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1.
WO 3 has been prepared via thermal decomposition of ammonium paratungstate. The obtained oxide has been characterized by X‐ray diffraction (XRD) spectroscopy. The particle size was found to increase with increasing calcination temperature. The modified Pt/WO 3/GC electrode has been prepared and characterized using various analytical and electrochemical techniques. The electrochemical oxidation of ethylene glycol (EG) on the modified electrode was investigated and compared with that of a Pt/GC electrode in acidic solution. The presence of WO 3 enhanced the electrode activity towards EG oxidation. The enhancement factor was found to depend on the ratio of WO 3:Pt as well as on the calcination temperature during WO 3 preparation 相似文献
2.
Polycrystalline platinum decorated by WO 3 nanoparticles (WO 3/Pt pc) is used as a model electrode to gain insights into the enhanced tolerance to carbon monoxide (CO) observed on such composite materials. Bifunctional-type reactions involving WO 3 and Pt active sites are observed, such as hydrogen spill-over or the electrooxidation of CO molecules adsorbed on Pt sites neighboring the WO 3 nanoparticles. The resulting CO ad-free Pt sites are active for the hydrogen oxidation reaction (HOR), thereby enhancing the HOR activity for WO 3/Pt pc electrode relatively to bare Pt pc in 300 ppm CO/H 2 saturated HClO 4 electrolyte. However, this bifunctional effect occurs exclusively for CO molecules weakly adsorbed on Pt, i.e. only for a small fraction of the CO ad fully covering the Pt surface. 相似文献
3.
采用浸渍沉淀法制备出WO 3-碳纳米管(WO 3-CNTs)纳米复合材料, 微波辅助乙二醇法在其表面负载活性成分Pt, 得到纳米Pt/WO 3-CNTs 催化剂. 采用X射线衍射(XRD), 透射电子显微镜(TEM)和X射线光电子能谱(XPS)等测试手段对催化剂的结构和形貌进行表征, 结果表明Pt 纳米粒子为面心立方晶体结构, 粒径大小在3-5 nm之间, 均匀地分布在WO 3-CNTs 纳米复合材料表面, 同时发现催化剂中的Pt 主要以金属态的形式存在. 采用循环伏安和计时电流法研究了在酸性溶液中Pt/WO 3-CNTs 催化剂对甲醇的电催化氧化性能, 结果表明Pt/WO 3-CNTs 催化剂比用硝酸处理的碳纳米管载铂催化剂(Pt/CNTs)对甲醇呈现出更高的电催化氧化活性和抗CO中毒性能. 相似文献
4.
Oxygen activation plays a crucial role in many important chemical reactions such as oxidation of organic compounds and oxygen reduction. For developing highly active materials for oxygen activation, herein, we report an atomically dispersed Pt on WO 3 nanoplates stabilized by in situ formed amorphous H 2WO 4 out‐layer and the mechanism for activating molecular oxygen. Experimental and theoretical studies demonstrate that the isolated Pt atoms coordinated with oxygen atoms from [WO 6] and water of H 2WO 4, consequently leading to optimized surface electronic configuration and strong metal–support interaction (SMSI). In exemplified reactions of butanone oxidation sensing and oxygen reduction, the atomic Pt/WO 3 hybrid exhibits superior activity than those of Pt nanoclusters/WO 3 and bare WO 3 as well as enhanced long‐term durability. This work will provide insight into the origin of activity and stability for atomically dispersed materials, thus promoting the development of highly efficient and durable single atom‐based catalysts. 相似文献
5.
We report electrochromic properties of WO 3 in Au–WO 3 and Pt–WO 3 nanostructure thin-film electrodes prepared by co-sputtering deposition method. The nanostructure electrodes consisted of Au or Pt metallic nanophase and a tungsten oxidative phase, indicating the formation of crystalline metallic nanophases in the amorphous oxide matrix. In particular, due to metallic nanophases, the modified electrochromic properties of WO 3 were observed in the Au–WO 3 and Pt–WO 3. The nanostructure electrodes showed a reverse optical modulation with respect to applied potentials in H 2SO 4 solution compared to that of pure WO 3 electrode. However, due to an excellent electrocatalytic activity of platinum for methanol electrooxidation at 25 °C, the electrochromism of the Pt–WO 3 in contrast with that of the Au–WO 3 was affected by the potentials for methanol electrooxidation in 2 M CH 3OH and 0.5 M H 2SO 4. 相似文献
6.
