F:Highly flammable;
7440-06-4Relevant articles and documents
Platinum nanofilm formation by EC-ALE via redox replacement of UPD copper: Studies using in-situ scanning tunneling microscopy
Kim, Youn-Geun,Kim, Jay Y.,Vairavapandian, Deepa,Stickney, John L.
, p. 17998 - 18006 (2006)
The growth of Pt nanofilms on well-defined Au(111) electrode surfaces, using electrochemical atomic layer epitaxy (EC-ALE), is described here. EC-ALE is a deposition method based on surface-limited reactions. This report describes the first use of surface-limited redox replacement reactions (SLR3) in an EC-ALE cycle to form atomically ordered metal nanofilms. The SLR 3 consisted of the underpotential deposition (UPD) of a copper atomic layer, subsequently replaced by Pt at open circuit, in a Pt cation solution. This SLR3 was then used a cycle, repeated to grow thicker Pt films. Deposits were studied using a combination of electrochemistry (EC), in-situ scanning tunneling microscopy (STM) using an electrochemical flow cell, and ultrahigh vacuum (UHV) surface studies combined with electrochemistry (UHV-EC). A single redox replacement of upd Cu from a PtCl42- solution yielded an incomplete monolayer, though no preferential deposition was observed at step edges. Use of an iodine adlayer, as a surfactant, facilitated the growth of uniformed films. In-situ STM images revealed ordered Au(111)-(√3 × √3)R30°-iodine structure, with areas partially distorted by Pt nanoislands. After the second application, an ordered Moire pattern was observed with a spacing consistent with the lattice mismatch between a Pt monolayer and the Au(111) substrate. After application of three or more cycles, a new adlattice, a (3 × 3)-iodine structure, was observed, previously observed for I atoms adsorbed on Pt(111). In addition, five atom adsorbed Pt-I complexes randomly decorated the surface and showed some mobility. These pinwheels, planar PtI4, complexes, and the ordered (3 × 3)-iodine layer all appeared stable during rinsing with blank solution, free of I- and the Pt complex (PtCl42-).
High-resolution in situ and ex situ TEM studies on graphene formation and growth on Pt nanoparticles
Peng, Zhenmeng,Somodi, Ferenc,Helveg, Stig,Kisielowski, Christian,Specht, Petra,Bell, Alexis T.
, p. 22 - 29 (2012)
The formation of graphene layers on MgO-supported Pt nanoparticles was studied by both in situ and ex situ high-resolution transmission electron microscopy (HRTEM). The HRTEM images indicate that graphene sheets grow from steps in the surface of Pt nanoparticles. The subsequent morphology of the graphene sheets is a strong function of Pt particle size. For particles less than ～6 nm in diameter, the graphene sheets form nanotubes or move from the surface of Pt particles and accumulate on the MgO support. Complete particle envelopment by multiple graphene layers was only observed for particle greater than ～6 nm in diameter. The observed dependence of graphene morphology on Pt nanoparticle size and shape is associated with the strain energy generated between graphene layers during their growth and the overall free energy of the graphene-Pt system.
Fabrication and evaluation of platinum/diamond composite electrodes for electrocatalysis: Preliminary studies of the oxygen-reduction reaction
Wang, Jian,Swain, Greg M.
