Branimir Grgur - Academia.edu (original) (raw)

Papers by Branimir Grgur

Frontiers in chemistry, Feb 1, 2024

Editorial on the Research Topic Advanced electrocatalytic materials for water electrolysis and fu... more Editorial on the Research Topic Advanced electrocatalytic materials for water electrolysis and fuel cells Advancing clean, affordable, and renewable energy is one of the key challenges of the modern world. Hydrogen has been labeled as the next-generation energy carrier able to replace fossil fuels on a large scale (Bockris, 2013). Production and utilization of green hydrogen can be achieved in electrochemical devices, namely water electrolyzers and fuel cells. The cores of these devices are catalytic materials needed for the efficient running of the occurring electrochemical reactions. Therefore, tailoring more active, durable, and costeffective electrocatalysts plays a crucial role in the pursuit of a sustainable energy cycle. Water electrolysis is a carbon-neutral technology for hydrogen production and relies on two electrochemical reactions, namely hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). Efficient electrocatalytic materials for both HER and OER are needed to make the overall energy demand for hydrogen generation as low as possible. Platinum group metals (PGMs), namely Pt and Ir, in the form of small-sized nanoparticles dispersed over high surface area supports, are state-of-the-art catalysts for HER and OER, respectively. Despite the superior performance, the usage of PGMs is hampered by their scarcity and high price; therefore, the design of catalysts based on more abundant materials is highly desirable. In this context, transition metal-based catalysts stand out due to their feasible activity combined with abundance and economic viability. Cobalt (Co) based materials are known for their ability to catalyze both water-splitting reactions. Ahmed et al. prepared a hydrated cobalt phosphate-based carbon-nanofiber-supported material (Co 3 (PO 4) 2 .8H 2 O/CNFs) using a hydrothermal approach. The presence of water in the obtained material was confirmed using several characterization techniques. Co 3 (PO 4) 2 × 8H 2 O/CNFs catalyst revealed enhanced HER activity in acid media making a significant approach to the Pt/C benchmark (the Holy Grail of hydrogen electrocatalysis). In terms of stability, the Co 3 (PO 4) 2 × 8H 2 O/CNFs catalyst revealed 24 h of fully stable operation, as confirmed by both electrochemical investigations and structural characterization. This novel composite with a flower-like structure benefited from high electrochemical surface area, high conductivity, and high exposure of edge sites in phosphates due to the vertical growth of hydrated phosphates, which altogether was found to be crucial for designing active electrode material. Photo-electrocatalysis utilizes light energy to drive electrochemical reactions onto the electrode surfaces. The synergy between light absorption and electrocatalysis holds promise

Journal of The Serbian Chemical Society, 2001

The electrochemical oxidation of carbon monoxide and the interfacial structure of the CO adlayer ... more The electrochemical oxidation of carbon monoxide and the interfacial structure of the CO adlayer (CO ads) on platinum low index single crystals, Pt(111), Pt(100) and two reconstruction of Pt(110), were examined using the rotation disk electrode method in combination with the in situ surface X-ray diffraction scattering technique. The mechanism of CO oxidation is discussed on the basis of the findings that, depending on the potential, two energetic states of CO ads exist on the platinum surfaces. Thus, at lower potentials, weakly bonded states (CO ads,w) and at higher potentials strongly bonded states (CO ads,s) are formed. The mechanism of the oxidation of hydrogen-carbon monoxide mixtures is also proposed.

Engineering Failure Analysis, Oct 1, 2020

Background : Breast feeding, the most natural way of infant feeding to satisfy nutritional, metab... more Background : Breast feeding, the most natural way of infant feeding to satisfy nutritional, metabolic and psychological needs of the baby. Objectives : To assess the knowledge of breast feeding among primi-gravida mothers attending antenatal clinic and to determine the association between socio-demographic variables with their knowledge. Materials and Methods : Hospital based cross sectional study was conducted at Antenatal clinic of Krishna Hospital and Medical Research Center, Karad district Satara. Pre-tested structured proforma used to collect information from 590 married primi gravid mothers attending anti-natal clinic during study period by utilizing personal interview method. Statistical Analysis : socio-demographic frequency percentage distribution, knowledge scoreing and statistical association was analysed by using chi-square test. Results: Out of 590 primi gravida mothers,59.66% showed fair quality of knowledge about breast feeding. knowledge about rooming in, family support for breast feeding & burping after breast feeding was 97.7%, 95.4% , 93.5% however weaning, colostrums feed, hazards of bottle feeding and prelactal food was 84%, 82.7%,75.5% and 54% respectively. Statistical association was existed between age, education, religion, socioeconomic status & occupation of respondents with their knowledge about breast feeding (? 2 =151.52, p < 0.0001*; ? 2 =211.27,p<0.0001*; ? 2 =133.91,p < 0.0001*; ? 2 =35.59,p < 0.0001* and ? 2 =131.04,p<0.0001*) respectively. Conclusion: knowledge of breast feeding among primi gravida mothers attending ANC clinic was of fair in quality.

