instead of conventionaly used, highly concentrated, corrosive, liquid alkaline electrolyte. This approach to AFC is potentially the basis of a simple, low-cost system, that can solve one of the problems of the highly-efficient and environment-friendly AFC. The focus of this paper are low cost composite alkaline membranes, based on poly(vinyl alcohol) (PVA). The PVA matrix is made by solution cast method and gamma irradiation crosslinking. Three different types of membranes are obtained in this manner – plain PVA membrane, PVA membrane cross-linked using gamma irradiation (γ-PVA) and composite PVA membrane doped with Mo (PVA-Mo). These membranes are immersed in the alkaline solution and investigated as anion exchange membranes. The performance of the solid alkaline fuel cells (SAFCs) containing these PVA membranes has been studied under hydrogen and oxygen gas flow on the Pt/C catalyst. Both, γ-PVA and PVA-Mo membranes are modified to absorb larger amounts of alkaline solution than the PVA membrane, thus greatly improving the performance of the SAFC, in terms of output power. This is clearly indicated in the polarisation curves. The electrochemical impedance spectroscopy measurements during the SAFC operation were also performed to give better insight in the effect observed. Investigation presented in this paper clearly indicates that solid alkaline PVA membranes can be used for the construction of the SAFCs. [Copyright &y& Elsevier]

• The determination of the Bond work index (BWI) on finer samples. • Accurate determination of the (BWI) is essential for the proper design plant. • Suggested equation for determination BWI on finer samples. • The error is smaller than 2.5%. The Bond work index (BWI) is a well-known method used when selecting comminution equipment, to evaluate the grinding efficiency and to calculate the required grinding power. Although considered an industry standard, Bond did not fully define that procedure, and therefore significant discrepancies in test results can sometimes be obtained due to some undefined steps in the method. One of these cases is the initial sample size for grinding, why it must be the initial sample size of 3.35 mm, and whether it is possible to determine the BWI on samples of finer classes. In practice, it is possible to find materials whose size is finer than 3.35 mm. This paper examines the determination of the BWI on finer samples and proposes an equation for the determination of the BWI on finer samples. [ABSTRACT FROM AUTHOR]

The article presents promising catalysts, applicable for direct alcohol fuel cells (DAFC) for portable and mobile applications. The goal of this work is development of Pt and Pd catalysts deposited on interactive nanocrystalline Ru doped SnO 2 support with improved performance. The structure and the morphology of the prepared metal-oxide catalyst support and Pt and Pd based catalysts were examined using XRPD, SEM/EDX and TEM techniques. Electrocatalytic activities of the prepared Pt or Pd based catalysts were evaluated in both alkaline and acidic conditions. The ethanol oxidation reaction (EOR) was studied using conventional electrochemical techniques. The interactive nature of the novel Ru doped SnO 2 catalyst support was confirmed, resulting in the enhancement of the EOR kinetics, in comparison to commercially available catalysts. New and simplified synthetic route applied for preparation of interactive catalyst support was presented with the aim to enable easy scale-up of the catalyst production process. Obtained results on the novel catalysts promise great potential in improving the performance and durability of the DAFC. [Display omitted] • Pt and Pd deposited on Ru–SnO 2 nanocrystalline support for EOR in FC applications. • Ru-doped SnO 2 catalyst support prepared via simplified chemical method. • Interactive nature of the Ru-doped SnO 2 with Pt/Pd confirmed. • Efficient Pt/Ru–SnO 2 catalyst towards the EOR. • Performance and stability suggest the use of novel catalysts in the DAFC. [ABSTRACT FROM AUTHOR]

Novel macromolecular graft copolymers were synthesized by reaction of the hydroxyl groups of the microbial polysaccharide levan, produced using Bacillus licheniformis , with polystyrene (Lev-g-PS). Synthesis was performed by the free radical reaction using potassium persulfate (PPS) as initiator. The prepared copolymer was characterized by FTIR, SEM, TG/DTA, XRD and 13 C NMR. The influence of the different conditions (reaction temperature, air or nitrogen atmosphere, reaction time, type of amines and ascorbic acid (AA) concentration) on the grafting reaction was investigated. Results showed that maximum percentage of grafting (58.1%) was achieved at a reaction temperature 70 °C, in a nitrogen atmosphere and using dimethylethanolamine (DMEA) as the amine activator. On the basis of the obtained results, the likely reaction mechanism was proposed. Synthesized copolymers have better thermal stability in comparison with their initial components. Copolymers such as Lev-g-PS could potentially have many applications, such as compatibilizers and material for membranes. [ABSTRACT FROM AUTHOR]

This manuscript presents contribution on the improved efficiency of the alkaline electrolytic production of hydrogen by in situ adding activating compounds directly into the electrolyte during the electrolytic process. New electrode material, ternary system, Ni–Cu–Mo, was applied as activating compound i.e. ionic activator. The energy requirements per mass unit of hydrogen produced is reduced for more than 10%, compared to non-activated, 30 wt. % KOH electrolyte system. Energy saving is higher at higher temperatures and at higher current densities. During the electrolytic process, the ionic activators develop nanosized porous structure deposits on the surface of the Ni electrode. Presented results point out a strong possibility of the usage of ternary ionic activators in industrial applications. [ABSTRACT FROM AUTHOR]

Abstract: In this study, different Ni–W coatings, obtained by cheap and technologically simple electrodeposition method, were examined as potential electrocatalysts for the hydrogen evolution reaction (HER). All electrodepositions were done on a Ni mesh substrate from ammoniacal-citrate bath containing different concentrations of Na2WO4. The influence of deposition parameters, such as deposition current density, pH and composition of ammoniacal-citrate bath on electrocatalytic activity of obtained Ni–W coatings toward HER was examined by polarization curve measurements in 6 M KOH at room temperature. The morphology and tungsten content of the Ni–W coatings were investigated by means of SEM and EDS analysis. All investigated electrodes have shown high electrocatalytic activity for the HER. The samples obtained at higher deposition current densities had the lowest overvoltage for the HER. It has been shown that the plating bath pH value is very important parameter in obtaining active coatings. Results of the analysis of polarization curves, morphology of deposited Ni–W coatings and the content of tungsten in the coatings, indicate that the surface roughness of the coatings is responsible for their catalytic activity towards HER. [Copyright &y& Elsevier]