, p. E24-E32 (2003)
A catalytic electrode was prepared using a new electrically conducting and corrosion resistant carbon support material, boron-doped diamond. Fabrication of the composite electrode involves a three-step process: (i) continuous diamond thin-film deposition on a substrate, (ii) electrodeposition of Pt catalyst particles on the diamond surface, and (iii) short-term diamond deposition to entrap the metal particles into the surface microstructure. The process results in a conductive, morphologically, and microstructurally stable composite electrode containing metal particles of somewhat controlled composition, size, and catalytic activity. The metal catalyst particles were galvanostatically deposited from a K2PtCl6/HClO4 solution, with the metal particle size (50-350 nm) and distribution (～109 cm-2) being controlled by adjusting the galvanostatic deposition and secondary diamond-growth conditions. For a 300 s Pt deposition time, the estimated loading was 75.8 μg/cm2, assuming a 100% current efficiency. The composite electrode was extremely stable, both structurally and catalytically, during a 2 h polarization in 85% H3PO4 at 170°C and 0.1 A/cm2. The electrode's catalytic activity was evaluated using the O2 reduction reaction at room temperature in 0.1 M solutions of H3PO4, H2SO4, and HClO4. The kinetic parameters (Tafel slope and exchange current density) were obtained by cyclic voltammetry and were found to be comparable to those for a polycrystalline Pt electrode in the same media. Tafel slopes of -63 to -80 mV/dec were observed at low overpotentials, with the lowest slope in HClO4 and highest in H3PO4. The exchange current density ranged from 10-12 to 10-10 A/cm2, and increased in the order of H3PO4 2SO4 4. The potential advantages of the composite electrode, as compared with commercial sp2 carbon electrodes, are (i) the corrosion resistance of the diamond support, resulting in highly stable reaction centers at high potentials, current densities, and temperatures, and (ii) the fact that all of the catalyst particles are strongly anchored at the film surface and are not contained inside pores.
Temperature effect on the electrode kinetics of ethanol oxidation on Pd modified Pt electrodes and the estimation of intermediates formed in alkali medium
Mahapatra,Dutta,Datta
, p. 9097 - 9104 (2010)
Ethanol has been recognized as the ideal fuel for direct alcohol fuel cell (DAFC) systems due to its high energy density, non-toxicity and its bio-generation. However the complete conversion of ethanol to CO2 is still met with challenges, due t
In situ FTIR spectroscopic studies of (bi)sulfate adsorption on electrodes of Pt nanoparticles supported on different substrates
Zeng, Dong-Mei,Jiang, Yan-Xia,Zhou, Zhi-You,Su, Zhang-Fei,Sun, Shi-Gang
, p. 2065 - 2072 (2010)
Nanostructured Pt electrodes were prepared by electrodeposition of Pt nanoparticles on different substrates (GC, Pt and Au) under cyclic voltammetric conditions and with various number (n) of potential cycling, and were denoted as nm-Pt/S(n) (S = GC, Pt and Au). Adsorption of (bi)sulfate on the nm-Pt/S(n) was studied by in situ FTIR reflection spectroscopy. It has been revealed that the nanostructured Pt electrodes exhibit anomalous IR properties for (bi)sulfate adsorption regardless of the different reflectivity of substrate, i.e. the IR absorption of (bi)sulfate species adsorbed on all the nm-Pt/S(n) electrodes is significantly enhanced and the IR band direction is completely inverted in comparison with the same species adsorbed on a bulk Pt electrode. The two IR bands around 1200 and 1110 cm-1 attributed to adsorbed (bi)sulfate species are shifted linearly with increasing electrode potential, yielding Stark tuning rates (d over(ν, ?) / d ES) of 152.1 and 21.1 cm-1 V-1 on nm-Pt/GC(20), respectively. Along with increasing n, the Stark tuning rate of the IR band around 1200 cm-1 decreases quickly and declined to 7.6 cm-1 V-1 on nm-Pt/GC(80), while the Stark tuning rate of the IR band near 1100 cm-1 is fluctuated between 23.0 and 16.2 cm-1 V-1. It has determined that the enhancement of IR absorption of (bi)sulfate adsorbed on nanostructured Pt electrode is varied with substrate material and n, and a maximal 16-fold enhancement of the IR band near 1200 cm-1 has been measured on the nm-Pt/GC(30) electrode. The in situ FTIR studies illustrated that the adsorption of (bi)sulfate occurs mainly in the double layer potential region, and reaches a maximum around 0.80 V. The results demonstrated also that the competitive adsorption of CO and oxygen species can inhibit completely (bi)sulfate adsorption, which has evidenced a weak interaction of (bi)sulfate with nm-Pt/S(n) electrode surface.
