H2PtCl6 Research Articles

Synthesis and structure characterization of Pt(IV) and Cd(II) 1,10-phenanthroline complexes; fluorescence, antitumor and photocatalytic property

The room temperature addition of an aqueous solution of chloroplatinic acid hydrate or cadmium nitrate tetrahydrate to a mixture of an aqueous acetonitrile solution of 1,10-phenanthroline ligand (phen) and sodium azide affords new complexes of [Pt(N3)6Na2(phen)6], (1) and [Cd(phen)2(NO3)2], (2). The complexes 1, 2 were structurally characterized by elemental analysis, Fourier-transform infrared (FT-IR), Ultraviolet–visible (UV–vis), and nuclear magnetic resonance (NMR) spectroscopic techniques. The crystal structure of complexes 1, 2 was examined by single crystal X-ray diffraction. The complex 1 consists of two ionic complexes of [Pt(N3)6]2–and [Na(phen)3]+. The coordination geometry of Pt(IV) ion in complex 1 is distorted octahedral through six N atoms of the six terminal azide groups, while the sodium ion bonded to three phen ligand through six nitrogen atoms. In complex 2, phen and nitrate group act as bidentate ligands coordinating to Cd(II) through their nitrogen and oxygen atoms to form eight coordination. The two phen and nitrate ligands are coordinated to the cadmium in a cis geometry to each other. Three-dimensional supramolecular frameworks of complexes 1, 2 are produced by hydrogen bonding and π-π stacking interactions. The complex 1 was tested for cytotoxicity impact on two tumor cell lines: hepatocellular carcinoma HePG-2 and mammary gland breast cancer MCF-7 using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. The results indicate that complex 1 has strong activity on the two cancer cell lines HePG-2 and MCF-7. Also, complex 1 was screened for its antioxidant and anti-haemolytic activities. In addition, complex 2 was used as a heterogeneous catalyst for the degradation of Indigo carmine dye (IC) in the presence of H2O2 as oxidant. Additionally, the luminescence spectra of 1,10-phenanthroline ligand and complexes 1,2 were discussed.

Preparation of Platinum Nanostructures Directly Grown on Microporous Layer By an Electrodeposition Technique for a Commercial-Scale PEMFC

Proton exchange membrane fuel cells (PEMFC) have a lot of attention due to their low operating temperature and quick startup. Pt-based catalysts, usually used in the PEMFC electrodes, are the main contributor to the high cost. An electrodeposition technique that could significantly improve the deposition of platinum (Pt) nanostructures onto on carbon cloths was adopted in this study. The electrolyte used for electrodeposition was a mixed solution of 0.1 M sulfuric acid and Pt precursor chemical of 0.5 mM hexachloroplatinic acid (H2PtCl6·6H2O) to fabricate a 3D structural catalyst layer as an electrode used in proton exchange membrane fuel cell (PEMFC). Without using any catalyst supports, the catalyst nanostructure would enhance the catalytic activity area. In this study, the dimensions of the working electrode were 1, 9, and 25 cm2. The sizes of the Pt nanostructures are 100-300 nm in diameter. This new technique could further enhance the catalyst activities and lead to a significantly improved Pt uniformly distribution on the carbon clothes.

A Catalytic Carrier Gas Sensor Based on a Nanotube Array

To effectively monitor methane in coal mine environments, a new type of catalytic carrier gas sensor based on a nanotube array was designed and fabricated. The sensor consists of a catalytic carrier based on a nanotube array, a sensitive Pt electrode, leading wires made from Ag/Pd alloy, a standard two-pin tube shell, powder metallurgy sheets and other components. The metallurgical copper powder sheets make the sensor explosion-proof. The desired catalytic carrier based on a Al2O3 nanotube array was prepared by chemical deposition on a nanoporous carrier film. The sensitive Pt electrode was prepared by a thick-film printing process via impregnation with a chloroplatinic acid and palladium chloride solution to form the noble metal catalyst. The results show that for methane concentrations in the range of 0% to 3%, the measured output is approximately 73 5 mV, the response time is 6 seconds, and the recovery time is 5 seconds. When the CH4 concentration is in the range of 0~3.81%, the response voltage of the sensor and the concentration of CH4 exhibit a good linear relationship. The stability of the sensor was examined in a 2% CH4 environment, and the stability of the sensor drifted 0.15% after 60 days.

Influence of Boron, Tungsten and Molybdenum Modifiers on Zirconia Based Pt Catalyst for Glycerol Valorization.

