Deposition Of Pt Nanoparticles Research Articles

High-surface area mesoporous Pt/TiO2 hollow chains for efficient formaldehyde decomposition at ambient temperature

Room-temperature catalytic decomposition of formaldehyde (HCHO) is considered as one of the most main methods for the removal of indoor HCHO due to its facile reaction conditions. Herein, high-surface area mesoporous Pt/TiO2 hollow chains were synthesized in high yield by using a simple microwave–hydrothermal route, followed by a combined NaOH-assisted NaBH4-reduction deposition of Pt nanoparticles on the as-obtained TiO2 surface. The catalytic activity for HCHO decomposition was evaluated at room temperature. The prepared Pt/TiO2 hollow chains with an optimal Pt loading of 0.5wt.% exhibited high catalytic activity and recyclability. The apparent reaction rate constant of HCHO oxidation over this catalyst was approximately 1.42×10−3ppm−1min−1, exceeding that of the commercial Degussa P25 TiO2 with equal Pt content (k=5.36×10−4ppm−1min−1) by a factor of approximately 2.65. The high catalytic activity of the Pt/TiO2 hollow chains could be mainly attributed to the hollow chain-like structure, high specific surface area, numerous mesopores, and high pore volume of TiO2 support. Consequently, the catalysts exhibited high adsorption capacity for HCHO, fast diffusion and transport of gas molecules, and good contact between gases and active sites. These characteristics enhanced the catalytic activity.

Platinum–boron doped graphene intercalated by carbon black for cathode catalyst in proton exchange membrane fuel cell

In order to enhance the electrochemical properties, especially durability and cell performance in proton exchange membrane fuel cell, electron deficient boron is doped into graphene, followed by deposition of Pt nanoparticles. Successful synthesis of Pt-boron doped graphene (Pt–B–Gr) by pyrolytic process is confirmed by X-ray diffraction, X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, Raman spectroscopy and Transmission electron microscopy analyses. Pt–B–Gr is intercalated by different amount of CB (carbon black) based on Pt–B–Gr/CBx (x = 0.0, 0.2, 0.3, 0.4) and applied to cathode in proton exchange membrane fuel cell. The ECSA (electrochemical active surface area) is increased with CB content up to 30 wt.% of Pt–B–Gr from 21.4 to 33.6 m2 g−1 beyond which it is rather slightly decreased to 29.6 m2 g−1. The ADT (accelerated durability test) is conducted where the ECSA is compared at every 400 cycles up to 1200 cycles for durability. The result exhibits that boron doping into graphene significantly enhances the durability. It might be attributed to more tight binding between Pt and B due to the electron transfer from graphene to boron. The cell performance is enhanced and it is attributed to the combined effect of B-doping and intercalation.

Pulsed electrochemical deposition of Pt NPs on polybenzimidazole-CNT hybrid electrode for high-temperature proton exchange membrane fuel cells

Nitrogen-doped CNTs, directly grown on a carbon cloth (CNT/CC) hybrid with polybenzimidazole (PBI), are utilized as hybrid electrodes in high-temperature proton exchange membrane fuel cells (HT-PEMFCs). The use of a rotation holder for pulse electrodepositing Pt nanoparticles (NPs) on a CNT electrode is developed herein. The electrochemical surface area of the Pt NPs/PBI-CNTs is approximately 161 cm2 mg−1 and the grain size is around 8–9 nm. A comparative study of 0.09 mg cm−2 Pt NPs on a PBI–CNT (Pt/PBI–CNT) electrode and 0.8 mg cm−2 Pt NPs on PBI–carbon black (Pt/PBI–CB) for reducing oxygen at the cathode was carried out. In H2/O2 HT-PEMFC single cell tests, a low Pt-loaded (0.09 mg cm−2) Pt/PBI–CNT/CC electrode outperformed a high Pt-loaded (0.8 mg cm−2) Pt/PBI–CB/CC electrode with maximum power densities of 620 mW cm−2 and 468 mW cm−2, respectively, at 160 °C. The enhanced performance is attributed to the well-controlled grain size and Pt loading of Pt NPs on the PBI-CNT in the cathode, which provide the highly active catalyst and the good electrical conductivity carbon support.