Light-driven synthesis of hollow platinum nanospheres
Garcia, Robert M.,Song, Yujiang,Dorin, Rachel M.,Wang, Haorong,Li, Peng,Qiu, Yan,Van Swol, Frank,Shelnutt, John A.
, p. 2535 - 2537 (2008)
Hollow platinum nanospheres that are porous and have uniform shell thickness are prepared by templating platinum growth on polystyrene beads with an adsorbed porphyrin photocatalyst irradiated by visible light. The Royal Society of Chemistry.
Promotion effects in the oxidation of CO over zeolite-supported Pt nanoparticles
Visser, Tom,Nijhuis, T. Alexander,Van Der Eerden,Jenken, Karin,Ji, Yaying,Bras, Wim,Nikitenko, Sergei,Ikeda, Yasuo,Lepage, Muriel,Weckhuysen, Bert M.
, p. 3822 - 3831 (2005)
Well-defined Pt-nanoparticles with an average diameter of 1 nm supported on a series of zeolite Y samples containing different monovalent (H+, Na+, K+, Rb+, and Cs+) and divalent (Mg2+, Ca2+, Sr2+, and Ba2+) cations have been used as model systems to investigate the effect of promotor elements in the oxidation of CO in excess oxygen. Time-resolved infrared spectroscopy measurements allowed us to study the temperature-programmed desorption of CO from supported Pt nanoparticles to monitor the electronic changes in the local environment of adsorbed CO. It was found that the red shift of the linear Pt-coordinated Ca??O vibration compared to that of gas-phase CO increases with an increasing cation radius-to-charge ratio. In addition, a systematic shift from linear (L) to bridge (B) bonded Ca??O was observed for decreasing Lewis acidity, as expressed by the Kamlet-Taft parameter ?±. A decreasing ?± results in an increasing electron charge on the framework oxygen atoms and therefore an increasing electron charge on the supported Pt nanoparticles. This observation was confirmed with X-ray absorption spectroscopy, and the intensity of the experimental Pt atomic XAFS correlates with the Lewis acidity of the cation introduced. Furthermore, it was found that the CO coverage increases with increasing electron density on the Pt nanoparticles. This increasing electron density was found to result in an increased CO oxidation activity; i.e., the T50% for CO oxidation decreases with decreasing a. In other words, basic promotors facilitate the chemisorption of CO on the Pt particles. The most promoted CO oxidation catalyst is a Pt/K-Y sample, which has a T50%of 390 K and a L:B intensity ratio of 2.7. The obtained results provide guidelines to design improved CO oxidation catalysts. ? 2005 American Chemical Society.
Pt-Ru electrodeposited on gold from chloride electrolytes
Gavrilov,Petrii,Mukovnin,Smirnova,Levchenko,Tsirlina
, p. 2775 - 2784 (2007)
Voltammetric behavior of submicron-thick electrodeposited Pt-Ru on gold support is studied in sulfuric acid solution as a function of deposition potential and Pt:Ru ratio in chloride bath. In contrast to Pt-Ru, deposition of pure Ru is observed only at potentials of hydrogen evolution. The reason is found to be of kinetic nature, namely an inhibition of Ru deposition in presence of chloride. Chloride ions remain adsorbed on Ru at more negative potentials than on Pt and Au because of more negative ruthenium potential of zero free charge. Cu-UPD is applied to test the surface content of the oxidized Ru on pure Ru and various Pt-Ru surfaces. An enhancement of Ru oxohydroxides reduction in presence of Pt is observed. The electrocatalytic activity of Pt-Ru in respect to methanol oxidation correlates with the content of rechargeable surface Ru oxide. Ageing and 'training' of Pt-Ru electrodeposits under various modes is studied in order to determine the conditions of irreversible Ru oxidation. No manifestations of Ru dissolution from Pt-Ru electrodeposits in 0.5 M H2SO4 are found for anodic potential limits up to 1.1 V (RHE), in agreement with thermodynamic predictions. Electrodeposited Pt-Ru can be considered as a convenient model system for the study of Ru dissolution and crossover, as well as for determining the nature of the active surface species in the real composite catalysts for methanol oxidation.