The influence of boron, tungsten and molybdenum modifiers on zirconia-based Pt catalyst was studied for glycerol valorization. Zirconia modified supports were prepared by impregnation of ZrO2 with either boric, silicontungstic or phosphomolybdic acids to obtain supports with enhanced Brönsted acidic properties. The modified supports were subsequently impregnated with chloroplatinic acid to obtain Pt-based catalysts. Pt incorporation resulted in the increase in Lewis acidity of the solids, being more significant for the Pt//W/ZrO2 catalyst. Reduced Pt catalysts were tested for the liquid-phase glycerol hydrogenolysis, observing a synergistic effect between catalyst acid sites and metal function that proved to be crucial in glycerol hydrogenolysis. The Pt//W/ZrO2 catalyst was the most active catalyst in this reaction, being the only leading to 1,3-PDO (45% sel., 160 °C) while Pt//Mo/ZrO2 is the best option for 1,2-PDO (49% sel., 180 °C). Reusability studies carried out for Pt//W/ZrO2 showed that catalytic activity dropped after the first use, remaining constant for the second and subsequent ones. Selectivity to reaction products also changes during reuses. Therefore, the selectivity to 1,2 PDO increases in the first reuse in detriment to the selectivity to n-propanol whereas the selectivity to 1,3-PDO remains constant along the uses. This behavior could be associated to the lixiviation of W species and/or catalyst fouling during reaction runs.

Controlled Synthesis of Surfactant-Free Water-Dispersible Colloidal Platinum Nanoparticles by the Co4Cat Process.

The recently reported Co4Cat process is a synthesis method bearing ecological and economic benefits to prepare precious-metal nanoparticles (NPs) with optimized catalytic properties. In the Co4Cat process, a metal precursor (e.g., H2 PtCl6 ) is dissolved in an alkaline solution of a low-boiling-point solvent (methanol) and reduced to NPs at low temperature (<80 °C) without the use of surfactants. Here, the Co4Cat process to prepare Pt NPs is described in detail. The advantages of this new synthesis method for research and development but also industrial production are highlighted in a comparison with the popular "polyol" synthesis. The reduction of H2 PtCl6 from PtIV to PtII and further to Pt0 is followed by UV/Vis and XANES/EXAFS measurements. It is demonstrated how the synthesis can be accelerated, how size control is achieved, and how the colloidal dispersions can be stabilized without the use of surfactants. Despite being surfactant-free, the Pt NPs exhibit surprisingly long-term (up to 16 months) stability in water over a wide pH range (4-12) and in aqueous buffer solutions. The Co4Cat process is thus relevant to produce NPs for heterogeneous catalysis, electro-catalysis, or bio/medical applications.

Pt catalysts supported on lignin-based carbon dots for methanol electro-oxidation

Pt catalysts supported on lignin-based carbon dots are successfully prepared, and their catalytic performances for methanol electro-oxidation are investigated. Firstly, lignin-based carbon dots (Lg-CDs) are prepared by the acid etching of lignin carbonization products. Then, Pt catalysts supported on lignin-based carbon dots (Pt/Lg-CDs) are synthesized by the reduction of chloroplatinic acid in carbon dots solution. Although Pt/Lg-CDs catalysts aggregate obviously due to the deposition of Pt catalysts on the surface of Lg-CDs, the activity and stability of an optimal Pt/Lg-CDs-800 catalyst are still more outstanding than commercial Pt/C (40%Pt) and PtRu/C (30%Pt+15%Ru) catalysts for methanol electro-oxidation reaction (MOR) in acidic solutions. A large number of oxygen-containing groups on the surface of Lg-CDs-800 facilitate the uniform and stable deposition of Pt catalysts, and make the surface of more Pt catalysts expose to reaction system, thereby improving catalytic performance.

Hollow Pt skim-sandwiched Cu spheres supported on reduced graphene oxide-carbon nanotube architecture for efficient methanol electrooxidation

The disadvantages of high cost, easy poisoning and insufficient durability hinder platinum (Pt) application in direct methanol fuel cells. In this study, a hybrid of reduced graphene oxide/carbon nanotubes-supported hollow copper spheres (Cu/rGO@CNTs) is prepared by a one-step electrodeposition method. Then, the internal and external surfaces of hollow Cu spheres are coated with Pt skims to obtain a hollow bimetallic electrocatalyst (Pt/Cu/rGO@CNTs) through a simple galvanic replacement reaction by immersing Cu/rGO@CNTs in a chloroplatinic acid (H2PtCl6) solution. The three dimensional rGO@CNTs network structure benefit mass transport and electron transfer. Pt skims expose abundant active sites for electrocatalytic methanol oxidation reactions (MORs). Cu cores synergize Pt skims to enhance anti-poison ability. As a result, Pt/Cu/rGO@CNTs shows an excellent electrocatalytic activity for MORs with a robust tolerance of catalyst poisoning.

