Electrodeposition Of Pt Research Articles

Amperometric Oxygen Sensor Based on a Platinum Nanoparticle-Modified Polycrystalline Boron Doped Diamond Disk Electrode

Pt nanoparticle (NP)-modified polycrystalline boron-doped diamond (pBDD) disk electrodes have been fabricated and employed as amperometric sensors for the determination of dissolved oxygen concentration in aqueous solution. pBDD columns were cut using laser micromachining techniques and sealed in glass, in order to make disk electrodes which were then characterized electrochemically. Electrodeposition of Pt onto the diamond electrodes was optimized so as to give the maximum oxygen reduction peak current with the lowest background signal. Pt NPs, >0-10 nm diameter, were found to deposit randomly across the pBDD electrode, with no preference for grain boundaries. The more conductive grains were found to promote the formation of smaller nanoparticles at higher density. With the use of potential step chronoamperometry, in which the potential was stepped to a diffusion-limited value, a four electron oxygen reduction process was found to occur at the Pt NP-modified pBDD electrode. Furthermore the chronoamperometric response scaled linearly with dissolved oxygen concentration, varied by changing the oxygen/nitrogen ratio of gas flowed into solution. The sensor was used to detect dissolved oxygen concentrations with high precision over the pH range 4-10.

Electrodeposition of Platinum on Carbon Black for Fuel Cell Application

The electrodeposition of Pt is carried out on carbon black, from a solution of hexachloroplatinic acid, using cyclic voltammetry and pulse deposition. The substrate is previously submitted to an activation process, consisting in the formation of a hydrophilic overlayer. SEM and TEM images show that surface C black particles are totally or partially covered, depending on electrodeposition conditions. Cross section analysis shows that the deposit occurs to a depth of less than 5 µm. Results from single cell testing are shown.

Synthesis and high catalytic properties of mesoporous Pt nanowire array by novel conjunct template method

A novel conjunct template method for fabricating mesoporous Pt nanowire array through direct current (DC) electrodeposition of Pt into the pores of anodic aluminum oxide (AAO) template on Ti/Si substrate from hexagonal structured lyotropic liquid crystalline phase is demonstrated in this paper. The morphology and structure of as-prepared Pt nanowire array are characterized by field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM) and X-ray diffraction (XRD). The electrocatalytic properties of Pt nanowire array for methanol are also investigated in detail. The results indicate that Pt nanowire array has the unique mesoporous structure of approximate 40–50 nm in diameter, which resulted in the high surface area and greatly improved electrocatalytic activity for methanol. The mesoporous Pt nanowire array synthesized by the new conjunct template method has a very promising application in portable fuel cell power sources.

Carbon Fiber (CF) Supported Single-Particle Pt Electrodes Obtained from Pulsed Electrodeposition of Pt Followed by Electrophoretic Paint Deposition

not Available.

Preparation of Pt–Co alloy catalysts by electrodeposition for oxygen reduction in PEMFC

Direct current (DC) and pulse current (PC) electrodeposition of Pt–Co alloy onto pretreated electrodes has been conducted to fabricate catalyst electrodes for oxygen reduction reaction (ORR) in proton exchange membrane fuel cells (PEMFC). The effect of plating mode and pulse plating parameters on the Pt–Co alloy catalyst structure, composition and electroactivity for the ORR in PEMFC has been investigated. The electrodeposited Pt–Co alloy catalyst indicates higher electrocatalytic activity towards the ORR than the electrodeposited Pt catalyst. The activity of the electrodeposited Pt–Co catalysts is further improved by applying the current in a pulse waveform pattern. The electrodeposition mode and the pulse plating parameters do not have the significant effect on the Pt:Co composition of deposited catalysts, but show the substantial effect on the deposit structures produced. The Pt–Co catalysts prepared by PC electrodeposition have finer structures and contain smaller Pt–Co catalyst particles compared to that produced by DC electrodeposition. By varying the Pt concentration in deposition solution, the Pt:Co composition of the electrodeposited catalyst that exhibits the highest activity is found. The Pt–Co alloy catalyst with the Pt:Co composition of 82:18 obtained at the charge density of 2 C cm−2, the pulse current density of 200 mA cm−2, 5% duty cycle and 1 Hz was found to yield the best electrocatalytic activity towards the ORR in PEMFC.