Platinum concave nanocubes with high-index facets and their enhanced activity for oxygen reduction reaction
Yu, Taekyung,Kim, Do Youb,Zhang, Hui,Xia, Younan
, p. 2773 - 2777 (2011)
Many facets: A simple synthetic route, which is based on reduction in aqueous solution, results in Pt concave nanocubes (see picture) enclosed by high-index facets such as {510}, {720}, and {830}. The nanocrystals exhibit electrocatalytic activity (per un
Layered double hydroxides supported nanoplatinum catalyst for Suzuki coupling of aryl halides
Choudary, Boyapati M.,Roy, Moumita,Roy, Sarabindu,Kantam, M. Lakshmi
, p. 215 - 218 (2005)
Layered double hydroxides (LDH) supported nanoplatinum catalyst was prepared and employed for Suzuki cross coupling of aryl halides (iodides and bromides) with a broad range of arylboronic to afford the corresponding biaryls in good to excellent yields without using any external ligand. The catalyst is reused for several cycles with consistent activity.
Electrochemical properties of Pt coatings on Ni prepared by atomic layer deposition
Hoover, Robert R.,Tolmachev, Yuriy V.
, p. A37-A43 (2009)
Presented herein is an approach to fabrication of Pt coatings on non-noble metals with (sub)monolayer thickness. The Pt coatings were prepared using atomic layer deposition (ALD) in which Ni-disk substrate is exposed to MeCpPt Me3 and H2 in alternating cy
Support effects on the oxidation of ethanol at Pt nanoparticles
Moghaddam, Reza B.,Pickup, Peter G.
, p. 210 - 215 (2012)
The effects of metal oxide supports on ethanol oxidation have been investigated by drop coating Pt nanoparticles onto glassy carbon electrodes coated with thin layers of ruthenium oxide, tin oxide, a mixed Ru + Sn oxide, and onto an indium-tin oxide (ITO) electrode. All four oxide supports exhibited significant co-catalytic effects, with their effectiveness at low potentials increasing in the order Ru oxide ITO Ru + Sn oxide Sn oxide. However, at higher potentials (e.g. 0.4 V vs. SCE) currents were higher for Pt supported on Ru oxide or Ru + Sn oxide than on Sn oxide, revealing mechanistic differences between the roles of Ru and Sn oxide. Although Sn oxide produced very high initial activities, ITO and Ru + Sn oxide provided more stable performances.
Mohr, F.
, p. 137 - 137 (1873)
Area-selective atomic layer deposition of platinum on YSZ substrates using microcontact printed SAMs
Jiang, Xirong,Bent, Stacey F.
, p. D648-D656 (2007)
Using (methylcyclopentadienyl)trimethylplatinum (MeCpPtMe3) and oxygen as precursors, Pt has been deposited by atomic layer deposition (ALD) on the surfaces of yttria-stabilized zirconia (YSZ), a solid oxide electrolyte, as well as on oxide-covered silicon. Ex situ analyses have been carried out to examine the properties of both as-deposited and postannealed Pt films. X-ray photoelectron spectroscopy measurements demonstrate that there are no detectable impurities in the as-deposited Pt films, and four-point probe measurements show that the resistivity for a 30.2 nm film is as low as 18.3 μ cm. The use of area-selective ALD to deposit patterned Pt has also been investigated. By coating these same substrates with octadecyltrichlorosilane (ODTS) self-assembled monolayers (SAMs), Pt ALD can be successfully blocked. Furthermore, it is shown that by transferring the ODTS SAMs to the substrates by microcontact printing (μCP) using patterned stamps, platinum thin films are grown selectively on the SAM-free surface regions. Features with sizes as small as 2 μm have been deposited by this combined ALD-μCP method; the resolution is limited by the printed pattern and, likely, can be achieved at dimensions significantly smaller than a micrometer.
