Electrodeposited palladium as efficient electrocatalyst for hydrazine and methanol electro-oxidation and detection

Electrodeposited palladium was used as an electrocatalyst for electrochemical oxidation of hydrazine and methanol and the development of a sensitive platform for their detection. The electrochemical behavior of the electrode was evaluated by cyclic voltammetry (CV) while electroanalytical properties were determined by means of differential pulse voltammetry (DPV). The electrodeposited Pd catalyst exhibited good electrocatalytic activity towards the oxidation of hydrazine in neutral solution and methanol oxidation in alkaline solution. Under optimized DPV conditions, the electrodeposited Pd electrode shows good sensing capability in hydrazine and methanol detection

Correlation between Formic Acid Oxidation and Oxide Species on Pt(Bi)/GC and Pt/GC Electrode through the Effect of Forward Potential Scan Limit

Following earlier works from our laboratory, further experiments on electrochemical behavior in formic acid oxidation at electrodeposited Pt(Bi)/GC and Pt/GC electrode were performed in order to examine the effect of successive increase of the forward potential scan limit. Correlation between formic acid oxidation and oxide species on Pt(Bi)/GC electrode with increases of forward potential scan limit is based on the dependency of the backward peak potential from backward peak current. The obtained dependency reveals Bi influence for the scan limits up to 0.8 V. Since the Pt(Bi)/GC electrode is composed of Bi core occluded by Pt and Bi-oxide surface layer, the observed behavior is explained through the influence of surface metal oxide on easier formation of OHad species. Nevertheless, the influence of electronic modification of Pt surface atoms by underlying Bi is present and leads to the stronger adsorption of OH on Pt. At higher forward potential scan limits (from 0.8 V), Pt has a dominant role in HCOOH oxidation

Electrochemical behaviour of electrodeposited Pd and PdNi coatings for the ethanol oxidation reaction in alkaline solution

Electrodeposited Pd and PdNi coating samples were tested for ethanol oxidation reaction (EOR) in alkaline solution using cyclic voltammetry (CV), chronoamperometric (CA) and quasi steady-state measurements. All alloy samples showed higher current densities for the EOR than pure Pd coating. The current density increased with increasing the amount of Pd in the PdNi coating and the most active one was found to be Pd0.74Ni0.26. Based on CA measurements a pseudo-steady state is achieved after 1500 s showing that Pd0.74Ni0.26 is more efficient and poisoning more tolerant than other investigated coatings. Upon the end of the current-time transient, the investigated catalysts were subjected to the potential cycling showing the ability to recover activity loss implying the surface composition stability of binary coatings

Impact of deposition conditions on the electrocatalytic performances of Sn-Pd catalysts in ethanol oxidation reaction

We are reporting the electrochemical behavior of bimetallic Sn-Pd catalysts in ethanol oxidation reaction (EOR). Sn-Pd catalysts were prepared by two step electrodeposition technique whereby by regulating deposition conditions various forms of Sn dendrites and different atomic ratios of Sn:Pd were achieved. The electrocatalytic activity of Sn-Pd catalysts were evaluated for EOR in alkaline solution using cyclic voltammetry (CV) and chronoamperometric (CA) measurements. The highest activity and anti-poisoning ability exhibited Sn0.67-Pd0.33 catalyst due to the better utilization of Pd. At Sn0.67-Pd0.33 catalyst Sn better contribute Pd to oxidize chemisorbed species by providing adsorbed OH- species, thereby enabling well synergy of Sn with PdU ovom radu se bavimo ispitivanjem elektrohemijskog ponašanja Sn-Pd katalizatora u reakciji oksidacije etanola (ROE). Sn-Pd katalizatori su dobijeni dvostepenim elektrohemijskim taloženjem, pri čemu se regulisanjem uslova taloženja dobijaju različite forme Sn dendrita i različiti atomski odnosi Sn:Pd. Elektrohemijska aktivnost Sn-Pd katalizatora je procenjena u ROE u alkalnoj sredini korišćenjem ciklične voltametrije (CV) i hronoamperometrijskim merenjima. Najveću aktivnost i toleranciju prema otrovima je pokazao Sn0.67-Pd0.33 katalizator zbog boljeg iskorišćenja Pd. Primećeno je da kod Sn0.67-Pd0.33 katalizatora Sn bolje doprinosi oksidaciji hemisorbovanih čestica na Pd obezbeđivanjem OH- čestica, omogućujući tako dobru sinergiju Sn sa Pd