Stabilization and Characterization of Pt Nanoparticles on HOPG

Platinum nano-catalysts are deposited, either by electrodeposition at constant potential or thermal decomposition, onto highly ordered pyrolytic graphite (HOPG). To help stabilize the nano-catalyst, the HOPG substrate is oxidized either by electrochemical methods or by ozone gas. The combination of two deposition techniques and two substrate oxidation techniques results in four different types of samples. As a point of reference, the particle morphology, activity towards oxidation of adsorbed carbon monoxide, and electrochemical stability of the four different types of samples are compared to a sample made by electrodeposition of Pt onto freshly cleaved HOPG. Of the four samples prepared, the combination of thermal reduction onto ozone oxidized HOPG was found to produce the most stable platinum nano-catalyst.

Effect of deposition sequence of platinum and ruthenium particles into nanofibrous network of polyaniline–poly(styrene sulfonic acid) on electrocatalytic oxidation of methanol

This study reports on the preparation of Pt- and Ru-based electrocatalysts through electrodeposition of Pt and Ru particles into the nanofibrous network of polyaniline (PANI)–poly(styrene sulfonic acid) (PSS). The sequence of electrodeposition of Pt and Ru particles was changed and the electrocatalysts, PANI–PSS–Pt–Ru and PANI–PSS–Ru–Pt, were obtained. Scanning electron microscopy (SEM), X-ray photoelectron microscopy (XPS), and cyclic voltammetry (CV) were employed to investigate the morphology, structural and electrochemical properties of the electrocatalysts, PANI–PSS–Pt–Ru and PANI–PSS–Ru–Pt. The distribution of Pt and Ru particles into PANI–PSS matrix was analyzed by the Auger depth profiles. The electrochemical behavior PANI–PSS–Pt–Ru and PANI–PSS–Ru –Pt and the electrocatalytic behavior toward oxidation of methanol were evaluated by cyclic voltammetry. PANI–PSS–Ru–Pt exhibited a superior electrocatalytic performance for methanol oxidation as compared to PANI–PSS–Pt–Ru.

Electrochemical preparation of a novel, effective and low cast catalytic surface for hydrogen evolution reaction

The formation of platinum nucleus on the freshly polished aluminum (Al) and anodized aluminum electrodes (Al 2O 3/Al) was studied by cyclic voltammetry. Results showed that the deposition of platinum on freshly polished aluminum from an aqueous 0.5 M phosphate buffer solution containing H 2PtCl 6 takes place rapidly through the electroreduction of dissolved Pt (IV) ions. At shorter deposition times, small particles of platinum crystals were formed on the aluminum and the surface coverage was imperfect. At longer deposition times, the size of the platinum crystals increases while their number decreases due to the coalescence and agglomeration processes. The electrodeposition of Pt on the Al electrode was conveniently carried out over the Al 2O 3/Al electrode. The electrochemical and catalytic activities of the Pt/Al and Pt/Al 2O 3/Al electrodes were studied in 0.1 M H 2SO 4 solution. In cyclic voltammetry, the two pair symmetric peaks appeared in 0.1 M H 2SO 4 solution which was attributed to the formation of strongly (H s) and weakly bounded hydrogen (H w). The occurrence of the third anodic hydrogen peak (H 3rd) was revealed at low scan rate and in high concentration of H 2SO 4. At potentials more negative than −0.3 V vs. SCE, the current is mainly due to hydrogen evolution reaction. The influence of the various parameters such as deposition method and amount of platinum, sulfuric acid concentration and medium temperature on the hydrogen evolution reaction is described. Finally the kinetic of the hydrogen evolution reaction is also discussed on the Pt/Al electrode.

Poly(2,5-dimethoxyaniline-co-2,5-diaminobenzenesulfonic acid) with cross-linking structure for platinum deposits in methanol oxidation

Cross-linking structural copolymer, poly(2,5-dimethoxyaniline-co-2,5-diaminobenzenesulphonic acid) was synthesized by electrochemical deposition of two monomer, 2,5-dimethoxyaniline, DMA and 2,5-diaminobenzenesulfonic acid, DABSA. The cross-linking structure of copolymer was characterized by scanning electron microscopy, X-ray photoelectron spectroscopy and thermogravimetric techniques. Copolymer with cross-linking structure provides more and deeper nucleation sites for the deposition of platinum (Pt) than homopolymer via electrochemical method, being certified by secondary ion mass spectrometer. Meanwhile, the existence of the SO 3H group in copolymer might also help the electrodeposition of Pt. Copolymer-Pt nanocomposite film demonstrates better activity and stability toward methanol oxidation than homopolymer-Pt.