Addition of Hydroxide, Alkoxide, and Carboxylate Anions to Platinum-bonded Ethylene
Fanizzi, Francesco P.,Intini, Francesco P.,Maresca, Luciana,Natile, Giovanni,Gasparrini, Francesco
, p. 1019 - 1022 (1990)
The cation 2-C2H4)Cl(tmen)>+ (1) (tmen=N,N,N',N'-tetramethylethylenediamine) reacts with water and alcohol under basic conditions to give nucleophilic addition of hydroxide and alkoxide anions to ethylene and formation of (4) and respectively.Compound (4), either in solution or in the solid, undergoes a condensation reaction with formation of (5).Compound (1) reacts also with excess of acetate in water to give the ester complex Cl(tmen)> (6).Compound (6), in the solid state, slowly dissociates to acetate anion and cation (1), redissolution in chloroform restoring the original species.Compounds (3)-(6), dissolved in methanol, are transformed into (2).
Oxygen reduction at platinum modified gold electrodes
Van Brussel,Kokkinidis,Hubin,Buess-Herman
, p. 3909 - 3919 (2003)
The reduction of oxygen has been studied on polycrystalline gold electrodes modified by platinum deposited spontaneously from an aqueous K 2PtCl6 solution via the displacement of copper or lead adlayers. The change in the surface composition and morphology has been checked by XPS, AES and AFM data. The kinetic results have shown that such electrodes may present a higher catalytic activity compared to bulk platinum electrodes during a scan where the potential is made more positive and is thus clearly expressed by an hysteresis in the CV curves. The displacement of copper and lead deposits gave similar amplitudes of the hysteresis but the modified electrodes obtained via a lead deposit present a better stability upon cycling in acid solutions. The observed behaviour can be correlated to the modification of the M-OH formation and reduction on noble metals.
Seelheim, F.
, p. 479 (1879)
Comparison of extended x-ray absorption fine structure and Scherrer analysis of x-ray diffraction as methods for determining mean sizes of polydisperse nanoparticles
Calvin,Luo,Caragianis-Broadbridge,McGuinness,Anderson,Lehman,Wee,Morrison,Kurihara
, p. 1 - 3 (2005)
Curve fitting of extended x-ray absorption fine structure (EXAFS) spectra, transmission electron microscopy (TEM) imaging, and Scherrer analysis of x-ray diffraction (XRD) are compared as methods for determining the mean crystallite size in polydisperse s
X-ray structure and multinuclear NMR studies of platinum(II) complexes with 5-methyl-1,2,4-triazolo[1,5-a]pyrimidin-7(4H)-one
?akomska, Iwona,Wojtczak, Andrzej,Sitkowski, Jerzy,Kozerski, Lech,Sz?yk, Edward
, p. 803 - 810 (2007)
New dichloride platinum(II) complexes with 5-methyl-1,2,4-triazolo[1,5-a]pyrimidin-7(4H)-one (HmtpO) have been synthesized and characterized by thermal analysis, infrared and 1H, 13C, 15N, 195Pt NMR spectroscopy. X-ray crystal structures of cis-PtCl2(NH3)(HmtpO) (1) and cis-PtCl2(HmtpO)2 · 4H2O (2b) were determined to R = 0.0332 and R = 0.0802, respectively. In both complexes the Pt(II) ions have a square-planar geometry with two adjacent corners being occupied by two nitrogens of HmtpO molecules for 2b or NH3 and HmtpO molecules for 1, whereas the remaining adjacent corners are occupied by two chloride anions. Spectroscopic data confirm the square planar geometry with N(3) bonded HmtpO, S-bonded dimethylsulfoxide and two trans chloride anions for trans-PtCl2(dmso) · 4H2O (3).
