H2PtCl6 Research Articles

The Effect of Mg and Zn Dopants on Pt/Al2O3 for the Dehydrogenation of Perhydrodibenzyltoluene

The effects of Mg and Zn dopants on the catalytic performance of Pt/Al2O3 catalyst were investigated for dehydrogenation of perhydrodibenzyltoluene (H18-DBT) as a liquid organic hydrogen carrier. Al2O3 supports were modified with Mg and Zn to produce Mg-Al2O3 and Zn-Al2O3 with a target loading of 3.8 wt.% for dopants. The modified supports were impregnated with chloroplatinic acid solution to produce the catalysts Pt/Al2O3, Pt/Mg-Al2O3 and Pt/Zn-Al2O3 of 0.5 wt.% Pt loading. Thereafter, the catalysts were characterised using inductively coupled plasma- optical emission spectrometry, scanning electron microscopy-energy dispersive X-ray spectroscopy, hydrogen temperature-programmed reduction, carbon-monoxide pulse chemisorption, ammonia temperature-programmed desorption, X-ray diffraction and transmission electron microscopy. The dehydrogenation experiments were performed using a horizontal plug flow reactor system and the catalyst time-on-stream was 22 h. Pt/Mg-Al2O3 showed the highest average hydrogen flowrate of 29 nL/h, while an average of 27 nL/h was obtained for both Pt/Al2O3 and Pt/Zn-Al2O3. This has resulted in a hydrogen yield of 80% for Pt/Mg-Al2O3, 71% for Pt/Zn-Al2O3 and 73% for Pt/Al2O3. In addition, the conversion of H18-DBT ranges from 99% to 92%, Pt 97–90% and 96–90% for Pt/Mg-Al2O3, Pt/Zn-Al2O3 and Pt/Al2O3, respectively. Following the latter catalyst order, the selectivity to dibenzyltoluene (H0-DBT) ranges from 78% to 57%, 75–51% and 71–45%. Therefore, Pt/Mg-Al2O3 showed improved catalytic performance towards dehydrogenation of H18-DBT.

Fabrication of platinum nanowires by centrifugal electrospinning method for proton exchange membrane fuel cell

The centrifugal electrospinning method is employed to fabricate platinum (Pt) nanowires and its application for proton exchange membrane fuel cell (PEMFC) is evaluated. The nanowires are produced from a polymer solution containing hexachloroplatinic acid hydrate as Pt precursor and polyvinyl pyrrolidone (PVP). The effects of system parameters on the morphology of Pt nanowires are studied including the PVP concentration, rotation speed of spinneret, and applied electric field. The electrochemically active surface area (ESA) of the Pt nanowires is characterized by cyclic voltammetry tests. The produced Pt nanowires are also used as electrocatalysts in the cathode of PEMFC and the cell performance is tested. Results show the centrifugal electrospinning method can successfully produce Pt nanowires with mean diameter of 54 ± 14 nm and ESA of 5.64m2g-1, which are comparable to those of traditional electrospun Pt nanowires. The production rate of Pt nanowires can be improved greatly in comparison with the conventional electrospinning technique. It is also found that by the accelerated degradation tests, Pt nanowires demonstrate better durability than commercial Pt/C and the employment of Pt nanowires as electrocatalysts mixed with Pt/C can enhance the fuel cell performance. The present results reveal the centrifugal electrospinning method is an efficient approach to fabricate Pt nanowires for the application in PEMFCs. Novelty statement A centrifugal electrospinning device was designed to fabricate Pt nanowires successfully with good morphology. The production rate of Pt nanowires is enhanced greatly in comparison with the conventional electrospinning method. Electrocatalysts composed of the produced Pt nanowires and Pt/C is found to be able to improve the performance of PEMFC.

Control and Impact of Metal Loading Heterogeneities at the Nanoscale on the Performance of Pt/Zeolite Y Catalysts for Alkane Hydroconversion.