Pt-activated Ce4La6O17 nanocomposites for formaldehyde and carbon monoxide sensor at low operating temperature

In this paper, a cataluminescence (CTL) type formaldehyde (HCHO) and carbon monoxide (CO) gas sensor based on their cross sensibility on platinum (Pt) activated Ce4La6O17 nanocomposites at lower operating temperature than 150 °C was reported. The Ce4La6O17 nanocomposites were synthesized via sol-gel method. Pt was added into the composites by dipping the composites into the aqueous solution of chloroplatinic acid and calcined at 300 °C. The EDS spectrum and TEM images showed the constituents, distribution and particle size of the obtained composites. The sensing conditions were optimized, and the sensing properties were characterized. The linear ranges of CTL intensity versus analyte concentration was 0.2–54.5 ppm for HCHO and 1.2–67.0 ppm for CO. The limits of detection were 0.04 ppm for HCHO and 0.6 ppm for CO. The recoveries of 10 testing standard samples was 96.6%～103.2% for HCHO and 97.6%～103.5% for CO. These results indicated that nano-Pt/Ce4La6O17 would be a good candidate for fabricating practical CTL gas sensor for HCHO and CO.

Synthesis and Structure of Platinum Diethyl Sulfoxide Complexes

The reaction of tetraorganylphosphonium and tetraethylammonium chlorides with hexachloroplatinic acid hydrate in a mixture of acetonitrile and diethyl sulfoxide produced [Ph3PEt][PtCl5(deso-S)] and [Et4N][PtCl5(deso-S)] complexes containing tetrahedral tetraorganylphosphonium or tetraethylammonium cations and octahedral diethylsulfoxidopentachloroplatinate anions.

Platinum nano-flowers with controlled facet planted in titanium dioxide nanotube arrays bed and their high electro-catalytic activity

To better platinum's (Pt’s) electro-catalytic activity for oxidizing methanol, nano-flowers structured Pt catalysts with controlled facet had been planted onto titanium dioxide nanotube array (TNA) bed via a pulse electrodepositing method in an acid electrolyte containing chloroplatinic acid (H2PtCl6). The facet of Pt nano-flowers can be tuned as (111) or (100) by adding sulfuric acid (H2SO4) or hydrochloric acid (HCl) respectively into the precursor. It has been discovered that the nano-flower structured Pt catalysts with (111) facet generates a current density peak of 243.16 mA·mg−1(~2 times that of Pt catalysts with (200) facets) for catalytic oxidizing methanol in electrolyte containing 1 M methanol and 0.5 M H2SO4. In addition, the concentration of sulfuric acid in electrolyte has an effect on electrode's morphology, its electro-catalytic capability and stability. The mechanism of sulfuric acid anion for bettering Pt’s electro-catalytic activity had been comparatively investigated by replacing H2SO4 as HCl in precursor.

Characterization of Multinanoporous Pt-TiO&amp;lt;sub&amp;gt;2&amp;lt;/sub&amp;gt; Thin Films Fabricated by a Three-Step Electrochemical Technique

In the present investigation, a three-step electrochemical as a novel method has been applied to fabricate multinanoporous thin film electrodes of pure TiO₂ and the doped Pt-TiO₂ (of approximately 15 nm) from the titanium sheet using sulfuric acid as electrolyte and chloroplatinic acid as platinum dopant precursor. Characterization techniques so far discussed in this work revealed that the fabricated products corresponded to pure TiO₂ and to the doped Pt-TiO₂ respectively. The prepared Pt-TiO₂ thin film electrodes have photoresponse to visible light, which indicates a new possibility for improving intrinsic TiO₂ photoresponse.

Electrochemical Biosensor Based on Dewdrop-Like Platinum Nanoparticles-Decorated Silver Nanoflowers Nanocomposites for H2O2 and Glucose Detection

