Amount Of Pt Particles Research Articles

Pt-N Co-Modified TiO2 Nanotube Electrode Photoelectrocatalytic Degradation of Oxytetracycline in Simulated Wastewater.

Using photodeposition and plasma, Pt-N co-modified TiO2 nanotube electrodes were created. Several techniques, such as SEM, XRD, UV-VIS-DRS, XPS, and PL, were used to analyze the electrode shape, crystalline structure, light absorption range, elemental composition, and photogenerated carrier recombination efficiency. Using the electrochemical workstation, EIS and I-t were utilized to examine the electrochemical characteristics. The results indicated that the diameter of the TiO2 nanotube tubes was around 90 nm, and that the photodeposition duration affected the amount of Pt particles deposited. The deposited Pt particles efficiently reduced the photogenerated carrier complexation rate of the N-TiO2 nanotube electrode, contributing to the separation of electron-hole pairs and light utilization. Electrochemical studies indicated that Pt-N co-modified TiO2 increased the electrode's oxidation and electrical conductivity, as well as its photoelectrocatalytic capacity. Oxytetracycline degradation in simulated wastewater by a Pt-N co-modified TiO2 nanotube electrode revealed the exceptional PEC activity, and the oxytetracycline degradation processes followed primary kinetics. •O2- and •OH played a significant role in the photoelectrocatalytic degradation of oxytetracycline, resulting in a novel method for oxytetracycline degradation.

A facile approach for fabrication of three-dimensional platinum-nanoporous gold film and its application for sensitive detection of microRNA-126 combining with catalytic hairpin assembly reaction

MicroRNAs (miRNAs) as important biomarkers are closely related to cancers. Herein, a easy-facilitative nanocomposite which consists of Pt nanoparticles (PtNPs) and nanoporous gold (NPG) structure has been successfully prepared on Au electrode through a facile two-step square wave voltammetry (SWV) combining with electrodeposition method. Scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS), and cyclic voltammetry (CV) were used for microscopic analysis and electrochemical studies of the PtNPs/NPG modified electrode. Combined with the well-designed catalytic hairpin assembly (CHA) amplification strategy, the small amount of Pt particles presented over the NPG film electrode substantially improved the electrocatalytic activity in the determination of microRNA-126 (miRNA-126), and a significant increase of amperometric current response accompanied with low background signal could be monitored at PtNPs/NPG electrode compared to those of bare Au and NPG electrodes. Under optimal conditions, a wide linear range of 0.5–500 pM for the amperometric assay of miRNA-126 was achieved along with a limit of detection (S/N = 3) of 0.17 pM. We further applied this assay to detect target miRNA in the total RNA extract of H1975 cells. Therefore, the proposed biosensing platform exhibits good analytical performance such as facile, ultrasensitive, low-cost, and high anti-interference capability, which promises to be a potential and beneficial tool for biomedical research and early clinical diagnosis of cancers through detection of multiple miRNA biomarkers.

A novel approach for one-step fabrication of platinum-nanoporous gold film via oxygen bubble template with enhanced electrochemical activity

A simple method was proposed to deposit a platinum-nanoporous gold film (Pt-NPGF) on a Au surface in absence of binary alloys, chemical reducing agents, and stabilizers using the in-situ generated oxygen bubble template approach. FE-SEM, EDX, and cyclic voltammetry were used for microscopic analysis and electrochemical studies. The small amount of Pt particles presented over the NPGF substantially improved the electrocatalytic activity e.g. for methanol oxidation, as an enhanced current response with low CO poisoning was observed at the Pt-NPGF electrode compared to that of bare Au, Pt, and NPGF electrodes in alkaline solution. Moreover, diffusion-limiting plateau currents corresponding to both H2O2 oxidation and reduction processes were noticed in PBS solution at a Pt-NPGF microelectrode.

Rod-shaped CeO2 intercalated Graphene for supporting Pt composite as Anode catalysts for DMFCs

A designed rod-shaped CeO2 (NRCeO2) was successfully synthesized using an in situ growth method on graphene sheets (GNs), which act as a spacer to prevent graphene from stacking. When graphene sheets with rod-shaped CeO2 and embellished with Pt nanoparticles are stacked on one another, a three-dimensional (3D) layer-by-layer Pt-NRCeO2/GNs composite structure is created. For the TEM and SEM characterization, the 3D structure has been confirmed. In the electrochemical tests, the as-designed 3D Pt-NRCeO2/GNs catalyst shows the highest ESA value (72.6 m2 g−1) and largest catalytic current density (498 mA mg−1) for methanol oxidation compared with other catalysts. Because of the effect of the rod-shaped CeO2, which acts as a spacer to prevent graphene stacking, a large amount of Pt particles are exposed to the electrolyte solution. The designed 3D Pt-NRCeO2/GNs composite structure is an efficient method to improve the electrocatalytic performance.