The preparation of zeolite-based bifunctional catalysts with low noble metal loadings while maintaining optimal performance has been studied. We have deposited 0.03 to 1.0 wt % Pt on zeolite H-USY (Si/Al ∼ 30 at./at.) using either platinum(II) tetraammine nitrate (PTA, Pt(NH3)4(NO3)2) or hexachloroplatinic(IV) acid (CPA, H2PtCl6·6H2O) and studied the nanoscale Pt loading heterogeneities and global hydroconversion performance of the resulting Pt/Y catalysts. Pt/Y samples prepared with PTA and a global Pt loading as low as 0.3 wt % Pt (nPt/nA = 0.08 mol/mol, where nPt is the number of Pt surface sites and nA is the number of acid sites) maintained catalytic performance during n-heptane (T = 210–350 °C, P = 10 bar) as well as n-hexadecane (T = 170–280 °C, P = 5 bar) hydroisomerization similar to a 1.0 wt % Pt sample. For Pt/Y catalysts prepared with CPA, a loading of 0.3 wt % Pt (nPt/nA = 0.08 mol/mol) sufficed for n-heptane hydroisomerization, whereas a detrimental effect on n-hexadecane hydroisomerization was observed, in particular undesired secondary cracking occurred to a significant extent. The differences between PTA and CPA are explained by differences in Pt loading per zeolite Y crystal (size ∼ 500 nm), shown from extensive transmission electron microscopy energy-dispersive X-ray spectroscopy experiments, whereby crystal-based nPt/nA ratios could be determined. From earlier studies, it is known that the Al content per crystal of USY varied tremendously and that PTA preferentially is deposited on crystals with higher Al content due to ion-exchange with zeolite protons. Here, we show that this preferential deposition of PTA on Al-rich crystals led to a more constant value of nPt/nA ratio from one zeolite crystal to another, which was beneficial for catalytic performance. Use of CPA led to a large variation of Pt loading independent of Al content, giving rise to larger variations of nPt/nA ratio from crystal to crystal that negatively affected the catalytic performance. This study thus shows the impact of local metal loading variations at the zeolite crystal scale (nanoscale) caused by different interactions of metal precursors with the zeolite, which are essential to design and synthesize optimal catalysts, in particular at low noble metal loadings.

Initial nucleation process in the synthesis of Platinum Nanoparticle from chloroplatinic acid

The size, morphology, and polymorphism of nano-materials, the key factors determining their physicochemical properties, are significantly affected by the nucleation processes from precursors. Understanding the nucleation kinetics at the atomic scale is fundamental to the designed synthesis of nano-materials with tailored composition, shape and size. Here we report our investigation on the nucleation process in synthesis Platinum nano-particles by chemical reduction of chloroplatinic acid in methanol and methanol/water mixed system. In synergy with the liquid chromatography mass spectrometry (LCMS) and first-principle transition-state calculations, specific reaction processes at the pre-nucleation stage are revealed in which the precursor chloroplatinic acid (H2PtCl6) undergoes a two-step reduction process to form divalent and non-valent Pt-contained clusters, respectively. It is found that in both steps, the presence of water molecular can lower the activation energy and accelerate the reaction rate through a proton transport mechanism. Moreover, through free energy analysis and ab-initio molecular dynamic simulation, we identified the initial nucleation process which is characterized by the formation of Pt-Pt bond between two divalent Pt (II)-contained clusters. The theoretical calculations explain the pre-nucleation reaction paths and the nucleation process, consistent with the LCMS measurements and previous XAFS results. This work indicates the nucleation processes in chloroplatinic acid/methanol/water system exhibit more complexities than that described by the classical nucleation theory as well as previous research results on the same system. The finding may shed light upon the size-and-shape-controlled synthesis of noble metal nanoparticles.

Cu@Pt/NCNT preparation and electrochemical performance

In this paper, platinum–copper (Pt–Cu) alloy colloid was prepared using the microwave-assisted polyol reduction method with chloroplatinic acid and copper chloride as precursors. During the preparation, the metal particles were loaded on the nitrogen-doped carbon nanotubes (NCNTs) using the sol–gel method. Catalysts with different metal proportions were prepared to investigate the activity of oxygen reduction reaction (ORR), and commercial Pt/C catalyst was used as control. A series of characterizations including X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and X-ray photoelectron spectroscopy were employed to study the morphology and composition of the catalysts. The results revealed that the Pt–Cu alloy can be well loaded on NCNTs and displayed good ORR catalytic activities, especially CuPt–NCNT1:3 with the mass activities as 0.12A/mgPt; Ik was 0.56 mA/cm2Pt, which was better than those of the commercial Pt/C catalyst. It was also found that the half-wave potential and diffusion-limited current curves were close to those of the commercial ones, which demonstrate a simple and effective way to prepare the catalyst for fuel cell.