A novel electrochemical detection platform was constructed based on dewdrop-like platinum nanoparticles-decorated silver nanoflowers nanocomposites coated with bovine serum albumin (AgNFs-Pt@BSA), which were synthesized through replacement reaction between chloroplatinic acid and AgNFs. As expected, in final obtained AgNFs-Pt@BSA nanocomposites, the petal structures of AgNFs with broad surface areas led to a high electron conductivity; Pt nanoparticles favorably enhanced the electrocatalytic ability toward hydrogen peroxide (H2O2); bovine serum albumin (BSA) coated around AgNFs-Pt provided numerous functional groups (especially -NH2). Inspired by above characteristics, a remarkable glucose biosensor could be assembled through crosslinking glucose oxidase with AgNFs-Pt@BSA via glutaraldehyde (AgNFs-Pt@BSA/GA/GOD). The high electrochemical responses were exhibited linearly in a wide concentrate range of glucose from 1 to 14 mM with a low detection limit of 0.3 mM at a signal-to-noise ratio of 3. Furthermore, with the advantages of favorable selectivity, excellent reproducibility and durable stability, here prepared electrochemical sensor showed promising analytical performance in the detection of glucose in human serum samples. All satisfied results provided a considerable direction of advance and prospect for the clinical applications of human blood glucose detection in the coming future.

Comparative Study of Different Electrochemical Techniques for the Preparation of Supported Pt-Ru Catalysts

Bimetallic Pt-Ru particles supported on glassy carbon rods were synthesized by simultaneous electrochemical deposition. Pt-Ru alloy particles were deposited from a dilute aqueous acid solution of chloroplatinic acid and ruthenium trichloride by different electrochemical techniques: (i) coulostatic deposition at constant potential; (ii) double potentiostatic steps; and (iii) multiple cycles of potentiostatic pulses. It was found that particle size distribution, and the morphology and composition of the deposits strongly depend on the deposition method. Scanning electron microscopy images showed the presence of agglomerates with diameters in the submicrometre scale composed of nano-sized particles. The catalysts prepared by multiple cycles of potentiostatic pulses exhibited better activity for methanol oxidation and enhanced tolerance to CO poisoning compared with those prepared by the other techniques. This behaviour could be associated with the structure containing a high number of defects of the particles and a higher ruthenium content in the solid solution.

Tailoring Electrocatalytic Properties of Pt Nanoparticles Grown on Ti3C2TX MXene Surface

In this work, the spontaneous and NaBH4-induced reduction of chloroplatinic acid on the surface of Ti3C2TX MXene was investigated to synthesize a hybrid PtNP-decorated MXene nanomaterial (MX-Pt) with potential as hydrogen evolution (HER) or oxygen reduction reaction (ORR) catalyst properties. The initial Pt concentration, reduction time and presence of additional reducing agents were varied, and as-synthesized nanocomposites were characterized thoroughly by XRD, EDX, SEM and XPS analysis and by electrochemical methods. Composites containing 14 wt% Pt showed HER with an onset potential of −75.9 mV and a current density of −10 mA cm−2 achieved at −226 mV. The spontaneous deposition of PtNPs on MXene improved the electrocatalytic properties over using an external reducing agent to form PtNP, which was explained based on the different rates of oxidation of Ti in the initial MXene support. Furthermore, good stability of the electrode modified by the MX-Pt was achieved without any polymeric binder and the HER reaction achieved only a negligible decrease over 3 000 potentiodynamic cycles.

Реакции хлоридов тетраорганилфосфония и тетраэтиламмония с гидратом гексахлороплати-новодородной кислоты в растворах ацетонитрила и диэтилсульфоксида

Реакции хлоридов тетраорганилфосфония и тетраэтиламмония с гидратом гексахлороплати-новодородной кислоты в растворах ацетонитрила и диэтилсульфоксида

Prussian Blue Microcrystals with Morphology Evolution as a High-Performance Photo-Fenton Catalyst for Degradation of Organic Pollutants.

The morphology-dependent property of crystal materials has aroused extensive attention and raised high requirements for subtly tailoring the morphology of micro-/nanocrystals. Herein, we develop an in situ etching method for preparation of Prussian blue (PB) microcrystals with morphology evolution by progressively increasing the concentration of chloroplatinic acid in the reaction system. These PB microcrystals with controllable morphologies are employed as photo-Fenton reagents to degrade organic pollutants. PB hexapods (PB-hpds) and PB hexapod stars present superior catalytic performance to pristine PB microcubes and other PB intermediates with truncated corners or edges because of their high specific surface areas and adequate exposure of FeIII-NC coordination active sites. In the reusability test, the reused PB-hpds present more efficient catalytic performance for rhodamine B decomposition compared with the pristine catalyst. According to more investigations, the reasonable mechanism is proposed that FeIII-NC exhibits higher catalytic activity than FeII-CN in the specific coordination environment. The increased content of surface FeIII-NC coordination active sites is the key factor in accelerating the decomposition of H2O2 and enhancing the photo-Fenton performance of PB-hpds. Several operating parameters including catalyst dosage, H2O2 concentration, pH value, and reaction temperature are evaluated in detail. Classical quenching experiments and electron paramagnetic resonance measurements further reveal that HO• should be responsible for high performance of catalysts. This work will be significant for tailoring the morphology of the materials and arousing more attention to enhance the stability and reusability of catalysts.

