A facile chemical strategy for the one-step synthesis of platinum nanoparticles (Pt NPs) is demonstrated in this paper. Pt nanoparticles were prepared using chemical reduction in NaBH4 and were capped in a polyvinyl alcohol (PVA) colloidal suspension. The morphology and structure of as-synthesized Pt nanoparticles are characterized by UV–Vis spectroscopy, X-ray diffraction (XRD) and transmission electron microscopy (TEM). The results indicated that the Pt nanoparticles with a narrow size distribution (2–4 nm) werehighly crystalline in nature. In addition, the electrochemical properties and the electrocatalytic activities of Pt nanoparticles modified glassy carbon electrode (GC) were characterized by cyclic voltammetry (CV). The experiments yielded evidence that Pt nanoparticles facilitated hydrogen peroxide reduction, and exhibited favorable electrooxidation activity towards NADH and methanol, showing excellent catalytic activity, and holding a good promise in catalytic and bioanalytical applications.

IIn this work we report a facile and green approach to synthesis of graphene nanosheets(GNS) supported Pt nanoparticles (Pt/GNS),in which graphene acts as a high surface area and conductive host for Pt nanoparticles for oxygen reduction reaction in fuel cells. Several phytochemicals extracted from different natural leaves of plants are employed as green and eco-friendly reducing agents in the synthesis of various silver, gold, platinum, and copper nanoparticles. In this study, Cherry leaf extracts were employed as a green reducing agent to reduce graphene oxide and Pt nanoparticles. The prepared Pt/GNS exhibits greatly enhanced electrochemical performance than commercial (ElectroChem Pt/C). These are attributed to the much graphitized degree of GNS in comparison to carbon black and the improved Pt-carbon interaction in Pt/GNS,high surface area and electrical conductivity of graphene support in Pt/GNS.

Heterostructure Pt/Bi2MoO6nanocomposites containing different weight contents of Pt nanoparti-cles were successfully synthesized by an effective microwave-assisted deposition method. Theeffect of Pt contents loaded on the Bi2MoO6nanoplates was investigated through the photodegra-dation of rhodamine B (RhB) illuminated by visible radiation. Face-centered cubic (FCC) metallicPt nanoparticles were supported on the surface of orthorhombic Bi2MoO6nanoplates with verygood distribution by a microwave-assisted deposition method. The photocatalytic performance ofBi2MoO6nanoplates was increased with increasing the loaded Pt nanoparticles from 1% to 10%.Upon further increasing the loaded Pt nanoparticles to 15%, the photocatalytic performance forthe degradation of RhB was significantly reduced. In this research, 10% Pt/Bi2MoO6nanocom-posites have the highest photocatalytic activity because Pt nanoparticles are very good electricalconductors that play the role of enhancing photocatalytic reaction rate.

Here, graphene oxide is synthesized and functionalized with methyl viologen and chitosan to be used as a novel catalyst support for Pt nanoparticles. The particle size and distribution of Pt nanoparticles are characterized by transmission electron microscope images. Pt nanoparticles with the mean particle size of 3.62 nm are dispersed on the support very uniformly. The catalytic activity of the prepared catalyst is investigated for methanol oxidation by cyclic voltammetry technique. The prepared catalyst showed very good catalytic activity for methanol oxidation. The experimental and statistical analyses are used to investigate the effect of mutual interaction between temperature and methanol concentration on anodic current density of methanol oxidation. The statistical analysis results reveals that the influence of temperature and methanol concentration as main factors and their reciprocal interactions are significant at α=0.05. Meanwhile, the results confirm that the response increases with both main factors. The enhancement of the anodic current density of methanol oxidation with temperature and methanol concentration is equal to 530.22% and 184.89%, respectively. Therefore, the effect of temperature on the response is higher than that of methanol concentration.

Morphology and size of platinum nanoparticles are a crucial factor in improving their catalytic activity and stability. Here, we firstly report the synthesis of high loading Pt nanoparticles on polydopamine reduced Graphene. The loading concentration of Pt (nanoparticles) NPs on Graphene can be adjusted in the range of 60-70%.With the insertion of polydopamine between Graphene oxide sheets, stacking of Graphene can be effectively prevented, promoting diffusion of oxygen molecules through the Graphene sheets and enhancing the oxygen reduction reaction electrocatalytic activity. Compared to commercial catalysts (i.e., state-of-the-art Pt/C catalyst) the as synthesized Pt supported polydopamine grafted reduced graphite oxide (Pt@PDA-rGO) hybrid displays very high oxygen reduction reaction catalytic activities. We propose a unique 2D profile of the polydopamine-rGO role as a barrier preventing leaching of Pt into the electrolyte. The fabricated electrodes were evaluated with electrochemical techniques for oxygen reduction reaction and the obtained results were further verified by the transmission electron microscopy micrographs on the microstructure of the integrated pt@PDA-rGO structures. It has been revealed that the electrochemical impedance spectroscopy technique can provide more explicit information than polarization curves on the performance dependence on charge-transfer and mass transport processes at different overpotential regions.