Correlation Between Morphology and Structure of Galvanostatically Electrodeposited Tin Dendrites

Tin dendrites found wide application in various industries.1 They can be obtained by both non-electrochemical and electrochemical methods of synthesis. In this study, they were produced by a galvanostatic regime of electrolysis from alkaline hydroxide solution at a current density of –3 mA cm–2 , 1.5 times larger than the limiting diffusion current density, with an amount of the electricity of 200 and 400 mC. In the dependence of an amount of the passed electricity, Sn dendrites of various morphology and crystal orientation were obtained: the fern-like dendrites predominantly oriented in (220), (440) crystal planes are obtained with 200 mC and the spear-like and the dendrites with prismatic branches showing the strong (200),(400) preferred orientationwere obtained with 400 mC. The strong correlation between morphology and structure of Sn dendrites is established and it can be explained by analysis of chronopotentiometry response obtained at the given current density and by morphological and structural analyses of Sn dendrites obtained by a potentiostatic regime at cathodic potentials corresponding to values attained after the passed amount of the electricity of 200 and 400 mC. The chronopotentiometry response after spent 200 mC was dominantly in the (–1600 – 1740) mV vs. Ag/AgCl range, and the fern-like dendrites with the strong (220), (440) preferred orientation were obtained in this potential range. After spent 400 mC, the chronopotentiometry response was about –1200 mV vs. Ag/AgCl, and the spear-like and the dendrites with prismatic branches with the strong (200),(400) preferred orientationwere obtained at this cathodic potential

Correlation Between Morphology and Structure of Galvanostatically Electrodeposited Tin Dendrites

Tin dendrites found wide application in various industries.1 They can be obtained by both non-electrochemical and electrochemical methods of synthesis. In this study, they were produced by a galvanostatic regime of electrolysis from alkaline hydroxide solution at a current density of –3 mA cm–2, 1.5 times larger than the limiting diffusion current density, with an amount of the electricity of 200 and 400 mC. In the dependence of an amount of the passed electricity, Sn dendrites of various morphology and crystal orientation were obtained: the fern-like dendrites predominantly oriented in (220), (440) crystal planes are obtained with 200 mC and the spear-like and the dendrites with prismatic branches showing the strong (200),(400) preferred orientationwere obtained with 400 mC. The strong correlation between morphology and structure of Sn dendrites is established and it can be explained by analysis of chronopotentiometry response obtained at the given current density and by morphological and structural analyses of Sn dendrites obtained by a potentiostatic regime at cathodic potentials corresponding to values attained after the passed amount of the electricity of 200 and 400 mC. The chronopotentiometry response after spent 200 mC was dominantly in the (–1600 –1740) mV vs. Ag/AgCl range, and the fern-like dendrites with the strong (220), (440) preferred orientation were obtained in this potential range. After spent 400 mC, the chronopotentiometry response was about –1200 mV vs. Ag/AgCl, and the spear-like and the dendrites with prismatic branches with the strong (200),(400) preferred orientationwere obtained at this cathodic potential