Effect of Synthesis Conditions of Platinum/Reduced Graphene Oxide Nanocomposites on the Electrochemical Behaviors of Cathodes in Dye-Sensitized Solar Cells

This study deals with the preparation and characterization of platinum/reduced graphene oxide (Pt/rGO) as an efficient cathode for dye-sensitized solar cells. Herein, the Pt/rGO material was synthesized by co-precipitation from hexachloroplatinic acid (H2PtCl6) and graphene oxide (GO) precursors. The fabrication of cathodes from Pt/rGO composite paste was carried out using screen-printing paste. The electrochemical behaviors of as-prepared cathodes were analyzed by cyclic voltammetry; the performance of fabricated DSSCs was measured by current density–voltage (J-V) curves and electrochemical impedance spectroscopy. The structural characteristics of the Pt/rGO binary composites were confirmed by Fourier-transform infrared spectroscopy, Raman spectroscopy, x-ray diffraction (XRD), and transmission electron microscopy. Empirical data showed that choosing ascorbic acid as a reducing agent at a ratio of 5:1 between ascorbic acid weight and precursor mixture weight, as well as a GO weight percentage of 20% fabricated DSSCs successfully with a conversion efficiency of 6.25%, which was approximately 90% compared to that of pure commercial Pt material. Characterization results indicated that the Pt nanoparticles were homogeneously distributed on the rGO sheets with an average diameter of less than 25 nm. The Pt/rGO hybrid composite is highly expected to replace Pt in the fabrication of cathodes in DSSCs for low-cost DSSC production in the promising future.

Facile engineering of silk fibroin capped AuPt bimetallic nanozyme responsive to tumor microenvironmental factors for enhanced nanocatalytic therapy.

Background: Reactive oxygen species (ROS), as a category of highly reactive molecules, are attractive for eliminating tumor cells in situ. However, the intrinsic tumor microenvironment (TME) always compromises treatment efficacy. In another aspect, silk fibroin (SF), as a category of natural biomacromolecules, is highly promising for synthesis of metallic nanocrystals via biomineralization.Methods: As a proof-of-concept study, AuPt bimetallic nanozyme derived from bioinspired crystallization of chloroauric acid and chloroplatinic acid was facilely developed in the presence of silk fibroin (SF). Antitumor effects caused by the as-synthesized AuPt@SF (APS) nanozyme were demonstrated in 4T1 tumor cells in vitro and xenograft tumor models in vivo.Results: APS nanozyme can decompose glucose to constantly supply H2O2 and deplete intracellular glutathione (GSH). APS nanozyme can simultaneously convert adsorbed O2 and endogenic H2O2 into superoxide radicals (•O2-) and hydroxyl radical (•OH), respectively, upon highly efficient catalytic reaction. Subsequently, these cytotoxic ROS cause irreversible damage to the cell membrane, nucleic acid and mitochondria of tumors. Upon fluorescence/photoacoustic (FL/PA)-imaging guidance, remarkable tumor damage based on the current nanoplatform was confirmed in vivo.Conclusion: The objective of our investigation is to supply more useful insights on the development of SF-based nanocatalysts, which are specifically responsive to TME for extremely efficient tumor theranostics.

Реакция пентафенилфосфора с гексахлороплатиновой кислотой

Tetraphenylphosphonium hexachloroplatinate (1) was synthesized by the interaction of pentaphenylphosphorus with hexachloroplatinic acid in acetone. The recrystallization of complex 1 from dimethylsulfoxide gave tetraphenylphosphonium dimethylsulfoxidopentachloroplatinate (2). The compounds have been characterized by IR-spectroscopy and X-ray analysis. The absorption bands characterizing stretching vibrations of the phenyl groups are present in the IR spectra, recorded on a Shimadzu IRAffinity-1S Fourier spectrometer in the 4000–400 cm–1 area in KBr pellets. According to the X-ray analysis, the compound unit cell parameters are: triclinic syngony, space group (1, 2), а = 10.205(10), b = 10.970(15), c = 12.160(11) Å (1), а = 7.7667(4), b = 13.3069(7), c = 14.2562(7) Å (2), a = 73,65(4)°, β = 80.64(3)°, g = 77.48° (1), a = 80.972(4)°, β = 88.205(4)°, g = 89.199(4)° (2), V = 1272(2) Å3 (1), 1454.38(13) Å3 (2). The crystals of complexes 1 and 2 consist of the tetrahedral tetraphenylphosphonium cations and octahedral anions. In cations the phosphorus atoms have a slightly distorted tetrahedral environment (the CPC angles are 107.8(3)-113.2(3)° (1), 105.9(3)–112.9(3)° (2), the P-C distance is 1.785(6)-1.805(6) Å (1), 1.783(7)–1.791(6) Å (2). Platinum atoms in the anions of complexes 1 and 2 are hexacoordinated. In complex 2 the dimethyl sulfoxide ligand is coordinated with the Pt atom via the sulfur atom 2.290(2) Å. Complete tables of coordinates of atoms, bond lengths and valence angles are deposited at the Cambridge Structural Data (CCDC 1865783, 829586 http://www.ccdc.cam.ac.uk).