Vapor-deposited Pt and Pd-Pt catalysts for solid acid fuel cells: Short range structure and interactions with the CsH2PO4 electrolyte
Papandrew, Alexander B.,John, Samuel St.,Elgammal, Ramez A.,Wilson, David L.,Atkinson, Robert W.,Lawton, Jamie S.,Arruda, Thomas M.,Zawodzinski, Thomas A.
, p. F464 - F469 (2016)
State-of-the-art cathodes for solid acid fuel cells (SAFCs) based on the crystalline electrolyte CsH2PO4 (CDP) are comprised of a proton-conducting CDP network coated by a vapor-deposited nanostructured catalyst. Pd-rich (85 at%Pd) Pt-Pd oxygen reduction catalysts vapor-deposited on CDP display both extraordinary activity for oxygen reduction and poor stability in cathodes for SAFCs operating at 250 °C. Similar catalysts with lower Pd content (57 at%Pd) are less active and more stable. Using X-ray absorption spectroscopy (XAS), we find that these catalysts are structurally similar and that structural variations are insufficient to explain the observed differences in activity. XAS and solid-state and solution nuclear magnetic resonance (NMR) also show that additional water-soluble chemical species are present in the Pd-rich electrode after fuel cell operation. We attribute the presence of these species to the reactivity of the Pd-rich catalyst with CsH2PO4 and suggest that these products are the cause of the observed deactivation.
Specific features of the formation of Pt(Cu) catalysts by galvanic displacement with carbon nanowalls used as support
Podlovchenko,Krivchenko,Maksimov,Gladysheva,Yashina,Evlashin,Pilevsky
, p. 137 - 144 (2012)
Microamounts of Cu are applied by the methods of electrodeposition (Cu ed) and magnetron sputtering (Cuspr) on a new carbon material, carbon nanowalls (CNW). The galvanic displacement (GD) of Cu ed and Cuspr in a PtCl42- solution (with 0.5 M H2SO4 as the supporting electrolyte) produces Pt(Cu)/CNW catalysts. The possibility of using open-circuit potential transients recorded in the course of GD for monitoring the surface layer composition is considered. The stable Pt(Cu)st samples are characterized by several methods (SEM, TEM, XPS, voltammetry, etc.). It is shown that Pt(Cu)st has structure of the core(Pt, Cu)-shell(Pt) type with the average atomic ratio Pt:Cu (%) ～ 57:43 for Cued and ～80:20 for Cuspr. The formation of the dense Pt shell is also confirmed by the data on the electrocatalytic activity of synthesized samples in the methanol oxidation reaction. The reasons for deviations in the properties of Pt(Cu) st/CNW samples formed from Cued and Cuspr are discussed. The high specific surfaces of the Pt(Cu)st/CNW catalyst obtained from Cued (>40 m2/g Pt) with the simultaneous decrease in the Pt content makes this material promising for using in the platinum-catalyzed processes (particularly, in fuel cells).
Scanning tunneling microscopy study of platinum deposited on graphite by metalorganic chemical vapor deposition
Ngo,Brandt,Williams,Kaesz
, p. 411 - 417 (1993)
The growth of thin Pt(111) films on highly oriented pyrolytic graphite (HOPG) by metalorganic chemical vapor deposition has been followed by scanning tunneling microscopy. Depositions were carried out on substrates held at 205°C and contacted with intersecting streams of H2 and of He saturated with (η5-C5H4CH3)Pt(CH3)3. The deposition was monitored by the appearance of methane in the product stream. Deposition initiated almost immediately, in contrast with earlier studies showing a significant induction period for deposition on glass. The deposits obtained after several minutes at 205°C consisted of Pt clusters with diameters ranging from 8 to 80 angstrom along with some very much larger Pt islands. The deposits were morphologically very rough with rather well defined facet orientation. The step heights of the terraces ranged from 20 to 54 angstrom. Oval shaped disks free of apparent dislocations were also observed. One of the larger crystallites investigated was 2074 × 1482 angstrom2 and 200 angstrom in height. The deposits were non-uniform throughout the deposition. The initial crystal growth under CVD was by island nucleation, followed by a growth mode that produced a random rough surface after the islands coalesced. At early stages the films are preferentially oriented with (111) crystallites parallel to the HOPG basal plane; further growth, however, leads to a poly-crystalline deposit.