Phenomena of Nucleation and Growth of Tin Dendrites from the Alkaline Solution

The processes of nucleation and growth of tin dendrites from the alkaline hydroxide solution have been investigated. Nucleation of tin was examined by chronoamperometry at the cathodic potentials which belonged to various positions at the polarization curve. The morphology of potentiostatically electrodeposited tin dendrites with various amounts of the electricity was characterized by scanning electron microscopy (SEM) technique. Depending on the cathodic potential applied for Sn electrodeposition, the following forms of Sn dendrites were obtained: the needle-like, the spear-like and the fern-like dendrites of various degree of ramification. Combining Sharifker and Hills (SH) model for a determination of nucleation type and results of morphological analysis of Sn dendrites, it is concluded that nucleation of Sn from the alkaline hydroxide solution follows the progressive type of nucleation.Analizirani su procesi nukleacije i rasta dendrita kalaja iz alkalnog hidroksilnog rastvora. Nukleacija kalaja je bila ispitana hronoamperometrijom na katodnim potencijalima koji su pripadali različitim pozicijama na polarizacionoj krivoj. Morfologija potenciostatski elektrohemijski istaloženih dendrita kalaja sa različitim količinama elektriciteta je bila okarakterisana tehnikom skenirajuće elektronske mikroskopije (SEM). U zavisnosti od katodnog potencijala primenjenog za elektrohemijsko taloženje kalaja, formirani su sledeći oblici dendrita kalaja: igličasti, dendriti nalik koplju i dendriti nalik paprati različitog stepena razgranatosti. Kombinovanjem Šarifkerovog i Hilsovog (SH) modela za određivanje tipa nukleacije i rezultata morfološke analize dendrita kalaja, zaključeno je da nukleacija kalaja iz alkalnog hidroksilnog rastvora sledi progresivni tip nukleacije

Uticaj parametra i režima elektrohemijskog taloženja na morfologiju i strukturu dendrita kalaja

Tin dendrites were synthesized via electrochemical route from the alkaline electrolyte applying both potentiostatic and galvanostatic regimes of the electrodeposition. Various both cathodic potentials and amounts of the passed electricity were used for Sn electrodeposition in the potentiostatic regime. Morphology and structure of synthesized tin dendritic particles were characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD) techniques, respectively. Depending on the applied cathodic potential, morphology of tin dendrites changed from the needle-like and the spear-like to very ramified dendrites of various shape. The branchy Sn dendrites were of two dimensional (2D) shape constructed from stalk and branches developed from it (primary (P) branches), classifying them into 2D(P) type according to Wranglen`s definition of a dendrite. The XRD analysis of produced tin particles showed that the needle-like and the spear-like dendrites represented monocrystals (200) orientation, while Sn crystallites in the potenciostatically obtained 2D(P) dendrites were predominately oriented in (440) plane. Morphology of tin particles was also correlated with polarization characteristics for this system, confirming belonging tin to the group of the normal metals, characterized by the high values of the exchange current density and overpotential for hydrogen evolution reaction, and by the low melting point.Dendriti kalaja su bili sintetizovani elektrohemijskim putem iz alkalnog elektrolita primenjujući i potenciostatski i galvanostatski režim elektrohemijskog taloženja. Elektrohemijsko taloženje kalaja u potenciostatskom režimu je vršeno na različitim katodnim potencijalima i sa različitim količinama naelektrisanja. Morfologija i struktura sintetizovanih dendritičnih čestica kalaja su okarakterisane tehnikom skenirajuće elektronske mikroskopije (SEM) i rentgensko difrakcionom analizom. U zavisnosti od primenjenog katodnog potencijala, morfologija dendrita kalaja se menjala od igličastih i dendrita nalik koplju do veoma razgranatih dendrita. Veoma razgranati kalajni dendriti su bili dvodimenzionalnog (2D) oblika izgrađeni od stabla i grana razvijenih iz stabla (primarne (P) grane), klasifikujući ih u 2D(P) tip prema Vranglenovoj definiciji dendrita. Rentgensko-difrakciona analiza je pokazala da igličasti i dendriti nalik koplju su predstavljali monokristale (200) orijentacije, dok su kristaliti kalaja u potenciostatski dobijenim 2D(P) dendritima bili predominantno orijentisani u (440) ravni. Morfologija čestica kalaja je bila takođe korelisana sa polarizacionim arakteristikama za ovaj sistem, potvrđujući pripadnost kalaja grupi normalnih metala okarakterisanih visokim vrednostima gustine struje izmene i prenapetosti za reakciju izdvajanja vodonika, i niskom tačkom topljenja