Synergistic Effect of Platinum Single Atoms and Nanoclusters Boosting Electrocatalytic Hydrogen Evolution

Maximizing atomic utilization of precious metal-based catalysts is of great significance in heterogeneous catalysis, also becoming a useful strategy to develop efficient electrocatalysts for hydrog...

Optical transparency and conductivity of oriented platinum nanonetworks on a glass surface

The work is aimed at creating an optically transparent conductive coating based on platinum nanowires which can become an alternative to the existing indium tin oxide. This coating can be used as transparent electrodes in solar panels, organic LEDs and many areas of modern electronics and optoelectronics. In work, the dependence of the sheet resistance of oriented platinum nanowires network on the amount of metal used is investigated. Oriented platinum nanowires are obtained by chemical deposition from an aqueous solution of hexachloroplatinic acid on a glass surface. The topography of the deposited metal layer on the glass is visualized by atomic force microscopy. It has been established that the platinum layer has good optical transparency. The synthesized coating would be of interest in terms of applicability as an optically transparent electrode.

Investigations on a platinum catalyzed membrane for electrolysis step of copper‐chlorine thermochemical cycle for hydrogen production

SummaryConsidering the low temperature demand (~550°C maximum) and high efficiency (~43%), Cu–Cl thermochemical water splitting cycle has immense potential as a futuristic scalable hydrogen generation process. CuCl/HCl electrolysis is the crucial hydrogen generation step in the Cu–Cl thermochemical cycle. The efficiency of this electrolysis process is highly dependent on the performance of the membrane electrode assembly (MEA) employed. To explore the suitability of the platinized membrane for this step, in this study, we have investigated a Pt/Nafion‐117 MEA prepared by in‐situ impregnation‐reduction method for CuCl/HCl electrolysis. A single‐cell PEM‐type electrolyser (4 cm2 active area) consisting of serpentine channels (2 cm × 2 cm) grooved in graphite flow field plates was designed and fabricated to carry out the CuCl/HCl electrolysis. Platinum electrocatalyst was deposited on Nafion‐117 membrane on the cathodic side by reduction of hexachloroplatinic acid (H2PtCl6) with sodium borohydride (NaBH4) by the impregnation‐reduction method which served as the MEA. Monodispersed nanocrystalline Pt particles formed a ~30 μm thick electrocatalyst layer on the membrane. Pt/Nafion‐117 MEA was found to be effective for CuCl /HCl electrolysis. In a PEM‐type electrolyser with Ar‐purged 0.2 M CuCl in ~2 M HCl solution as anolyte flowing at ~ 8.8 mLmin−1, a current density of ~100 mA cm−2 was achieved at a cell voltage of 1 V. However, undesired Cu‐crossover could be noticed from anode to cathode side during operation.

Selective Loading of Platinum or Silver Cocatalyst on a Hydrogen-Evolution Photocatalyst in an Overall Water-Splitting System, Silver-Inserted Zinc Rhodium Oxide and Bismuth Vanadium Oxide