Photochemical Deposition of Highly Dispersed Pt Nanoparticles on Porous CeO2 Nanofibers for the Water‐Gas Shift Reaction

Ceria (CeO2) nanofibers with high porosity are fabricated using an approach involving sol–gel, electrospinning, and calcination. Specifically, cerium(III) acetylacetonate and polyacrylonitrile (PAN) are dissolved in N,N‐dimethylformamide (DMF) and then electrospun into nanofibers. The PAN matrix plays a critical role in stabilizing the porous structure from collapse during calcination in air up to 800 °C. CeO2 porous nanofibers comprising an interconnected network of single crystalline and fully oxidized CeO2 nanoparticles about 40 nm in size are obtained. The hierarchically porous structure of the CeO2 nanofibers enables the facile deposition of Pt nanoparticles via heterogeneous nucleation in a photochemical method. When conducted in the presence of poly(vinyl pyrrolidone) (PVP) and 4‐benzyolbenzoic acid, uniform Pt nanoparticles with an average diameter of 1.7 nm are obtained, which are evenly dispersed across the entire surface of each CeO2 nanofiber. The high porosity of CeO2 nanofibers and the uniform distribution of Pt nanoparticles greatly improve the activity and stability of this catalytic system toward the water‐gas shift reaction. It is believed that this method could be extended to produce a variety of catalysts and systems sought for various industrial applications.

Fabrication and photoelectrochemical study of WO3-based bifunctional electrodes for environmental applications

In this study, unique WO3-based bifunctional electrodes were prepared with the aim of achieving optimal photocatalytic and electrocatalytic activities of WO3 nanoplatelets and Pt nanoparticles, respectively. WO3 nanoplatelets with a high visible light response were directly grown on both sides of a tungsten substrate via a facile hydrothermal method. Pt nanoparticles were deposited on one side of the WO3 electrode, where they served as the electrocatalyst. The prepared electrodes were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), electron dispersive X-ray spectroscopy (EDS) and cyclic voltammetry. Our experimental results revealed that the synthesized WO3 electrodes possessed high photochemical activity under visible light exposure, whereas the deposition of Pt nanoparticles with a large electrochemical active surface area significantly enhanced the electrocatalytic activity of the electrode. Various sets of photodegradation reactions involving Rhodamine B (RhB) were conducted to evaluate the efficacy of the WO3 electrodes, prior to and following the deposition of Pt nanoparticles under both visible light and applied potential. The bifunctional electrode exhibited far greater activity as compared to the WO3 electrode as the sole photocatalyst and WO3–Pt as the sole electrocatalyst, very promising for energy and environmental applications.

Platinum-Enhanced Electron Transfer and Surface Passivation through Ultrathin Film Aluminum Oxide (Al₂O₃) on Si(111)-CH₃ Photoelectrodes.

We report the preparation, stability, and utility of Si(111)-CH3 photoelectrodes protected with thin films of aluminum oxide (Al2O3) prepared by atomic layer deposition (ALD). The photoelectrodes have been characterized by X-ray photoelectron spectroscopy (XPS), photoelectrochemistry (Fc in MeCN, Fc-OH in H2O), electrochemical impedance spectroscopy (EIS), and cyclic voltammetry (CV) simulation. XPS analysis of the growing Al2O3 layer affords both the thickness, and information regarding two-dimensional versus three-dimensional mode of growth. Impedance measurements on Si(111)|CH3|Al2O3 devices reveal that the nascent films (5-30 Å) exhibit significant capacitance, which is attenuated upon surpassing the bulk threshold (∼30 Å). The Al2O3 layer provides enhanced photoelectrochemical (PEC) stability evidenced by an increase in the anodic window of operation in MeCN (up to +0.5 V vs Ag) and enhanced stability in aqueous electrolyte (up to +0.2 V vs Ag). XPS analysis before and after PEC confirms the Al2O3 layer is persistent and prevents surface corrosion (SiOx). Sweep-rate dependent CVs in MeCN at varying thicknesses exhibit a trend of increasingly broad features, characteristic of slow electron transport kinetics. Simulations were modeled as slow electron transfer through a partially resistive and electroactive Al2O3 layer. Lastly, we find that the Al2O3 ultrathin film serves as a support for the ALD deposition of Pt nanoparticles (d ≈ 8 nm) that enhance electron transfer through the Al2O3 layer. Surface recombination velocity (SRV) measurements on the assembled Si(111)|CH3|Al2O3-15 device affords an S value of 4170 cm s(-1) (τ = 4.2 μs) comparable to the bare Si(111)-CH3 surface (3950 cm s(-1); τ = 4.4 μs). Overall, the results indicate that high electronic quality and low surface defect densities can be retained throughout a multistep assembly of an integrated and passivated semiconductor|thin-film|metal device.