Effects of Water Structure on Proton Transport in Nafion Thin Films with Molecular Dynamics Simulations

Polymer electrolyte fuel cell (PEFC) is expected to play important roles for next generation power systems in terms of high efficiency and low environmental burden and capability for emergency use, but there are still many hurdles to be largely commercialized. One of them results from problems in catalyst layers (CL). What required for CL is, for example, reducing the amount of Pt particles with keeping high current density. To accomplish this, knowledge about optimum structures of CL based on material transport properties is needed because there is a strong correlation between current density and transport properties. Although there are many reports about material transport properties in the polymer electrolyte membrane (PEM), it is predicted that material transport properties in CL show some unique characteristics because of effects of interfaces in CL. It means that the knowledge obtained from PEM should not be applied to CL. In addition, the researches about CL have been tried by means of experiments and simulations, but especially the transport properties have not been clarified yet. There are nanoscopic structures in Nafion thin films and it is hard to capture the transport phenomena in such a small area by experiments and macroscopic simulations. In this study, we analyze proton transport properties in the cathode CL using molecular dynamics simulations, focusing on the dependences of the diffusion coefficient on water content. We consider the proton transport mechanism as a combination of the Vehicular mechanism and the Grotthuss mechanism. The Grotthuss mechanism is represented using empirical valence bond methods. It has been shown by previous researches in PEM that the Grotthuss mechanism is a dominant factor for proton diffusion in relatively high water contents. Thus, it is essential to consider the Grotthuss mechanism for analysis of proton transport in CL as well. The system consists of graphite surface and Nafion thin films. Pt particles are neglected because of a restriction of calculation cost. In PEM analysis, the diffusion coefficient of protons increases with increasing water contents. First, we report whether the same trend as observed in PEM can be seen in CL and the correlation between diffusibility and structures. Next, unique characteristics of proton transport properties in CL compared to the PEM analysis are reported. They are evaluated in terms of mass distribution of the thin films and solvent molecules. From this analysis, it is found that the diffusibility is not much affected by surface because of a lack of solvent molecules on surface, which is attributed to the hydrophobic properties of graphite.

Effect of functionalization for carbon molecular sieve (CMS) synthesized using zeolite template on the incorporation of Pt nanoparticle and performance of the electrodes in PEMFC

Well-ordered microporous carbon molecular sieve (CMS) with high surface area was successfully synthesized using zeolite Y as a template for the application in polymer electrolyte fuel cells (PEMFC). CMS is noncovalently functionalized with poly (diallyldimethylammonium chloride, PDDA) and loaded with Pt nanoparticles by reducing Pt precursor (H 2PtCl 6) in ethylene glycol via polyol method. X-ray photoelectron spectroscopy (XPS) analysis indicates that positively charged PDDA has been irreversibly adsorbed onto the hydrophobic surface of CMS via the π–π interaction between the unsaturated C C contaminants in PDDA chains. TEM images clearly show that the size of Pt nanoparticles deposited on CMS depends on the amount of PDDA and a significant amount of Pt particles has been anchored to the PDDA-functionalized CMS. The BET surface areas of Pt-PDDA-CMSs are inversely proportional to the amount of PDDA. The stability test for Pt-PDDA-CMS was conducted through repeated potential cycling experiment up to 1200 repeated cycles and exhibited much better stability compared to Pt-CMS and commercial Pt/C. It is seen that the higher the PDDA incorporation is, the larger the electrochemical active surface area is after 1200 repeated cycles of operation.

Preparation of the visible light responsive N3−-doped WO3 photocatalyst by a thermal decomposition of ammonium paratungstate

The nitrogen doped WO3 (N-WO3) photocatalyst was successfully prepared by a thermal decomposition of an ammonium paratungstate [(NH4)10W12O41·5H2O] containing NH4+ ions as a nitrogen source. The N-WO3 prepared at 673–873K efficiently absorbed visible light in longer wavelength regions as compared to a commercial N-free WO3. Although small amount of Pt particles must be deposited on the catalyst surfaces, the N-WO3 photocatalysts were found to decompose gaseous methanol into CO2 and H2O under visible or solar light irradiations. As well as, the Pt particles on the N-WO3 surfaces to enhance the photocatalytic activity showed an oxidation catalysis property at low temperatures of 323–333K. These results suggest that the N-WO3 deposited with Pt particles can effectively utilize the sunlight as light and/or heat sources.