Since Fujishima and Honda reported photoelectrochemical water splitting using a TiO2 electrode in 1972 [1], solar hydrogen (H2) production from water using a photocatalyst has attracted attention as a clean energy resource. Most recent researches have been focusing on the visible-light sensitization of catalysts to effectively utilize solar energy. Recently, we have developed a novel solid-state photocatalyst by inserting silver (Ag) or gold (Au) as an electron mediator between zinc rhodium oxide (ZnRh2O4, Eg of 1.2 eV) and bismuth vanadate (Bi4V2O11, Eg of 1.7 eV) as H2- and oxygen (O2)-photocatalysts, respectively (ZnRh2O4/Ag/Bi4V2O11, ZnRh2O4/Au/Bi4V2O11) [2-4]. In this system, we achieved overall pure-water splitting, liberating H2 and O2 simultaneously from pure water at a stoichiometric ratio 2 to 1, photocatalyzed via the inserted Ag or Au which could transfer photo-excited electrons from the conduction band (CB) of Bi4V2O11 to the valence band (VB) of ZnRh2O4. The ZnRh2O4/Ag (Au)/Bi4V2O11 utilized visible light up to 740 nm. Notably, the ZnRh2O4/Ag/Bi4V2O11 system did not include a cocatalyst, which is inevitably required for the water-splitting reaction due to increasing the lifetime of electron-and-hole pairs and storing either electrons or holes. Thus, in the present study, we tried to load a cocatalyst, Ag or Pt, selectively onto the H2-evolution photocatalyst, ZnRh2O4, in ZnRh2O4/Ag/Bi4V2O11 to enhance the photosensitivity of this system.Powdered ZnRh2O4/Ag/Bi4V2O11 was prepared following the previously reported procedures [2]. The photo-deposition of Pt or Ag was performed under light irradiation at wavelength longer than 850 nm using hexachloroplatinic acid (H2PtCl6∙6H2O) or silver nitrate (AgNO3) solution as the source of Pt or Ag. Under these irradiated light conditions, only ZnRh2O4 was photo-excited because the energy of irradiated light was higher than the band-gap energy of ZnRh2O4 (1.2 eV) but smaller than that of Bi4V2O11 (1.7 eV). Due to the specific photoexcitation of ZnRh2O4, Pt or Ag was expected to be only photo-deposited onto this material, generating Pt/ZnRh2O4/Ag/Bi4V2O11 and Ag/ZnRh2O4/Ag/Bi4V2O11.To quantitatively determine the valencies of Pt and Ag, and analyze the amounts of Pt and Ag in the photocatalysts (bare ZnRh2O4/Ag/Bi4V2O11, Pt/ZnRh2O4/Ag/Bi4V2O11, and Ag/ZnRh2O4/Ag/Bi4V2O11), a peak deconvolution method was applied to the Bi 4f, Ag 3d, and Pt 4f spectra. Ag 3d peaks for the three photocatalysts were deconvoluted by one pair of Ag 3d peaks, Ag 3d5/2 and Ag 3d3/2, which were assigned to metallic Ag (Ag0). These results indicate that Ag was included as a metallic particle in the three photocatalysts. In contrast, the Pt 4f peaks for Pt/ZnRh2O4/Ag/Bi4V2O11 were deconvoluted by three pairs of Pt 4f peaks, attributable for metallic Pt (Pt0), Pt2+, and Pt3+ The atomic ratios of Pt0, Pt2+, and Pt3+ vs. total Pt were calculated to be 0.63, 0.25, and 0.12, respectively. Moreover, as we considered that the Bi4V2O11 surface remained unchanged even after the Pt or Ag deposition, we estimated the amount of Pt or Ag in the photocatalysts based on the amount of Bi. The weight percentage (wt%) of Ag in the three photocatalysts was calculated. As expected, the amount of Ag in ZnRh2O4/Ag/Bi4V2O11 and Pt/ZnRh2O4/Ag/Bi4V2O11 was identical at 2.1 wt%. The total amount of Ag in Ag/ZnRh2O4/Ag/Bi4V2O11 was calculated to be 3.2 wt%, thus the Ag cocatalyst deposited in Ag/ZnRh2O4/Ag/Bi4V2O11 was estimated to be 1.1 wt% based on the assumption that the amount of Ag inserted in Ag/ZnRh2O4/Ag/Bi4V2O11 was 2.1 wt%, identical to those in ZnRh2O4/Ag/Bi4V2O11 and Pt/ZnRh2O4/Ag/Bi4V2O11. Similarly, the amount of Pt cocatalyst in Pt/ZnRh2O4/Ag/Bi4V2O11 was calculated to be 1.2 wt%.The bare ZnRh2O4/Ag/Bi4V2O11, Pt/ZnRh2O4/Ag/Bi4V2O11, and Ag/ZnRh2O4/Ag/Bi4V2O11 photocatalysts evolved H2 and O2 from water at a molar ratio of ca. 2 to 1, indicating that the overall water splitting reaction proceeded. The deposition of Pt or Ag 3-fold enhanced the H2 and O2 evolution rates compared to those of bare ZnRh2O4/Ag/Bi4V2O11, demonstrating that Pt and Ag functioned as cocatalysts for the overall water-splitting reaction [5].This work was performed by Assoc. Prof. T. Takashima, Mr. M Yoda, and Mr. J. Osaki. I am deeply grateful to JSPS KAKENHI (Grant-in-Aid for Scientific Research) (B), Grant Number 17H03126 for its financial support.