Electrodeposition of Pt onto RuO2(110) Single-Crystal Surface

The electrodeposition of Pt on RuO2(110) from acid solutions of several Pt complexes was studied using programmed potential step or potential sweep methods. The RuO2(110) single-crystal surface was obtained by gas-phase oxidation of Ru(0001). The electrodeposition process is characterized by a large crystallization overpotential and three-dimensional growth from a Pt adlayer. The mismatch between the RuO2(110) and Pt lattices is the likely origin of that overpotential. The nucleation is instantaneous, as verified by potential step experiments. The process starts with depositing a 0.25 ML of Pt, with Pt atoms arranged in a c(2 × 2) array, which is followed by the growth of Pt islands and three-dimensional clusters as in the Stranski−Krastanov growth mode. Density functional theory calculations were used to help in elucidating atomically resolved electrochemical scanning tunneling microscopy (ECSTM) images of the initial stages of Pt deposition. A Pt adlayer on RuO2(110) has lower catalytic activity for the...

A novel method for the preparation of bi-metallic (Pt–Au) nanoparticles on boron doped diamond (BDD) substrate: application to the oxygen reduction reaction

A novel method was developed to synthesize bi-metallic nanoparticles (Au–Pt) on boron-doped diamond (BDD) substrate. This method consisted of (a) deposition of a small amount of gold (equivalent to a few monolayers) by sputtering on the BDD surface, (b) heat treatment of the obtained sample at 600 °C in air, resulting in the formation of stable nanoparticles on BDD (Au/BDD electrode), (c) electrodeposition of Pt on the Au/BDD surface occurring preferentially on the Au nanoparticles, and finally (d) heat treatment at 400 °C to enhance the interaction between Au and Pt. The ratio between Au and Pt nanoparticles can be modified by modifying the amount of electrodeposited Pt and was estimated using cyclic voltammetry. These Pt-Au/BDD composite electrodes were used to study oxygen reduction using both potential sweep (cyclic voltammetry) and hydrodynamic (turbine electrochemical cell) methods.

Selective and sensitive electrochemical detection of glucose in neutral solution using platinum–lead alloy nanoparticle/carbon nanotube nanocomposites

Electrodeposition of Pt–Pb nanoparticles (PtPbNPs) to multi-walled carbon nanotubes (MWCNTs) resulted in a stable PtPbNP/MWCNT nanocomposite with high electrocatalytic activity to glucose oxidation in either neutral or alkaline medium. More importantly, the nanocomposite electrode with a slight modification exhibited high sensitivity, high selectivity, and low detection limit in amperometric glucose sensing at physiological neutral pH (poised at a negative potential). At +0.30 V in neutral solution, the nanocomposite electrode exhibited linearity up to 11 mM of glucose with a sensitivity of 17.8 μA cm −2 mM −1 and a detection limit of 1.8 μM (S/N = 3). Electroactive ascorbic acid (0.1 mM), uric acid (0.1 mM) and fructose (0.3 mM) invoked only 23%, 14% and 9%, respectively, of the current response obtained for 3 mM glucose. At −0.15 V in neutral solution, the electrode responded linearly to glucose up to 5 mM with a detection limit of 0.16 mM (S/N = 3) and detection sensitivity of ∼18 μA cm −2 mM −1. At this negative potential, ascorbic acid, uric acid, and fructose were not electroactive, therefore, not interfering with glucose sensing. Modification of the nanocomposite electrode with Nafion coating followed by electrodeposition of a second layer of PtPbNPs on the Nafion coated PtPbNP/MWCNT nanocomposite produced a glucose sensor (poised at −0.15 V) with a lower detection limit (7.0 μM at S/N = 3) and comparable sensitivity, selectivity and linearity compared to the PtPbNP/MWCNT nanocomposite. The Nafion coating lowered the detection limit by reducing the background noise, while the second layer of PtPbNPs restored the sensitivity to the level before Nafion coating.