Simultaneous Pt deposition and nitrogen doping of graphene as efficient and durable electrocatalysts for methanol oxidation

Nitrogen doping could effectively enhance the catalytical activity of graphene-supported Pt nano-electrocatalysts for methanol oxidation reaction. Previously, the main strategy to the synthesis of Pt/N-graphene is the two-step reaction while it involves the complicated synthesis. In this work, we describe a facile and simple one-pot reaction including the reduction of graphene oxide, nitrogen doping of graphene, and uniform deposition of Pt nanoparticles on doped graphene. Compared with the Pt/graphene catalyst without nitrogen-doping, Pt/N-graphene exhibits excellent activity and durability towards methanol oxidation reaction, which is mainly ascribed to the contribution of the improved dispersion of Pt nanoparticles and the enhanced interaction between it and nitrogen-doped graphene. It is expected that this facile, green and economic single-step synthesis approach for the Pt/N-graphene electrocatalyst could be widely utilized to the nitrogen-doped graphene catalysts.

Highly dispersed platinum sputtered multiwall carbon nanotubes based hydrogen gas sensor at room temperature

We present here, a simple approach for the detection of 0.05% concentration of hydrogen (H2) gas at room temperature conditions using pristine and functionalized multiwall carbon nanotubes (MWCNTs). To enhance the sensitivity of the MWCNTs, platinum (Pt) nanoparticles have been sputtered on the surface of the nanotubes which helps in dissociation H2 molecules to H atoms. The structural and morphological studies of Pt deposited nanotubes were investigated by X-ray diffraction (XRD) spectra and scanning electron microscopy (SEM). The concentration of the deposited Pt nanoparticles on the nanotubes was determined by energy dispersion spectroscopy (EDS). Also, in the present study, Sievert's law is found to be applicable for the H2 gas concentrations (0.05–1%) at room temperature condition. In addition, the influence of bombardment of energetic particles on the surface of nanotubes and its role in the uniform deposition of Pt nanoparticles on the surface of tubes were also discussed.

Photoelectrochemical Hydrogen Evolution: Single-Layer, Conjugated Polymer Films Bearing Surface-Deposited Pt Nanoparticles

In this report, we examine the origin of photocurrent produced by irradiating single layer poly(3-hexylthiophene) (P3HT) films deposited on ITO-coated glass, in aqueous solutions. The photocurrent is found to be largely due to reduction of trace molecular oxygen, which decreases significantly in the presence of an oxygen scavenger. Residual current, < 1 μA cm−2, is observed in acidic media that may be attributed to proton reduction. The addition of a catalyst to aid proton reduction is achieved through photoelectrochemical deposition of Pt nanoparticles from K2PtCl6. Photocurrents at single layer films in aqueous solution increase significantly and bubble formation is observed on the P3HT film that is confirmed to be hydrogen gas. While the photocurrents produced are smaller than those devices employing sophisticated multilayer architectures, the results hold promise that, with further studies, H2 can be evolved at technologically-simple single layer systems with substantially higher rates.

Boron-doped silicon carbide supported Pt catalyst for methanol electrooxidation

Boron-doped silicon carbide (B0.1SiC) synthesized by the carbothermal reduction method was used as support to prepare Pt/B0.1SiC catalyst by cyclic voltammtric deposition of Pt nanoparticles. The crystal structure, surface property and morphology of the catalysts were studied with X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy and transmission electron microscopy techniques and N2 adsorption-desorption experiment. It is shown that B atoms have been incorporated into the SiC lattice sites by substituting Si, which increases the electrical conductivity of SiC. Pt nanoparticles uniformly dispersed on the B0.1SiC support with an average size of 2.7 nm. The prepared Pt/B0.1SiC had a larger electrochemically active area and exhibited higher electrocatalytic activity and stability for methanol oxidation than the Pt/SiC synthesized by the same method. This shows that B-doped SiC is a promising support for preparing high-performance methanol oxidation electrocatalysts.