以聚二烯丙基二甲基胺盐酸盐(PDDA)为连接剂,采用原位自组装方式将MoO3和WO3负载到碳纳米管(CNTs)上,然后通过乙二醇还原法负载Pt纳米颗粒,得到Pt纳米颗粒均匀分布的Pt/MoO3-WO3/CNTs催化剂.当氧化物总量控制在10 wt%,MoO3与WO3摩尔比为1:0.5时,Pt/MoO3-WO3/CNTs催化剂催化甲醇氧化活性最高,甲醇氧化峰电流If高达835 A/gPt.WO3和MoO3的加入提高了催化剂的甲醇氧化活性、抗CO中毒能力和稳定性,使得Pt/MoO3-WO3/CNTs催化剂表现出优异的甲醇电催化氧化性能. 相似文献
7.
In this paper, a new two-dimensional (2D)/2D composite of Bi 2WO 6/MoS 2 was facile synthesized, and then was used as supporting material for depositing Pt nanoparticles. The as-synthesized Pt-Bi 2WO 6/MoS 2 was extended into photo-assisted electrocatalytic oxidation of methanol, which is a model anode reaction for direct methanol fuel cell. Compare with traditional electrocatalytic process, Pt-Bi 2WO 6/MoS 2 displays 1.5 times enhanced electrocatalytic performance on methanol oxidation with assistance of visible light irradiation and 2.2 times for commercial Pt/C. Besides, from the results of chronoamperometric and chronopotentiometry experiments, the stability of Pt-Bi 2WO 6/MoS 2 electrode is clearly improved under visible light irradiation. The synergistic effects of photo- and electro-catalytic in the heterojunction of Pt-Bi 2WO 6/MoS 2 in favor of the above enhancement. This research gives more insights in the fields of photo-assisted traditional electrocatalytic application by constructing of semiconductor heterojunction carrier. 相似文献
8.
We have shown that additions of Pt(Pd) and Cs + to WO 3 significantly increase its specific surface area and catalytic activity in H 2 oxidation. After reduction, the promoted specimens contain the phases WO 3, WO 2.9, H xWO 3; and in the case of Cs + additions, Cs xWO 3. According to X-ray photoelectron spectroscopy (XPS), the Pt and Pd have an oxidation state close to 0, while tungsten has a +5 oxidation state. The W:O ratio indicates the content of oxygen vacancies in the surface layer. The data are explained taking into account hydrogen spillover from Pt(Pd) to the support.__________Translated from Teoreticheskaya i Eksperimental’naya Khimiya, Vol. 41, No. 2, pp. 126–129, March– April, 2005. 相似文献
9.
A hybrid photocatalyst was prepared from visible light-responsive Pt/WO 3 and siliceous mordenite (MOR) zeolite by simple impregnation with an aqueous solution of (NH 4) 10W 12O 41·5H 2O. Unmodified Pt/WO 3 had low photocatalytic activity in gas phase oxidation of acetaldehyde because of its low surface area (3–5 m 2/g). In contrast, the Pt/WO 3–MOR had higher photocatalytic activity under focused sunlight and Xe lamp irradiation. Pt/WO 3–MOR with low WO 3 content (<20 wt%) adsorbed sufficient acetaldehyde, but absorption of light in the visible region was low. The optimum zeolite content enhancing the photocatalytic activity of Pt/WO 3 was estimated to be 30–50 % ( w/ w). Adsorption of the gaseous reactants and the efficiency of absorption of incident light are both important aspects of high photocatalytic activity. 相似文献
10.
Electroplating of WO 3-Pt has been carried out using a suitable plating bath solution and optimum working conditions. X-ray and SEM studies of the deposit reveal a smooth and uniform distribution of micro-particles on the surface. New phases of the plated material appear on heat treatment. The electrocatalytic activity of the WO 3-Pt co-deposit is considerably higher than for platinum alone. WO 3 in the WO 3-Pt co-deposit reduces the retardation effect of methanol oxidation by the reaction intermediate observed in the case of Pt alone. WO 3-Pt co-deposits exhibit low overpotential for methanol oxidation in both acidic and alkaline media at low temperature and have good corrosion resistance in electrolytic media. The electrochemical parameters for methanol oxidation of these co-deposits depend on trace amounts of the platinum, heat treatment and the microstructure of the coating. 相似文献
11.