Preparation of low Pt loading electrodes on Nafion (Na +)-bonded carbon layer with galvanostatic pulses for PEMFC application

Low Pt loading electrodes were prepared by galvanostatic pulse electrodeposition on a Nafion-bonded carbon layer. Since the electrodeposition of Pt in aqueous solution occurred only on carbon surface with some ion conductivity (Nafion-Na +), it was possible to significantly reduce the thickness of the catalyst layer as well as the amount of Pt loading. Thus, it provided enhanced utilization efficiency of catalyst. This method consisted of a three-step procedure in the following order: deposition of Pt particles on a Nafion-bonded carbon layer, heat treatment, and a protonation process. The electrochemical surface areas of the Pt deposits were determined by cyclic voltammetry. Other physical properties of the deposit were characterized by transmission electron microscopy, X-ray diffraction measurements, and X-ray photoelectron spectroscopy. The amount of Pt deposit was determined by inductively coupled plasma-atomic emission spectroscopy. The performance of the prepared electrode was compared with conventional electrodes, which were prepared with 20 wt.% Pt/C from E-TEK. The performance of the membrane electrode assemblies employing electrodeposited electrodes (0.025 mg Pt cm −2 on the anode and 0.3 mg Pt cm −2 on the cathode) has shown competitively higher values than those of the conventional electrodes (0.3 mg Pt cm −2 on both electrodes). These results indicate a noticeable increase in the catalyst utilization due to the deposition of Pt particles taking place only in the three-phase reaction zone.

Multi-Segment Pt–RuNi Nanorods for Methanol Electro-Oxidation at Room Temperature

Three five-segment Pt-RuNi-Pt-RuNi-Pt nanorods with the same diamete, same overall rod length, and same total Pt segment length differing only in RuNi compositions, were prepared by sequential electrodeposition of Pt and RuNi (co-deposited with different Ru to Ni ratios) into the pores of commercially available anodic aluminum oxide membranes. The alternating Pt and RuNi segments could be easily differentiated in backscattered electron images from scanning electron microscopy. X-ray diffraction indicated that Pt was polycrystalline with face-centered cubic (fcc) structure; while co-deposited RuNi adopted either the Ru hexagonal close-packed (hcp) structure or the Ni fcc structure depending on the Ni content. X-ray photoelectron spectroscopic analysis showed that Pt(0) was the major surface oxidation state for Pt in the Pt segments, while Ru(0) and NiO dominated on the surface of the RuNi segments. The segmented nanorods were catalytically active in the room-temperature electro-oxidation of methanol in acidic solutions. Among the nanorods tested, the relative rates of reaction as measured by cyclic voltammetry and chronoamperometry showed that the Pt-RuNi pair sites with the Ru:Ni mass ratio of 4.24:1 had the highest catalytic activity and strongest CO-tolerance in the potential window investigated. The Pt-RuNi pair sites were also more active than the similarly produced Pt-Ru and Pt-Ni pair sites reported in a previous publication [ F. Liu , J. Y. Lee , and W. J. Zhou , Small , 2 , 121 (2006) ].

Template preparation of Pt–Ru and Pt nanowire array electrodes on a Ti/Si substrate for methanol electro-oxidation

Pt and Pt–Ru nanowire array electrodes were obtained by dc (direct current) electrodeposition of Pt and Ru into the pores of an anodic aluminum oxide (AAO) template on a Ti/Si substrate. Transmission electron microscope (TEM) examination showed all the nanowires had a uniform diameter of about 30 nm. The brush shaped Pt and Pt–Ru nanowire array electrodes could be seen clearly by scanning electron microscope. Pt and Pt–Ru nanowire array electrodes gave the X-ray diffraction pattern of a face-centered cubic (fcc) crystal structure. The electro-oxidation of methanol on these electrodes was investigated at room temperature using cyclic voltammetry. The results demonstrated that the alloy nanowire array electrode was catalytically more active than a pure platinum nanowire array electrode and the Pt–Ru nanowire array electrode may have good potential for applications in portable fuel cell power sources.