Chemical Papers, 2017

The electrocatalytic degradation of C.I. Acid Orange 3 from simulated wastewater by indirect elec... more The electrocatalytic degradation of C.I. Acid Orange 3 from simulated wastewater by indirect electrochemical oxidation using an IrO x electrode was investigated. The effects of different operating parameters on the rate of dye decolorization were studied. The influences of mixing, electrolyte concentration, applied current, and initial dye concentration were examined. The change in dye concentration was followed by ultraviolet-visible spectroscopy, while the formation of reaction intermediates was established using high-performance liquid chromatography-mass spectrometry analysis. Ultraviolet-visible spectroscopy showed a decrease of the absorption peak at 374 nm during the electrolysis and the appearance of a new absorption maximum at 460 nm. The decolorization reaction can be followed only at 460 nm. Four intermediate products (two mono-and two dichlorinated) were detected. At the end of the study, a phytotoxicity assay was performed to determine the effectiveness of the applied method. The results showed that the applied electrochemical treatment of C.I. Acid Orange 3 leads to a decrease in phytotoxicity from 53 to 28%.

Journal of Polymer Research, 2017

Poly(aniline-co-(m-aminobenzoic acid)) was synthesized electrochemically at graphite electrode un... more Poly(aniline-co-(m-aminobenzoic acid)) was synthesized electrochemically at graphite electrode under galvanostatic conditions. Aqueous electrolyte for synthesis was consisted of HCl and different amount of aniline and m-aminobenzoic acid. The presence of the meta positioned carboxylic group in m-aminobenzoic acid influenced higher co-polymerization potential, different morphology and electrochemical behavior of copolymers compared to polyaniline. Electrochemical activity is achieved by proton exchange in neutral environment that can result in a faster charge/discharge process, which is in the case of PANI limited by slow anion exchange, making this material promising for consideration in supercapacitors and in biological system.

Langmuir, Nov 1, 1997

The underpotential deposition upd of Pb onto Pt 111 in solution containing Br was examined by cla... more The underpotential deposition upd of Pb onto Pt 111 in solution containing Br was examined by classical RRD E PtŽ111. Ž. electrochemical methods in combination with in situ surface X-ray scattering measurements. The results show that Pb upd onto Pt 111 in the presence of bromide is a competitive process with the total amount of Pb deposited at underpotential being only ca. 0.51 " 5% ML, Ž. less than the amount needed to form a close-packed monolayer, 0.63 ML 1 ML equals 1 Pb atom per Pt surface atom. Deposition of Pb adatoms is accompanied by desorption of about one-half of the bromide adsorbed on the Pt surface at higher potentials, leaving co-adsorbed bromide both in and on-top-of the adlayer. In the potential region where the ratio of co-adsorbed species is close to one Ž. Ž. Ž. E f 0 V there is the slow formation over a period of ca. 2 h of an ordered surface alloy, which has a p 2 = 2 unit cell. No other ordered structures of Pb are observed in the underpotential region.

Materials Chemistry and Physics, Feb 1, 2011

Polyaniline electrode (PANI) was formed electrochemically at graphite electrode. Electrochemical ... more Polyaniline electrode (PANI) was formed electrochemically at graphite electrode. Electrochemical polymerization was performed at constant current density of 2.0mAcm−2 from aqueous solution of 1.0moldm−3 HCl with addition of 0.25moldm−3 aniline monomer. Electrochemical characterization of the PANI electrode in chloride and chloride/citrate electrolyte was performed using cyclic voltammetry and galvanostatic measurement in order to study the influence of citrate ions on

Journal of The Electrochemical Society, 2019

The electrochemical oxidation of bromides for on-site water disinfection, on dimensionally stable... more The electrochemical oxidation of bromides for on-site water disinfection, on dimensionally stable DSA titanium coated RuO2 anode is investigated by the polarization measurements and in the semi-industrial batch reactor under constant current conditions. During electrolysis of 0.4 M bromide with the current of 5 A, the concentration of bromine, Br-2, tribromide ions, Br-3(-), hypobromous acid, HOBr, and hypobromite, BrO-, so-called equivalent bromine, Br-eq, is determined using arsenometric titration at pH similar to 9 and pH similar to 3.5. At pH similar to 9, the concentration of 0.1 M is obtained, but solutions undergo to fast decomposition. In the acidified electrolyte, the stable bromine solution with the concentration of 0.15 M after 1.75 h of electrolysis is obtained, corresponding to 14 g dm(-3) of "active bromine", a mixture of HOBr and OBr-. With typical dosing rate of active bromine for disinfection of similar to 0.5 mg per liter of water, it is suggested that investigated batch semi-industrial reactor can be used for the treatment of similar to 28.000 liters of water. Basic electrolysis parameters like, reactor voltage, temperature, pH, current efficiency, energy consumption is also determined. The reaction products are determined using thermodynamic equilibrium consideration and UV-vis spectroscopy measurements. The main loss reaction during electrolysis is considered, and appropriate analytical expressions are suggested

Journal of Alloys and Compounds, Feb 1, 2000

Electrochemical studies on LaNi Co Mn Fe metal hydride alloy 4.15 0.43 0.40 0.02 a a a b a

Research Square (Research Square), Feb 22, 2023

Primary seawater magnesium-based cell with AgCl or PbCl 2 cathodes is widely used as power source... more Primary seawater magnesium-based cell with AgCl or PbCl 2 cathodes is widely used as power sources. In this paper, we consider the cyclic galvanostatic formation of silver and lead chloride, and their electrochemical behavior for potential applications in the new concept of the seawater quasirechargeable magnesium cell. For potential cells, the voltage for Mg alloy AZ63 and AgCl is ~ 1.5 V, and for the PbCl 2 , ~ 1 V. High discharge speci c capacity, energy, and power are obtained under the very high discharge rate. Consideration of the improvements for the application in a real cell is given.