Fabrication of a patterned Pt counter electrode for dye-sensitized solar cells using neutralized H2PtCl6·6H2O paste

Patterned platinum counter electrodes for dye-sensitized solar cells (DSSCs) were formed using neutralized platinum precursor pastes and a screen-printing method. Hydrogen hexachloroplatinate (IV) hexahydrate was used as a platinum precursor. Hexylene glycol was used as a solvent for the precursor and lithium hydroxide dissolved in ethylene glycol monomethyl ether was used as a neutralizing agent to prepare neutralized pastes. The results suggest that approximation of the energy from dipolar intermolecular forces between molecules, as represented by one of the Hansen solubility parameters, is an important factor for avoiding liquid–liquid phase separation in this case. The surface of the platinum layers exhibited a two-dimensional structure of fine particles (5–10 nm) with a ∼99.5% coverage rate. Consequently, the photoelectric conversion performance of DSSCs fabricated using the printed platinum counter electrodes was nearly equivalent to that fabricated using a sputtered platinum counter electrode, which is often used as a reference electrode.

Treatment of Volatile Organic Compounds with a Pt/Co3O4‐CeO2 Catalyst

AbstractFor emission control of volatile organic compounds (VOC), e.g., in the painting and printing industries, conventional Pt/Al2O3 and Co3O4‐CeO2 catalysts are used. On the Pt/Al2O3 catalyst, aromatic hydrocarbons containing a benzene ring such as toluene can be oxidized at a lower complete oxidation temperature than on Co3O4‐CeO2, under typical treatment conditions. However, ethyl acetate and isopropyl alcohol can be oxidized at a lower complete oxidation temperature on Co3O4‐CeO2 than on Pt/Al2O3. In this study, platinum was directly supported on Co3O4‐CeO2. Using chloroplatinic acid, the platinum cohered and the catalytic activity did not improve. But when the platinum was supported using platinum colloid coated with dispersant, high‐dispersion support of the platinum on the Co3O4‐CeO2 surface was achieved, and toluene, ethyl acetate, and isopropyl alcohol could be oxidized at less than 250 °C.

Soluble Pt Nanoparticles Stabilized by a Tris‐imidazolium Tetrafluoroborate as Efficient and Recyclable Catalyst for the Stereoselective Hydrosilylation of Alkynes

AbstractSoluble platinum nanoparticles (Pt NPs) have been prepared by a two‐step procedure involving the reduction of chloroplatinic acid with ethylene glycol/NaOH at 160 °C and subsequent treatment with a THF solution of a tris‐imidazolium tetrafluoroborate at room temperature. The isolated Pt NPs have been characterized by transmission electron microscopy (TEM), high‐resolution transmission electron microscopy (HRTEM), electron diffraction (ED), Energy‐Dispersive X‐ray Spectroscopy (EDS), and elemental analysis. They proved to be efficient and recoverable catalysts for the stereoselective hydrosilylation of internal alkynes in the presence and absence of solvent.

Construction of non-enzymatic sensor based on porous carbon matrix loaded with Pt and Co nanoparticles for real-time monitoring of cellular superoxide anions

Quantification of superoxide anions (O2−) is of great significance for the pathological research of many diseases. In this work, a non-enzymatic electrochemical sensor for superoxide sensing was fabricated on the basis of metal-organic frameworks (MOFs)-derived porous carbon matrix loaded with Pt and Co nanoparticles (denoted as Pt-Co-PC). Zeolitic imidazolate framework-67 (ZIF-67) was utilized as the precursor through a one-step calcination under N2 atmosphere to prepare cobalt nanoparticles-porous carbon composites (denoted as Co-PC). Pt-Co-PC was then obtained by using a facile galvanic replacement procedure with Co-PC and chloroplatinic acid solution. Furthermore, the home-made screen printed gold electrodes (SPGEs) were used to immobilize the as-synthesized materials, constructing Pt-Co-PC modified electrochemical sensors. The recommended Pt-Co-PC/SPGE sensors exhibit excellent electrochemical performance for the detection of O2− with an extremely low detection limit of 0.118 μM (S/N = 3) and a high sensitivity of 6.218 × 10−4 mA μM−1 cm−2. Meanwhile, the proposed sensors possess superior reproducibility and stability. More importantly, our sensors have successfully captured the electrochemical signals of O2− released from Hela cells, which means the fabricated sensors have potential application of monitoring O2− in pathological and biological fields.