The role of the oxidation state of a platinum polycrystalline surface in the electrocatalytic oxidation of C 1 to C 4 primary alcohols has been studied by using electrochemical techniques, in situ FTIR spectroscopy and X-ray photoelectron spectroscopy. The results revealed that the oxidation state of the Pt surface plays a key role in the oxidation of primary alcohols, and demonstrated that the oxidation of C 1 to C 4 primary alcohols on a Pt electrode is controlled by the formation of surface oxides on the Pt electrode at different potentials. It was found that the dependence of the reaction process on the oxidation states of the platinum surface yielded similar features in the cyclic voltammogram for oxidation of different primary alcohols at a Pt electrode. According to the effects in the oxidation of primary alcohols, the surface oxides of platinum may be classified as active and poison species. The Pt surface oxides of higher oxidation states (Pt(OH) 3 and PtO 2) formed at potentials above 1.0 V (SCE) were identified as poison species, while other lower oxidation states of Pt surface oxides such as PtOH, Pt(OH) 2 and PtO may be identified as the possible active species for primary alcohol oxidation. 相似文献
12.
Single‐atom catalysts (SACs) have attracted growing attention because they maximize the number of active sites, with unpredictable catalytic activity. Despite numerous studies on SACs, there is little research on the support, which is essential to understanding SAC. Herein, we systematically investigated the influence of the support on the performance of the SAC by comparing with single‐atom Pt supported on carbon (Pt SA/C) and Pt nanoparticles supported on WO 3?x (Pt NP/WO 3?x). The results revealed that the support effect was maximized for atomically dispersed Pt supported on WO 3?x (Pt SA/WO 3?x). The Pt SA/WO 3?x exhibited a higher degree of hydrogen spillover from Pt atoms to WO 3?x at the interface, compared with Pt NP/WO 3?x, which drastically enhanced Pt mass activity for hydrogen evolution (up to 10 times). This strategy provides a new framework for enhancing catalytic activity for HER, by reducing noble metal usage in the field of SACs. 相似文献
13.
We have shown that WO 3 and MoO 3 with Pt or Pd additives exhibit high catalytic activity in the reaction of H 2 oxidation. In the temperature range 313 K to 353 K, we have studied the kinetic behavior of the reaction on 0.1 mass % Pt(Pd)/WO 3 and Pt(Pd)/MoO 3 samples. We have established that the kinetics of H 2 oxidation on these catalysts correspond to an Eley - Rideal mechanism.
__________
Translated from Teoreticheskaya i Eksperimental'naya Khimiya, Vol. 41, No. 5, pp. 313–316, September–October, 2005. 相似文献
14.
采用表面修饰技术将碳纳米管(CNT)表面羧基化, 通过羧基将钨离子基团修饰到碳纳米管的外表面, 再通过高温焙烧处理将钨离子基团氧化成WO 3, 成功合成了纳米WO 3/CNT复合物, 进一步还原Pt 的前驱体而得到Pt-WO 3/CNT复合催化剂. 采用X射线粉末衍射(XRD)和透射电镜(TEM)对样品的形貌和晶型结构进行了表征, 结果表明, Pt纳米粒子为面心立方晶体结构, 均匀地分布在WO 3修饰的碳纳米管表面. 采用循环伏安(CV)和计时电流法研究了在酸性溶液中Pt-WO 3/CNT催化剂对甲醇的电催化氧化活性, 结果表明WO 3修饰的碳纳米管载铂催化剂比用混酸处理的碳纳米管载铂催化剂对甲醇呈现出更高的电催化氧化活性和更好的稳定性. 相似文献
15.
A comparative electrooxidation of Eg in the alkaline solution was investigated over Pt, Pd and Au nanoparticle-modified carbon-ceramic electrode. The kinetic parameters of Eg oxidation, i.e., Tafel slope and activation energy ( E a), were determined on the modified electrodes. The lowest E a value of 8.9 kJ mol ?1 was calculated on Pt|CCE. In continuation, the reaction orders with respect to the Eg and NaOH concentrations on Pd|CCE were found to be 0.4–0.2 and 0.6, respectively. An adsorption equilibrium constant (b) of 22.36 M ?1 and the adsorption Gibbs energy change (Δ G°) of ?7.7 kJ mol ?1 were obtained on Pd|CCE. The chronopotentiometry (CP) and chronoamperometry (CA) results showed that Pd|CCE and then Au|CCE have better performance stability than Pt|CCE for Eg electrooxidation. Additionally, the electrochemical impedance spectroscopy (EIS) suggested faster electron-transfer kinetics on Pt than that on the Pd and Au electrocatalysts. 相似文献
16.