Preferential CO oxidation promoted by the presence of H2 over K-Pt/Al2O3
Minemura, Yuji,Ito, Shin-Ichi,Miyao, Toshihiro,Naito, Shuichi,Tomishige, Keiichi,Kunimori, Kimio
, p. 1429 - 1431 (2005)
In preferential CO oxidation in H2-rich gas, K-Pt/Al 2O3 (K/Pt =10) was very effective in decreasing CO concentration below 10 ppm in the 375-410 K range, and the turnover frequency of the K-Pt/Al2O3
One-pot synthesis of PtSn bimetallic composites and their application as highly active catalysts for ethanol electrooxidation
Feng, Yue,Wang, Caiqin,Bin, Duan,Zhai, Chunyang,Ren, Fangfang,Yang, Ping,Du, Yukou
, p. 93 - 99 (2016)
PtSn nanoparticles with different molar ratio are fabricated by chemical reduction to form a relatively efficient catalyst for ethanol electrooxidation in an alkaline solution of KOH (1.0 m) containing C2H5OH (1.0 m). The surface composition and structure of the as-prepared catalysts are characterized by using scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and energy dispersive X-ray spectroscopy (EDX). Cyclic voltammogram (CV) and chronoamperometric (CA) measurements are used to evaluate the electrochemical activity and stability of the as-prepared catalysts. As the content of Sn in the catalysts changed, the catalysts showed different catalytic activity. The results indicate that the moderate addition of Sn can enhance the catalytic activity of Pt catalyst, and Pt3Sn1 displays the highest catalytic activity and stability among the as-synthesized PtSn nanoparticles during the electrooxidation of ethanol. Bimetallic PtSn electrocatalysts with different atomic ratios have been fabricated by a chemical reduction in a facile manner. Electrochemical measurements reveal that Pt3Sn1 catalysts exhibit the highest efficiency and stable electrocatalytic performance towards ethanol electrooxidation in an alkaline medium (see figure).
Catalytic oxidation of carbon monoxide over radiolytically prepared Pt nanoparticles supported on glass
Kapoor,Belapurkar,Mittal,Mukherjee
, p. 1654 - 1661 (2005)
Platinum nanoparticles have been prepared by radiolytic and chemical methods in the presence of stabilizer gelatin and SiO2 nanoparticles. The formation of Pt nanoparticles was confirmed using UV-vis absorption spectroscopy and transmission electron microscopy (TEM). The prepared particles were coated on the inner walls of the tubular pyrex reactor and tested for their catalytic activity for oxidation of CO. It was observed that Pt nanoparticles prepared in the presence of a stabilizer (gelatin) showed a higher tendency to adhere to the inner walls of the pyrex reactor as compared to that prepared in the presence of silica nanoparticles. The catalyst was found to be active at ≥150 °C giving CO2. Chemically reduced Pt nanoparticles stabilized on silica nanoparticles gave ～7% CO conversion per hour. However, radiolytically prepared Pt nanoparticles stabilized by gelatin gave ～10% conversion per hour. Catalytic activity of radiolytically prepared platinum catalyst, coated on the inner walls of the reactor, was evaluated as a function of CO concentration and reaction temperature. The rate of reaction increased with increase in reaction temperature and the activation energy for the reaction was found to be ～108.8 kJ mol-1. The rate of CO2 formation was almost constant (～1.5 × 10-4 mol dm -3 h-1) at constant O2 concentration (6.5 × 10-3 mol dm-3) with increase in CO concentration from 2 × 10-4 mol dm-3 to 3.25 × 10 -3 mol dm-3. The data indicate that catalytic oxidation of CO takes place by Eley-Rideal mechanism.