Facile Synthesis of Sn-Pd Catalysts With High Performances For Ethanol Electro-Oxidation In Alkaline Medium

Nanostructured materials present unique properties as electrocatalysts for various industrial needs such as electrochemical energy conversion and storage. Aiming to enhance the electrocatalytic properties of Pd towards the electrochemical oxidation of ethanol, we used the electrodeposited Sn dendrites as a sub-layer for Pd. We tested the resulting Sn-Pd electrocatalysts for ethanol oxidation reaction (EOR). It was obtained that different morphological characteristics of Sn contribute to and determine Pd electrochemical behavior in EOR. By varying the amount of Sn loading prepared in the potentiostatic regime and keeping constant Pd loading, a series of Sn-Pd electrocatalysts with various ratios of Sn and Pd were synthesized and among them, Sn0.6-Pd0.4 showed to be the most active and poisoning tolerant catalyst in EOR. It was pointed out that optimization of composition and morphology assures well synergy of Sn with Pd towards EOR and at the same time demonstrates the guide for the design of novel materials with specific properties. Therefore Sn-Pd catalysts have emerged as a suitable and promising anode material for direct alcohol fuel cells

Nukleacija i rast dendrita kalaja iz alkalnog elektrolita

Procesi nukleacije i rasta dendrita kalaja iz alkalnog hidroksidnog elektrolita su istraženi hronoamperometrijom i skenirajućom elektronskom mikroskopskom (SEM) analizom taloga potenciostatski elektrohemijski istaloženih na selektivnim katodnim potencijalima. Za određivanje tipa nukleacije korišćen je model Šarifkera i Hilsa (SH) zasnovan na trodimenzionalnoj nukleaciji sa difuziono kontrolisanim rastom. Bez obzira na primenjeni katodni potencijal, dobijene bezdimenzionalne zavisnosti su bile niže od teorijskih predviđanja za progresivni tip nukleacije. Sa druge strane, morfologija dendrita kalaja je snažno zavisila od primenjenog katodnog potencijala, te igličasti ili dendriti nalik paprati su bili formirani potenciostatskim režimom elektrohemijskog taloženja. Na osnovu morfološke analize Sn dendrita elektrohemijski istaloženih različitim količinama elektriciteta, zaključeno je da nukleacija Sn iz ispitivanog elektrolita ipak sledi progresivni tip, i da se odstupanje od teorijskih predviđanja za ovaj tip može pripisati upotrebi kompleksnog elektrolita za elektrohemijsko taloženje kalaja.The processes of nucleation and growth of tin dendrites from alkaline hydroxide electrolyte have been investigated by chronoamperometry and by the scanning electron microscopic (SEM) analysis of the deposits potentiostatically electrodeposited at the selected cathodic potentials. The Scharifker and Hills (SH) model based on three dimensional nucleation with diffusion controlled growth was used for a determination of a nucleation type. Irrespective of the applied cathodic potential, the obtained dimensionless dependencies were lower than the theoretical predictions for the progressive type of nucleation. On the other hand, morphology of Sn dendrites strongly depended on the applied cathodic potential, and either the needle-like or the fern-like dendrites were formed by the potentiostatic regime of electrodeposition. On the basis of the morphological analysis of Sn dendrites electrodeposited with various amounts of the electricity, it is concluded that nucleation of Sn from the examined electrolyte still follows the progressive type, and that the deviation of the theoretical predictions for this type can be attributed to use of complex electrolyte for Sn electrodeposition