The kinetics of oxygen isotope exchange between gas-phase oxygen and the electrochemical cell O 2, Pt | ZrO 2 + 10 mol % Y 2O 3 (YSZ) | Pt, O 2 with applied potential difference (Δ U = ±1.2 V) is studied in the temperature range of 600–800°С and the oxygen pressure interval of 3–13 kPa. An original design of a vacuum electrochemical cell with the separated gas space is put forward for studying how the potential difference on the electrochemical cell influences the kinetics of interaction of gas-phase oxygen with the gas electrode O 2, Pt | YSZ in the electrochemical cell. It is shown that the oxygen interphase exchange rate is the higher the more negative the charge on the electrode studied; moreover, the mechanism of gas-phase oxygen exchange with the gas electrode O 2, Pt | YSZ in the electrochemical cell depends fundamentally on the electrode charge sign. The possible reasons for the revealed differences are discussed; the corresponding models are proposed. 相似文献
17.
Photoelectrochemical (PEC) performance of WO 3 photoanodes for water splitting is heavily influenced by the orientation of crystal facets. In this work, mono-particle-layer electrodes, assembled by particulate WO 3 square plates with highly uniform alignment along the (002) facet, improved PEC water oxidation kinetics and stability. Photo-deposition of Au along the cracks formed on the surface of the plates, which are the edges of {110} facets, was found to further enhance electron collection efficiency. Combination of these two strategies allowed the facet-engineered WO 3 electrode to produce significantly higher efficiencies in charge separation and transfer than the electrode prepared without facet orientation. This work has provided a facile route for fabricating a structurally designed WO 3 photoelectrode, which is also applicable to other regularly shaped semiconductor photocatalysts with anisotropic charge migration. 相似文献
18.
通过循环伏安扫描法制备了PMo 12修饰Pt/Pt电极,并研究了该修饰电极在硫酸溶液中的电化学行为。研究结果表明:虽然磷钼酸具有较大的分子尺寸,但在Pt/Pt电极上仍能发生吸附作用,并且由于PMo 12在电极上的吸附,降低了Pt/Pt电极上氢区和氧区的荷电量,另外在0.02V左右还观察到磷钼酸的氧化-还原峰。通过稳态极化曲线和循环伏安曲线研究了PMo 12修饰Pt/Pt电极对甲醇氧化的电催化作用。测试结果表明:PMo 12修饰铂基电极不但对甲醇的电氧化具有较高的活性,而且还有一定的抗CO中毒性。该修饰电极还具有较高的稳定性。 相似文献
19.
The electrochemical behavior of irreversibly adsorbed antimony on a Pt(110) electrode (Pt(110)/Sb) with various coverages was studied using cyclic voltammetry. The kinetics of HCOOH oxidation via reactive intermediates on Pt(110)/Sb were investigated quantitatively by employing the potential step technique and in situ FTIR spectroscopy. The results demonstrated that Sb adatoms were stable on Pt(110) when the electrode potential was below 0.45 V (SCE). It has been revealed that the dissociative adsorption of formic acid can be inhibited by the presence of Sb ad on the Pt(110) surface. The electrocatalytic effects of Sb ad towards HCOOH oxidation consist in a negative shift of the oxidation potential (about 350 mV) and the enhancement of the oxidation current. Based on the data processing method of integration transform developed in our previous papers, the kinetics of HCOOH oxidation on Pt(110)/Sb electrodes of different θSb have been investigated quantitatively, and both the rate constant kf and the transfer coefficient β were determined and reported. 相似文献
20.
The hypochlorous acid (HCIO) was synthesized from seawater by the Pt/WO3 photocatalyst under visible-light irradiation. The effect of WO3 morphology and Pt loading on the performance of the composite photocatalyst for the production of HCIO has been studied in detail. The study found that among the series of materials, hollow WO3 microspheres with a diameter of about 3 μm loaded with 1.0 wt% Pt have the best HCIO production performance. Over it, 14.52 μM of HClO (1.24 mg/L of free chlorine) was accumulated in 0.5 M NaCl solution after 2 h of visible-light photoirradiation. What is more, the concentration of HClO can reach 4.34 μM (0.354 mg/L free chlorine) in natural seawater for 1 h using this Pt/WO3 photocatalyst. Under visible-light irradiation, the Pt/WO3 photocatalyst has a good broad-spectrum antibacterial activity and the activity of inhibiting marine fouling algae. The Pt/WO3 photocatalyst has high stability and reusability. All these characteristics are conducive to the application in the field of marine antifouling. Moreover, the photocatalytic reaction mechanism was evaluated by studying the photoelectrochemical properties of Pt/WO3/FTO. This research provides a new strategy for replacing the traditional electrolytic marine antifouling system with the visible-light-catalyzed HClO production system. 相似文献
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