Controlled Fabrication of Pt Nanocauliflowers on PEDOT Support and Their Superior Electrocatalytic Activity of Methanol Oxidation Reaction

Fabrication of nanoparticles catalyst materials is an active area of research for high impact in chemical(electro-) catalytic reactions and sensors. Particular emphasis has recently been located on the development of advanced catalysts and electrode materials for fuel cells. Fuel cell plays an exact alternative for the current scarcity in the petroleum needs in industrial and other applications. But the main problem is the commercialization of fuel cell catalysts because the usage of precious Pt metal catalyst and very low abundance in the earth crust. The galvanic replacement (GDR) approach in which sacrificial metals are replaced with more noble metals has received important attention. Significantly, it minimizes the amount of precious metal required to create an effective electrocatalysts. Recent research efforts [1-5] have been focused on the preparation of Pt nanoparticles with various metallic or bimetallic core-shell nanostructures on support like carbon, dendrimer, metal oxides etc., by GDR. But no reports on conducting polymer support like poly 3,4-ethylenedioxythiophene, PEDOT.To reduce the usage of Pt catalyst in (monolayer(s) of Pt catalyst) DMFC or PEMFC, galvanic displacement reaction technique was chosen for the decoration of Pt nanocatalyst in PEDOT (Scheme). Non-precious metal nanoparticles such as Cu and Co were electrochemically deposited on PEDOT and were galvanically replaced by Pt nanoparticles as monolayer coverage.Formation of Pt nanocauliflowers on nanofibrillar morphology of PEDOT support was found to be an alternative to carbon support.Various loading (14.91µg/cm2, 26.85 µg/cm2, 32.51µg/cm2, 34.93µg/cm2, and 42.10µg/cm2) of Pt monolayer(s) were achieved on PEDOT and tested for electrocatalytic activity of methanol oxidation reaction (MOR) (Fig.1C). MOR was found to be enhanced by six orders of magnitude compared to direct deposition of Pt nanoparticles. SEM results clearly indicate the formation of Pt nanocauliflowers on nanofibrillar morphology of PEDOT (Fig.1B). Other characterizations like FT-IR, XRD and AFM were carried out to confirm the interactions of Pt nanocatalysts with polymer matrices, Pt facets, surface morphology and synergistic effect of catalyst support. Further, TEM results confirm the size of Pt nanoparticles in the range of 8-30 nm. Fabrication of Pt nanocatalysts on PEDOT by GDR of Cu has superior electrocatalytic performance of MOR. This Pt nanocauliflower-PEDOT catalyst will provide additional option to design and fabrication of catalysts for DMFC/PMFC. References M.Shao, K.Sasaki, N.S. Marinkovic, L.Zhang, and R.R.Adzic, Electrochem. Commun., 2007, 9 2848–2853.Y.Xing, Y.Cai, M. B. Vukmirovic, W-P. Zhou, H. Karan, J.X. Wang, and R.R.Adzic, J. Phys. Chem. Lett., 2010, 1, 3238–3242. 3.D. F. Yancey, E.V. Carino and R.M. Crooks, J. Am. Chem. Soc. 2010, 132, 10988–109894.A. Sarkar and A. Manthiram, J. Phys. Chem. C 2010, 114, 4725–4732.5.D.Chen, Y.Zhao, Y.Fan, X.Peng, X.Wang, and J.Tian., J.Mater. Chem. A, 2013,1, 13227-13232

A new strategy for the synthesis of 3-D Pt nanoparticles on reduced graphene oxide through surface functionalization, Application for methanol oxidation and oxygen reduction