Plasmonic Platinum-Titania Photocatalyst Nanocomposite for Solar Application and Protective Titania Modified Nanocomposite Resin Coatings Against Steel Corrosion

In the study, two main applications of titania nanocomposites are presented; solar application and corrosion protection. A chemical protocol for preparing a unique platinum-titania photocatalyst via solvothermal chemical reaction. This process utilized chloroplatinic acid hexahydrate and titanium butoxide as precursors in the presence of dimethyl sulfoxide. Synthesis was followed by morphological and crystalline structural characterizations as well as nanoparticle size distribution. Optical investigations revealed optical responses after UV-induced excitation. This photocatalyst also revealed photodegradation of diuron (a model algicide) and improved performance for photodecomposition after an hour. This composite also exhibited a defined self-cleaning ability when incorporated within fabrics.For long-term performance in outdoor applications, compatible inorganic fillers with reliable corrosion inhibiting abilities are incorporated within acrylic coatings for metallic structures susceptible to atmospheric degradation. However, challenges still abound on the selection criteria for appropriate fillers suitable for most coatings, from both inorganic and organic pools. In this work, titania nanoparticles (TiO2NPs) were prepared from titanium ethoxide via sol-gel technique. Titania-modified acrylic resins were subsequently synthesized by incorporating TiO2NPs within different grams of an acrylic base resin. In-depth characterization has been conducted for both prepared TiO2NPs and the synthesized titania modified acrylic coatings. The inorganic/organic hybrid resin coating was applied on mild steel to prevent its corrosion in 5 wt% NaCl solution. The presence of TiO2NPs within these acrylic coatings further blocked inherent pathway to which corrosive ions and molecule could have permeated the coating; hence, delaying steel corrosion. The optimum amount of TiO2NP fillers required to prepare an anticorrosion acrylic resin coating with efficient barrier properties has been identified.These particles further strengthened the gross mechanical properties of the coatings in terms of bulk structural reinforcement while also enhancing their barrier performances. This work highlights the correlation between coating content and the failure mechanisms or loss of corrosion resistance of degrading acrylic coatings in saline medium. These modified acrylic resin coatings may have a future as solar and outdoor protective coatings. Keywords: Platinum-titania photocatalyst; Titania nanoparticles; Acrylic resin coatings; Protective coatings; Corrosion; Solar.

Host-Guest Thin Films by Confining Ultrafine Pt/C QDs into Metal-Organic Frameworks for Highly Efficient Hydrogen Evolution.

Combining the features of host templates and guest species is an efficient strategy to optimize the photo/electrocatalytic performance. Herein, novel host-guest thin-film electrocatalysts are designed and developed with Pt doped carbon (Pt/C) confined into porphyrin-based metal-organic frameworks (MOFs). Porous MOF PCN-222 and PCN-221 thin films are used as the host templates and fabricated using vapor-assisted deposition method, and then the guest Pt/C quantum dots are encapsulated into the MOFs by loading the glucose mixed H2 PtCl6 and heating at 200 °C. Thanks to the confinement effect of MOF pores, the homogenous and ultrafine Pt/C nanowires (Pt/CNWs) and nanodots (Pt/CNDs) are confined in nanochannels of PCN-222 and nanocages of PCN-221 (Pt/CNW@PCN-222 and Pt/CND@PCN-221), respectively. The electrocatalytic study shows that the host-guest thin films have highly-efficient electrocatalytic hydrogen evolution performance under light irradiation. Furthermore, the time-resolved photoluminescent results reveal that Pt/CNW@PCN-222 has a faster charge transfer (441 ps) from PCN-222 to Pt/CNWs comparing to that (557 ps) of Pt/CND@PCN-221, indicating the guests with different shapes play an important role in the electrocatalytic performance. This work serves to present both the outstanding level of control in the precise synthesis and high potential for nanocomposite thin films in photo-electrocatalytic application.