Synthetic Metals, May 1, 2023

Journal of Power Sources, Apr 1, 2021

Abstract The novel method based on the inexpensive and fast modified successive ion layer adsorpt... more Abstract The novel method based on the inexpensive and fast modified successive ion layer adsorption and reaction (SILAR) method of preparing silver chloride cathode on the carbon felt is developed. The electrochemical behavior of the silver chloride cathode in the combination with magnesium alloy AZ63 anode is investigated, as the seawater activated primary cell. Under the discharge rate of the cell of 1C, 157 mA g−1 of active materials, the voltage discharge plateau of ~1.25 V–0.9 V; specific capacity of 130 mAh g−1; specific energy of 145 mWh g−1, and specific power of 175 mW g−1 are obtained.

Corrosion Science, May 1, 2021

Abstract Platinum and nine commercial dental alloys with the contents of noble metals ranging fro... more Abstract Platinum and nine commercial dental alloys with the contents of noble metals ranging from 27 wt.% to 97.6 wt.% were investigated by the procedure described in the Standard ISO 10271:2009, Electrochemical testing was performed in an argon purged solution of 0.9% NaCl at pH = 7.2. The obtained values of the characteristic determined parameters of the alloys with different noble metal content, treating only Au, Pt, and Pd as noble, were compared with the American Dental Association (ADA) classification system. Based on the obtained results, the considered noble metal dental alloys were classified into three groups.

Journal of The Serbian Chemical Society, 2005

Fe-Mo alloys were electrodeposited from a pyrophosphate bath using a single diode rectified AC cu... more Fe-Mo alloys were electrodeposited from a pyrophosphate bath using a single diode rectified AC current. Their composition and morphology were investigated by SEM, optical microscopy and EDS, in order to determine the influence of the deposition conditions on the morphology and composition of these alloys. It was shown that the electrodeposition parameters, such as: chemical bath composition and current density, influenced both the composition of the Fe-Mo alloys and the current efficiency for their deposition, while the micro and macromorphology did not change significantly with changing conditions of alloy electrodeposition. It was found that the electrodeposited Fe-Mo alloys possessed a 0.15 V to 0.30 V lower overvoltage than mild steel for hydrogen evolution in an electrolyte commonly used in commercial chlorate production, depending on the alloy composition, i.e., the conditions of alloy electrodeposition.

Synthetic Metals, Aug 1, 2023

Synthetic Metals, Jul 1, 2011

Electrochemical polymerization of polyaniline (PANI) coating on copper electrode was performed ga... more Electrochemical polymerization of polyaniline (PANI) coating on copper electrode was performed galvanostatically in the current density range between 0.50 and 1.25mAcm−2, from aqueous solution of 0.3moldm−3 sodium benzoate and 0.2moldm−3 aniline. The corrosion behavior of PANI coated copper and copper electrode exposed to 0.5moldm−3 sodium chloride solution was investigated by potentiodynamic and electrochemical impedance spectroscopy techniques. It was observed that

Progress in Organic Coatings, Jun 1, 2018

The chemically synthesized polyaniline in the powdered form by the procedure recommended by IUPAC... more The chemically synthesized polyaniline in the powdered form by the procedure recommended by IUPAC is reprotonated using sulfamic, citric, succinic and acetic acid. The UV-vis spectroscopy is applied to estimate doping degree of the reprotonated samples. The estimated doping degrees are as follows: the polyaniline doped with sulfamic acid 0.28, with succinic acid 0.18, with citric acid 0.15 and with acetic acid 0.13. The composite coatings are prepared by mixing the alkyd based commercial paint with 5 wt.% of the reprotonated samples and painted on mild steel. Using linear polarization method, the polarization resistances of the composite and base coatings are determined in 3% NaCl. It is shown that initial oxidation state of the polyaniline determined the values of polarization resistance which decrease in the following order: R p (sulfamic) > R p (succinic) > R p (citric) > R p (acetic) ∼R p (base coating). For all composite coatings, increases in the corrosion potentials are observed during the time, while for base coating decrease. The steel samples with base and composite coatings are also immersed in 3% NaCl, after 150 h visually inspected, and by the optical microscope. It is shown that composite coatings reduce the possibility of blister formations and delamination. The appearance of the corrosion products closely follow the initial oxidation state of the polyaniline. It is suggested that such behavior could be connected with the oxygen reduction mechanism that proceed mainly via two electron path on the polyaniline particles, releasing a much smaller amount of hydroxyl ions, responsible for the delamination and blister formations.