Here, a new functionalization method is introduced to control deposition of Pt nanoparticles on reduced graphene oxide (rGO). In this paper, we investigate the heterogeneous deposition of nanometer-sized Pt islands on rGO subjected to oxidation prior to deposition in the same conditions. We demonstrate that functional groups act as nucleation sites for Pt nanoparticle, and that homogeneous nucleation of small particles can be achieved by combining surface functionalization with diazonium chemistry and appropriate stabilizers in solution. For the purposes of this study, an effective electrochemical mediator is prepared using 4-aminothiophenol-modified rGO as a support decorated with Pt nanoparticles (Pt@SC6H4–rGO) for the oxidation of methanol and reduction of oxygen. The surface morphology and composition of Pt@SC6H4–rGO and Pt@rGO as well as their activity toward methanol oxidation and oxygen reduction are investigated by atomic force microscopy, field emission scanning electron microscopy, X–ray diffraction, cyclic voltammetry, and electrochemical impedance spectroscopy. The results show that decoration of Pt nanoparticle on functionalized rGO leads to three-dimensional Pt nanostructures. Comparisons of the synthesized Pt@rGO and Pt@SC6H4–rGO in terms of their electrochemical performance also show that, compared to Pt@rGO, Pt@SC6H4–rGO has a better electrocatalytic activity for methanol oxidation and oxygen reduction in a solution containing 0.5molL−1 H2SO4 and/or 1.0molL−1 methanol.

Preparation, characterization, and photocatalytic properties of Pt/BiOCl nanoplates

A series of novel Pt/BiOCl nanoplate photocatalysts were synthesized by a photodeposition method. The as-synthesized products were characterized by N2physical adsorption, X-ray diffraction, scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, photoluminescence (PL) emission spectroscopy, and UV-Vis diffuse reflectance spectroscopy (DRS).The photocatalytic activity of the samples was evaluated by photocatalytic degradation of acid orange II under both UV light (λ = 254 nm) and visible light irradiation. The N2physical adsorption test showed that the deposition of Pt nanoparticles could not produce obvious change in the specific surface area of the catalyst. The UV-Vis DRS results indicated that the presence of Pt nanoparticles couldeffectively increase the visible light absorption ability of Pt/BiOCl. The PL spectra indicated that Pt could effectively suppress the recombination of photogenerated hole-electron pairs of Pt/BiOCl. Activity tests showed that the deposition of Pt (1%–2%, mass fraction) greatly promotes the UV right photocatalytic activity. Pt also brought aboutan obvious visible light activity, which could be attributed to the visible light absorption and plasmon photocatalysis role of deposited Pt nanoparticles.

Nano energy technologies

The International Journal of Energy Research (IJER) recognized early on the potential and opportunities of nanomaterials and nanotechnology for energy applications. In the past, several special issues on this theme have been published and separate papers in this category have been regularly published [1,2]. Through improved physical and chemical properties such as increased catalytic activity, large specific surface area, or new functionalities, nanomaterials have shown their applicability for a range of energy technologies such as solar cells, batteries, hydrogen technologies, among others. Nanotechnology is becoming a standard tool to improve the performance or to reduce the cost of novel energy systems. New nano energy devices such as energy harvesting are also emerging. While IJER has launched specific calls for papers in nanotechnology for energy in the past, this time we have chosen extended papers from the 7th International Conference on Surfaces, Coatings & Nanostructured Materials (NANOSMAT 7) which was held in Prague, The Czech Republic, in autumn 2012. A few other paper submissions of interest are also included here. The NANOSMAT conferences have traditionally included several sessions on nanomaterials for energy showing an increasing interest among the science community in this research topic. NANOSMAT conferences have been running since 2005 and due to their great success NANOSMAT-USA and NANOSMAT-Asia have been launched. The papers in this IJER Special Issue on nanotechnology for energy applications deal with solar cells, light-emitting diodes, Li-ion batteries, hydrogen storage, fuel cells, hydrogen production, and energy harvesting. A range of different nanomaterials are also covered such as carbon nanospheres, carbon nanotubes, nanoparticles, nanocomposites, etc. Altogether 14 papers are included in the special issue. A short summary of each paper is presented in the next to introduce the readers of the journal into this special issue. Tsai et al. [3] investigated CuInS2 thin film solar cells in their paper. They looked on the effects of sulfurization and the Cu/in-ratio on the film quality and morphology, which depend very much on the processing conditions. A solar cell with an efficiency of 6.29% was produced. Pimanpang et al. [4] fabricated dye-sensitized solar cells on plastics and stainless steel. The stainless steel was coated with a film of TiO2 nanoparticles and the plastic was made conductive through deposition of Pt-nanoparticles. This fully flexible DSSC solar cell showed an efficiency of 2.72%. Su et al. [5] used ZrO2 nanoparticles to improve the light transmission for a natural pigment-sensitized solar cell in a water-based electrolyte. The nanoparticles improved the light transmission by a factor of eight. An environmentally friendly solar cell with an efficiency of 0.688 % was produced. Ray et al. [6] studied the effect of nitrogen functionalization on the structure of carbon spheres which can potentially be used for energy applications such as solar cells and capacitors. Kasdorf et al. [7] investigated resonant cavity-enhanced light-emitting diodes. Their sandwiched LED design consisted of an electroluminescent liquid crystal between a Bragg mirror deposited on a silicon substrate and a semitransparent top electrode, which enhanced the maximum electroluminescence intensity by a factor of 3–4. Abdel-Hameed et al. [8] investigated a crednerite glassceramic material (CuMnO2) for the first time as for hydrogen storage. The average gravimetric capacity was ~50 gH2/ kg (T = 573K, P = up to 20 bar). The hydrogen adsorbed increased with increasing temperature, but a drawback is the irreversibility of the material requiring improvement of the desorption properties. Attia et al. [9] used a new nanoporous polypyrrole material for hydrogen storage. The material has permanent mesopores on the surface, internal pores, and pockets with sponge-like structures. The maximum reversible hydrogen adsorption capacity was 2.2wt.% at 77K. INTERNATIONAL JOURNAL OF ENERGY RESEARCH Int. J. Energy Res. 2014; 38:415–417 Published online in Wiley Online Library (wileyonlinelibrary.com). DOI: 10.1002/er.3180