Template preparation of Pt nanowire array electrode on Ti/Si substrate for methanol electro-oxidation

Platinum (Pt) nanowire array electrode is obtained by dc electrodeposition of Pt into the pores of anodic aluminum oxide (AAO) template on Ti/Si substrate. Transmission electron microscope (TEM) examination shows all the nanowires have uniform diameter of about 30 nm. The brush shapes Pt nanowire array electrode can be seen clearly by field emission scanning electron microscope (FESEM). Pt nanowire array electrode gives the X-ray diffraction (XRD) pattern of face-centered cubic (fcc) crystal structure. The electro-oxidation of methanol on this electrode is investigated at room temperature by cyclic voltammetry. The results demonstrated that the Pt nanowire array electrode will have good potential applications in portable power sources.

The influence of electrochemical pre-treatment of B-doped diamond films on the electrodeposition of Pt

The influence of the substrate electrochemical pre-treatment in 0.5 mol L-1 H2SO4 on the Pt electrodeposition on boron-doped diamond, BDD, film electrodes was investigated. Platinum cannot be electrodeposited on a freshly prepared BDD electrode; however, potentiodynamic cycling or anodic potential steps at short times does activate the electrode. Anodic pre-treatment plays a dual role in the behavior of Pt deposition on BDD surfaces: Pt deposition is increased at short-term anodic pre-treatments, whereas at longer pre-treatment times Pt deposition was inhibited. These facts are explained in terms of wettability changes and passivation of the surface. Conversely, the oxide layer formed in these treatments increases the dispersion level of the catalyst.

Influence of Anodic Polarizations on the Electrodeposition of Metals on BDD Films

This paper accounts for the effect of anodic polarizations of BDD films in the electrodeposition of Pt an Cu. Deposition of those metals on anodized BDD surfaces gives deposits with larger specific areas. Such effect is discussed in terms of possible interactions between the Pt complex ion and the partially oxidized surface of the BDD.

Electrodeposition of Pt–Ru nanoparticles on fibrous carbon substrates in the presence of nonionic surfactant: Application for methanol oxidation

Liquid crystalline and micellar aqueous solutions of the nonionic surfactant Triton X-100 were used to direct the electrodeposition of Pt–Ru nanoparticles onto graphite felts, which were investigated as novel anodes for the direct methanol fuel cell. The effects of surfactant concentration, current density and deposition time in the preparation of these three-dimensional electrodes were studied in a factorial experiment and the electrodes were characterized by SEM and ICP-AES. Cyclic voltammetry, chronoamperometry and chronopotentiometry were carried out to assess the activity of the catalyzed felts for methanol oxidation. The presence of Triton X-100 (40–60 wt.%) coupled with an acidic plating solution were essential for the efficient co-electrodeposition of Ru in the presence of Pt to yield approximately a 1:1 Pt:Ru atomic ratio in the deposit. The highest mass specific activity, 24 A g −1 at 298 K (determined by chronoamperometry after 180 s at 0 V versus Hg/Hg 2SO 4, K 2SO 4std), was obtained for the Pt–Ru electrodeposited in the presence of 40 wt.% Triton X-100 at 60 A m −2, 298 K for 90 min. Surfactant mediated electrodeposition is a promising method for meso-scale (ca. 10–60 nm diameter) catalyst particle preparation on three-dimensional electrodes.

Stability of Pt-Catalyzed Highly Oriented Pyrolytic Graphite Against Hydrogen Peroxide in Acid Solution

Aiming at clarifying the effects of hydrogen peroxide on the degradation of catalyst in polymer electrolyte fuel cells (PEFCs), a model electrode for the catalyst was prepared by electrodeposition of Pt on highly oriented pyrolytic graphite (HOPG) and its durability against hydrogen peroxide investigated. After storage in acidic solution at room temperature, many scars were formed by oxidative etching of HOPG and Pt-particle catalysts aggregated on the surface. In contrast, no surface change was observed without hydrogen peroxide. These results showed that hydrogen peroxide significantly deteriorates the Pt/HOPG electrode, and the active surface area of the Pt particles, which was determined by cyclic voltammetry, was reduced after immersion in the solution. The influence of applied potential was also investigated, and the deterioration of the electrode was accelerated at potentials both more positive and negative than open-circuit potential (ca. ). Moreover, similar degradation phenomenon was observed when the potential was set at , at which a large amount of is formed in oxygen reduction, in -saturated -free acid solution for .