Green and efficient synthesis of pinacol over photoactive acetonyl-platinum complexes on Pt nanoparticle surfaces photocatalyst

Green approaches to prepare high-value-added products from inexpensive raw materials is a popular research topic in chemical engineering. In the present paper, PtNPinsitu photocatalyst was prepared by in-situ photoreduction of chloroplatinic acid in the presence of acetone. Further, the sacrificial agent isopropanol could be selectively oxidized via C–C coupling into pinacol over the PtNPinsitu photocatalyst, and the yield of pinacol could reach 68.89% after raction of 18 h. Radical capture and isotope labeling experiments confirmed that the photocatalytic selective oxidation of isopropanol follows the OH oxidation mechanism. The results not only establish a green method for pinacol synthesis but also enrich the Platinum type of photocatalytic coupling reactions.

Influence of the Preparation Method on the Physicochemical and Catalytic Properties of Platinum Catalysts Supported on Bayerite Alumina for the Partial Oxidation Reactions of Hydrocarbons

Platinum catalysts supported onto bayerite alumina were synthesized and studied. Alumina of the θ-Al2O3 type, which was prepared from metallic aluminum by an aluminate method, was used as a support, and platinum(IV) nitrate and hydrogen hexachloroplatinate(IV) precursors containing Pt4+ ions were used for supporting an active component. The catalysts were studied by physicochemical methods such as X-ray phase analysis, X-ray photoelectron spectroscopy, transmission electron microscopy, and ultraviolet-visible diffuse reflection spectroscopy. It was found that platinum occurred in a finely dispersed state in both of the catalysts, and it was uniformly distributed over the support surface. The particle sizes were 2.8 and 0.9 nm in the samples synthesized from platinum(IV) nitrate and hydrogen hexachloroplatinate(IV), respectively. The most uniform surface distribution, high dispersity, and a narrow particle-size distribution were obtained with the use of hydrogen hexachloroplatinate(IV). The catalysts were tested in the partial oxidation of natural gas. The catalyst synthesized using platinum(IV) nitrate afforded an almost thermodynamically equilibrium distribution of the reaction products of partial oxidation at a temperature of 700–800°С.

Effect of Pt nanoparticle decoration on the H2 storage performance of plasma-derived nanoporous graphene

A nanoporous and large surface area (∼800 m2/g) graphene-based material was produced by plasma treatment of natural flake graphite and was subsequently surface decorated with platinum (Pt) nano-sized particles via thermal reduction of a Pt precursor (chloroplatinic acid). The carbon-metal nanocomposite showed a ∼2 wt% loading of well-dispersed Pt nanoparticles (<2 nm) across its porous graphene surface, while neither a significant surface chemistry alteration nor a pore structure degradation was observed due to the Pt decoration procedure. The presence of Pt seems to slightly promote the hydrogen sorption behavior at room temperature with respect to the pure graphene, thus implying the rise of “weak” chemisorption phenomena, including a potential hydrogen “spillover” effect. The findings of this experimental study provide insights for the development of novel graphene-based nanocomposites for hydrogen storage applications at ambient conditions.

EFFECT OF POLYVINYLPYRROLIDONE ON THE SYNTHESIS AND CATALYTIC PROPERTIES OF PLATINUM-CONTAINING OXYGEN ELECTROREDUCTION CATALYSTS