Metal-Dispersed Polyaniline Electrodes for the Anodes of the Direct Ethanol Fuel Cell

To develop better and less expensive electrocatalysts for the oxidation of ethanol in direct ethanol fuel cells, several combinations of a conductive polymer polyaniline, dispersed Pt particles and pre-dispersed metal particles, such as Sn and Fe, were examined. The electrocatalytic activity of the Pt particles was remarkably enhanced when the particles were dispersed on PANI films. The activity strongly depended on the morphology and the electrical conductivity of the five PANI films with different dopant anions: SO42-, NO3- and Cl-. The highest activity was achieved for the SO42--doped PANI film. To reduce the dispersed amount of the expensive Pt particles, inexpensive base metal particles were pre-dispersed on the PANI film, and the Pt particles were then dispersed on the film. The highest activity was obtained with Sn particles. This meant that utilizing dispersed Sn particles could reduce the dispersed amount of the Pt particles needed.

Dispersed platinum and tin polyaniline film electrodes for the anodes of the direct methanol fuel cell

To develop better and cheaper electrocatalysts for the oxidation of methanol in direct methanol fuel cells, several combinations of a conductive polymer polyaniline (PANI) and dispersed metal particles such as Pt and Sn were examined. The anodic current for the methanol oxidation (iMeOH) showing the electrocatalytic activity of Pt particles was remarkably enhanced when the particles were dispersed on PANI films that should provide higher surface areas for the dispersed particles. The activity strongly depended on the morphology and the electric conductivity of the PANI films electropolymerized in five different acid solutions: H2SO4, HNO3, HClO4, HBF4, and HCl. The highest activity was achieved using the dispersed Pt particle on PANI film electropolymerized from H2SO4 polymerizing solution. In order to reduce the dispersed amount of the expensive Pt particles, other metal particles were pre-dispersed on the PANI film prepared from the H2SO4 polymerizing solution, and then Pt particles were dispersed on the film. Among the pre-dispersed metal particles attempted here (Sn, Cu, Cr, Ni, In, Co, Sb, Bi, Pb, and Mn), the highest activity was obtained with Sn particles. When the ratio of dispersed Pt to Sn particles ranges from 32:68 to 100:0, iMeOH is higher than that measured with the dispersed Pt particle on PANI films without the Sn particles. This means that the dispersed amount of the Pt particles could be reduced by utilizing dispersed Sn particles.

Electrocatalytic properties and electrochemical stability of polyaniline and polyaniline modified with platinum nanoparticles in formaldehyde medium

We report the electro-oxidation of formaldehyde on polyaniline films modified with Pt nanoparticles (PANI-Pt films) in an aqueous sulfuric acid solution. The electrodeposition of Pt particles on the PANI matrix was found to promote a mass loss of the film, with a similar effect occurring after cycling the PANI films in the acidic medium containing formaldehyde. However, despite the electrochemical instability of PANI-Pt films, on films containing larger amounts of incorporated Pt particles, the oxidation of formaldehyde produces adsorbed CO species (CO ads) at a lower positive potential than on bulk Pt. Our findings also indicate that electro-oxidation of CO ads on the PANI-Pt film surface depends not only on the thickness of PANI film but also on the amount of Pt particles incorporated into the PANI matrix.

The effect of platinum loading in the self-humidifying polymer electrolyte membrane on water uptake

The effect of Pt loading in the self-humidifying polymer electrolyte membrane (PEM) for polymer electrolyte membrane fuel cell (PEMFC) on the water uptake was investigated. The self-humidifying membrane was composed of two membranes made of perfluorosulfonylfluoride copolymer resin and fine Pt particles lying between them coated by a sputtering method. The membrane electrode assembly (MEA) was made using the decal method. The optimum amount of Pt particles embedded in the membrane for the self-humidification PEMFC was determined to be about 0.15 mg/cm 2, based upon the measurements of single cell performance characteristics and resistance.

Performance Evaluation of Platinum Dispersed Self-humidifying Polymer Electrolyte Membrane Prepared by Using RF Magnetron Sputter

The performance evaluation on Pt loading in the self-humidifying polymer electrolyte membrane for Polymer Electrolyte Mem Brane Fuel Cell(PEMFC) was investigated by using single cell test and measurement of membrane resistance. The self-humidifying membrane comprised two membranes made of perfluorosulfonylfluroride copolymer resin and fine Pt particles lying between them, coated by sputtering. From the results of performance characteristics of self-humidifying membrane cell with different Pt loading, a single cell using self-humidifying membrane with 0.15 mg/㎠ Pt loading showed better performance than that with the others over entire current density. Also, a single cell with 0.15 mg/㎠ Pt loading had a lower resistance value than the other cells under externally nonhumidifying condition. It is indicated that the water produced in the membrane cell with 0.15 mg/㎠ Pt loading showed a higher provision to maintain ionic conductivity of the membrane than the other cells. The optimum amount of Pt particles embedded in the membrane for self-humidifying PEMFC was determined to be about 0.15 mg/㎠.