Transport properties of metal–semiconductor junctions on n-type InP prepared by electrophoretic deposition of Pt nanoparticles

Electrical properties of highly rectifying Pt/InP junctions fabricated by electrophoretic deposition of Pt nanoparticles are investigated at different temperatures by the measurement of current–voltage and capacitance–voltage characteristics. The forward I–V characteristics of the junction are described by thermionic emissions theory at low forward bias (3kT/q < V < 0.2 V) and by tunnelling current transport through the narrowed space charge region at forward bias V > 0.2 V. The reverse I–V characteristics are analysed in the scope of the thermionic emission model in the presence of shunt resistance. Electrical characteristics of these diodes are sensitive to gas mixtures with a low hydrogen concentration and show an extremely fast response and recovery time.

Supercritical Deposition Route of Preparing Pt/Graphene Composites and Their Catalytic Performance toward Methanol Electrooxidation

The production of effective loading and direct deposition of Pt nanoparticles on graphene is difficult because this intriguing carbon material has highly hydrophobic surface properties. In this work, Pt/graphene sheet (GS) composites were successfully synthesized via a simple, effective, and environmentally benign one-pot supercritical carbon dioxide deposition route using dimethyl (1,5-cyclooctadiene) platinum(II) (PtMe2COD) as a soluble organometallic precursor. The preparation process obviates the need for solvents, which are often volatile and toxic. No post-treatment processes such as washing and drying are needed. Transmission electron microscopy shows that ultrafine metal nanoparticles with an average size as small as ∼2 nm are densely and evenly decorated on the hydrophobic surfaces of GS at Pt loadings up to 80 wt %. Electrochemical studies reveal that the prepared Pt/GS composites possess notably higher catalytic activity and better stability toward methanol electrooxidation in comparison with Pt/multiwalled carbon nanotube and Pt/carbon black composites. The supercritical carbon dioxide deposition method could be easily extended to the fabrication of other graphene-based metal composites with desirable properties by selecting suitable organometallic precursors.

Graphene nanoribbons hybridized carbon nanofibers: remarkably enhanced graphitization and conductivity, and excellent performance as support material for fuel cell catalysts