Asymmetrically strained hcp rhodium sublattice stabilized by 1D covalent boron chains as an efficient electrocatalyst
Li, Zhenyu,Ai, Xuan,Chen, Hui,Liang, Xiao,Li, Xiaotian,Wang, Dong,Zou, Xiaoxin
supporting information, p. 5075 - 5078 (2021/05/28)
Intermetallic rhodium boride (RhB) comprising an asymmetrically strained hcp Rh sublattice is synthesized. The covalent interaction of interstitial boron atoms is found to be the main contributor to the generation of asymmetric strains and the stabilization of the hcp Rh sublattice. In addition, RhB is identified as a hydrogen-evolving eletrocatalyst with Pt-like activity, because the Rh(d)-B(s,p) orbital hybridization induces an optimized electronic structure.
New perspective of a nano-metal preparation pathway based on the hexahydro-closo-hexaborate anion
Liu, Jun,Zhang, Haibo,Zhao, Xue
, p. 33444 - 33449 (2020/09/21)
Today, metal-based nanomaterials play an increasingly important role in the energy, environment, medical and health fields. In order to meet the needs of various fields, it is necessary to continuously develop advanced technologies for preparing metal-based materials. Inspired by previous research, the results of a proof-of-concept experiment show that the hexahydro-closo-hexaborate anion (closo-[B6H7]?) in the borane cluster family has properties similar to NaBH4.Closo-[B6H7]?can not only convert common precious metal ions such as Au3+, Pd2+, Pt4+and Ag+to the corresponding zero-valence state, but also convert some non-precious metals such as Cu2+and Ni2+to the zero-valent or oxidation state.Closo-[B6H7]?moderate reduction to cause rapid aggregation of metal-based materials is not easy compared with NaBH4. Compared withcloso-[B12H12]2?,closo-[B6H7]?achieves the conversion of Pt4+to Pt0under ambient conditions, and its reduction performance extends to non-precious metals. The excellent stability and easy modification characteristics determine the universality of thecloso-[B6H7]?reduction strategy for metal ions.
Synthesis, physico-chemical characterization and bioevaluation of Ni(II), Pd(II), and Pt(II) complexes with 1-(o-tolyl)biguanide: Antimicrobial and antitumor studies
Nu??, Ileana,Badea, Mihaela,Chifiriuc, Mariana Carmen,Bleotu, Coralia,Popa, Marcela,Daniliuc, Constantin-Gabriel,Olar, Rodica
, (2020/06/02)
New complexes of type [M(tbg)2]Cl2 [tbg = 1-(o-tolyl)biguanide; M = Ni(II), Pd(II), and Pt(II)] were synthesized and characterized to develop new biologically active compounds. The features of the complexes were assigned from microanalytical and thermal data. The NMR, FT-IR, and UV-Vis spectra were established by comparison with HtbgCl. All complexes exhibit a square-planar geometry resulting from the chelating behavior of tbg. The HtbgCl and [Ni(tbg)2]Cl2 complexes were fully characterized by single-crystal X-ray diffraction. The HtbgCl species crystallize in the monoclinic C2/c spatial group, while the Ni(II) complex adopts an orthorhombic Pna21 spatial group. The structure is stabilized by a complex hydrogen bonds network. The in vitro antimicrobial assays revealed improved antimicrobial activity for complexes in comparison with the ligand against both planktonic and biofilm embedded microbial cells. The most efficient compound, showing the largest spectrum of antimicrobial activity, including Gram-positive and Gram-negative bacteria, as well as fungal strains, in both planktonic and biofilm growth states was the Pd(II) complex, followed by the Pt(II) complex. The Pt(II) compound exhibited the most significant antiproliferative activity on the human cervical cancer SiHa cell line, inducing a cell cycle arrest in the G2/M phase.