Results of the work on the synthesis of highly effective nanocomposite platinum-containing oxygen reduction electrocatalysts for hydrogen-oxygen fuel cells are presented and ways of increasing their activity are considered. Fuel cells (FCs) represent the most promising renewable and environmentally friendly energy sources that can operate at low temperatures with high efficiency and with low or zero levels of hazardous waste. The main problem of fuel cells is that the oxygen reduction reaction is slowed down in relation to the hydrogen oxidation reaction, which leads to an increase in the overvoltage at the cathode and, as a result, to a decrease in the productivity of FCs. To solve this problem, the new methods are being developed for the synthesis of highly efficient platinum electrocatalysts, which currently have the best performance, since platinum has the highest specific catalytic activity among other materials used in low temperature FCs. The purpose of this work is to determine the optimal composition of reaction mixture and conditions for the preparation of a platinum based catalyst for oxygen electroreduction where Vulcan XC-72 nanodispersed carbon black is used as a carrier. We have worked out 6 methods for preparing Pt (40 %)/XC-72 catalysts. To evaluate the activity of the prepared catalysts and to determine the kinetic parameters of the oxygen reduction on them, cathodic stationary polarization curves were recorded in a 0.5 M H2SO4 solution on a floating gas diffusion electrode superficially modified by the catalysts. For preparation of all electrocatalysts we are used 3.6 ml of a hexachloroplatinic acid (H2PtCl6) solution, containing 18.8 mg Pt/ml, 100 ml of ethylene glycol or its mixture with deionized water (3 : 1) and 100 mg of Vulcan XC-72 carbon black, previously oxidized in HNO3 solution. 1 M NaOH or KOH solutions were used to create the necessary medium (pH = 11). Some Pt(40 %)/XC-72 electrocatalysts were prepared when additions of polyvinylpyrrolidone (PVP) (100 mg or 300 mg) and/or 60 ml of formaldehyde were introduced into reaction mixture. Temperature during syntheses was in the range 75 - 160 °C. It was shown that reducing the synthesis temperature from 160 to 75 °C and introduction of PVP together with formaldehyde into reaction mixture had a positive effect on the activity of obtained nanocomposite platinum-containing catalysts Pt(40 %)/XC-72 for oxygen electroreduction.The sizes of the obtained platinum clusters on the surface of carbon black nanoparticles were in the range of 1.7 - 5.7 nm, and under optimal synthesis conditions they were evenly and densely distributed on the surface of the carbon carrier. The obtained kinetic characteristics of oxygen electroreduction on the studied catalysts indicate that the mechanism of this process depended on both the current density and the method of catalyst synthesis.

Concentration effect on properties of Pt-NiOx nanocompounds converted from mixed chloroplatinic acid and nickel acetate precursor films using an atmospheric-pressure plasma jet

A direct current-pulse nitrogen atmospheric-pressure plasma jet (APPJ) is used to convert Pt-NiOx nanocompounds from liquid precursor films consisting of a mixture of chloroplatinic acid and nickel acetate. The Pt-NiOx nanoparticles are well-distributed on the fluorine-doped tin oxide (FTO) glass substrates. X-ray photoelectron spectroscopy results indicate that the reaction product mainly contains metallic Pt and oxidized Ni. Electrochemical impedance spectroscopy and Tafel experiments reveal an improvement in electrochemical catalytic effects. The APPJ-processed Pt-NiOx nanocompounds on FTO glass substrates are used as the counter electrodes (CEs) of dye-sensitized solar cells (DSSCs). J − V curves indicate that DSSCs with 5-s APPJ-processed Pt-NiOx CEs showed significantly improved performance. The sample properties become stable after ∼45 s of APPJ calcination. Precursor solutions with three different mole ratios of chloroplatinic acid and nickel acetate are investigated. With the addition of an adequate amount of oxidized nickel, the transfer charge current density and electrochemical catalytic effects are enhanced.

Dodecahedral Au/Pt Nanobowls as Robust Plasmonic Electrocatalysts for Methanol Oxidation under Visible-Light Illumination.

Plasmonic nanostructures with large absorption areas under resonant excitation have been utilized extensively in photon-assisted applications. In this work, dodecahedral Au nanobowls were first prepared by an easy and template-free method only through the introduction of H2 PtCl6 and I- during the growth procedure. The Au nanobowls show electron-field enhancement due to the high curvature of the bowl edge, the open region, and dodecahedral morphology. Au/Pt nanobowls, which couple plasmonic Au and catalytic Pt, were then constructed as plasmonic electrocatalysts for methanol oxidation. The mass activity reached 497.6 mA mg-1 under visible-light illumination, which is 1.9 times that measured in the dark. Simultaneously, the electrocatalytic stability is also greatly improved under light excitation. The enhanced properties of the plasmonic Au/Pt electrocatalysts are ascribed to the synergistic effect of the plasmon-enhanced photothermal and hot-carrier effects on the basis of experimental investigations. This work thus offers an effective methodology to construct efficient plasmonic electrocatalysts for fuel cells.