High electronic conductivity of the support material and uniform distribution of the catalyst nanoparticles (NPs) are extremely desirable for electrocatalysts. In this paper, we present our recent progress on electrocatalysts for fuel cells with simultaneously improved conductivity of the supporting carbon nanofibers (CNFs) and distribution of platinum (Pt) NPs through facile incorporation of graphene nanoribbons (GNRs). Briefly, GNRs were obtained by the cutting and unzipping of multiwalled carbon nanotubes (MWCNTs) and subsequent thermal reduction and were first used as novel nanofillers in CNFs towards high performance support material for electrocatalysis. Through electrospinning and carbonization processes, GNR embedded carbon nanofibers (G-CNFs) with greatly enhanced graphitization and electronic conductivity were synthesized. Chemical deposition of Pt NPs onto G-CNFs generated a new Pt-G-CNF hybrid catalyst, with homogeneously distributed Pt NPs of ∼3 nm. Compared to Pt-CNF (Pt on pristine CNFs) and Pt-M-CNF (Pt on MWCNT embedded CNFs), Pt-G-CNF hybrids exhibit significantly improved electrochemically active surface area (ECSA), better CO tolerance for electro-oxidation of methanol and higher electrochemical stability, testifying G-CNFs are promising support materials for high performance electrocatalysts for fuel cells.

Pt@Nb-TiO2 Catalyst Membranes Fabricated by Electrospinning and Atomic Layer Deposition

A facile method was developed to fabricate fibrous membranes of niobium-doped titania-supported platinum catalysts (Pt@Nb-TiO2) by a two-step approach. The process started with generating niobium-doped titania (Nb-TiO2) fibrous membranes by electrospinning, followed by the deposition of Pt nanoparticles (NPs) using an atomic layer deposition (ALD) technique. The area-specific oxygen reduction reaction (ORR) activity of Pt@TiO2 catalyst membrane was increased by ∼20 folds if 10 at.% of Nb was incorporated into the ceramic fibers. The area-specific activity also increased with the number of ALD cycles, because of the increase of the Pt loading in the catalysts. After post-treatment of the catalyst membrane at high temperature in H2-containing atmosphere, the ORR activity became 0.28 mA/cm2Pt at 0.9 V (vs RHE), because of the improvement in conductivity of Nb-TiO2 fibers and better crystalinity of Pt NPs. The results of accelerated-stability test showed that the Pt@Nb-TiO2 catalyst membrane was highly stable...

The influence of boron dopant on the electrochemical properties of graphene as an electrode material and a support for Pt catalysts

Boron-doped graphene (BGR) is prepared by thermal annealing of graphene oxide (GO) in the presence of boric acid. More defective sites are introduced into GR accompanied by the doping of boron. Low electron transfer resistance towards redox probe is observed at BGR. The BGR modified electrode can effectively distinguish the anodic peaks for ascorbic acid (AA), dopamine (DA), and uric acid (UA). The defective sites of BGR can also act as anchoring sites for the deposition of Pt nanoparticles. When used as a support for Pt electrocatalysts, Pt nanoparticles with an average diameter of 3.2nm are deposited on BGR. The doping of boron into GR facilitates the dispersion of Pt nanoparticles and increases the utilization efficiency of Pt nanoparticles. The Pt/BGR exhibits significant catalytic activity towards the oxidation of methanol. The results demonstrate that BGR is a good support for Pt catalysts or an electrode material compared with the undoped GR.

Electroless Deposition of Platinum Nanoparticles in Room-Temperature Ionic Liquids

The electroless deposition of Pt nanoparticles (Pt-NPs) could be carried out by dissolving potassium tetrachloroplatinate(II) (K2[PtCl4]) in 1-ethyl-3-methylimidazolium (EMI(+)) room-temperature ionic liquids (RTILs) containing bis(trifluoromethylsulfonyl) imide (NTf2(-)) or tetrafluoroborate (BF4(-)) anion and small cations, such as H(+), K(+), and Li(+). In this case, no deposition of Pt-NPs occurred in RTILs without such small cations. The formation of Pt-NPs was only observed in RTILs containing trifluoromethanesulfonimide (HNTf2) and protons at high temperature (≥80 °C) when potassium hexachloroplatinate(IV) (K2[PtCl6]) was dissolved in the RTILs. The obtained Pt-NPs gave a characteristic absorption spectrum of ultrasmall Pt-NPs. The ultrasmall and uniform Pt-NPs of ca. 1-4 nm in diameter were produced and the Pt-NPs/EMI(+)NTf2(-) dispersion was kept stably for several months without adding any additional stabilizers or capping molecules. The identified Fourier-transform patterns along the [0 1 1] zone axis were observed for the TEM images of Pt-NPs. On the basis of the results obtained, a probable mechanism of the electroless formation of Pt-NPs is discussed.