Bi2WO6 synthesized by hydrothermal method and heterostructure 1-10wt% Pt/Bi2WO6 nanocomposites synthesized by Sono chemical-assisted deposition method were studied for photocatalysis. The as-synthesized samples were characterized by X-Ray Diffraction (XRD), Fourier Transform InfraRed (FT-IR) spectroscopy, Raman spectrometry, X-ray Photoelectron Spectroscopy (XPS), Transmission Electron Microscopy (TEM) and UV-Visible Diffuse Reflectance Spectroscopy (UV-Vis DRS). The analytical results certified that metallic Pt nanoparticles were loaded on orthorhombic Bi2WO6 thin nanoplates and the visible light absorption of the nanocomposites was improved. The photocatalytic activities of the as-synthesized samples in degrading Rhodamine B (RhB) were investigated under visible light for 180 min. The photodegradation efficiencies were 35.33%, 66.18%, 86.91%, and 94.58% for 0%, 1%, 5%, and 10% Pt/Bi2WO6 samples, respectively. The 10% Pt/Bi2WO6 nanocomposites have the highest photocatalytic activity because the Pt nanoparticles have the highest activity in harvesting visible light and the strongest Surface Plasmon Resonance (SPR) effect. A possible mechanism for photocatalysis, main active radicals of the photodegradation process, and recyclability of the heterostructure Pt/Bi2WO6 nanocomposites were also investigated in this research.

In this study, titanium dioxide (TiO2) containing 1 wt% of various elements (Ag, Cr, Cu, V, or Pt) was synthesized by a one-pot sol-gel method. The produced materials were extensively characterized by means of X-ray diffraction (XRD), BET surface-area measurements, Raman spectroscopy, UV-Vis spectroscopy and Transmission electron microscopy (TEM). UV-Vis spectroscopy demonstrated a clear shift in the absorbance of modified TiO2 towards the visible light region. The photocatalytic performance of the prepared materials was evaluated in the photooxidation of methylcyclohexane (MCH) under the illumiation of UV or Visible light. The performance was monitored by in situ ATR-FTIR. The best catalytic performance was obtained when Cr/TiO2 was applied. The photocatalytic activity under visible light illumination could be further enhanced by photodeposition of Pt nanoparticles (0.06 wt % Pt) on the surface of Cr/TiO2. The origin of the synergetic effect of Cr6+ and Pt nanoparticles will be discussed.

In this study, multiwall carbon nanotubes (MWCNTs) were chemically oxidized (OMWCNTs) and functionalized with ethylenediamine (EDAMWCNTs) and diethylenetriamine (DETAMWCNTs) as amine precursors. The electrocatalysts were prepared through deposition of Pt nanoparticles on the functionalized MWCNTs by polyol method. The average size of Pt nanoparticles was found to lie between 4 and 5 nm. Cyclic Voltammetry (CV), Rotating Disk Electrode (RDE), Electrochemical Impedance Spectroscopy (EIS), and Chronoamperometry (CA) were employed to evaluate the electrochemical properties of the electrocatalysts. The Electrochemical active surface area (EASA), number of electron transferred (n), and onset potential for EDAMWCNTs and DETAMWCNTs were found to be about 32.2 and 45.8 (m2/g Pt), 4.03 and 4.10 (electron per oxygen molecule), and 0.986 and 0.997 (V vs RHE), respectively. However, in the case of Pt-OMWCNTs the above mentioned electrochemical characteristics were calculated to be 24.2 (m2/g Pt), 3.34 (electron per oxygen molecule), and 0.824 (V vs RHE), respectively. Moreover, EIS and CA indicate that introducing amine functional groups lead to less electron transfer resistance and better electrocatalytic activity and stability during oxygen reduction. The results show that the higher number of nitrogen atoms within the amine functional groups the more enhanced electrocatalytic performance of Pt nanoparticles in ORR.

In this study, graphene oxide was prepared by a modified Hummers’ method and used as support for dispersing of nanoparticles. SrCoO3-δ nanoparticles were prepared and characterized by X-ray diffraction technique. They were used accompanied by Pt nanoparticles on the reduced graphene oxide (RGO) support for preparing of Pt-SrCoO3-δ-RGO catalyst. Transmission electron microscopy images were used to show the morphology and distribution of nanoparticles. The catalytic activity of the prepared catalyst was investigated for methanol electrooxidation by cyclic voltammetry and electrochemical impedance spectroscopy techniques and compared with the catalytic activity of Pt-RGO catalyst. The effects of some experimental parameters affecting on methanol oxidation such as methanol concentration, temperature and scan rate were investigated on Pt-SrCoO3-δ-RGO catalyst and the optimum conditions were suggested. Pt-SrCoO3-δ-RGO catalyst showed better catalytic activity for methanol oxidation compared with Pt-RGO catalyst indicating that Pt-SrCoO3-δ-RGO can be used as a promising catalyst for application in direct methanol fuel cells.

In the present work, the electrooxidation of formic acid and formaldehyde; potentially important fuels for future fuel cells, was investigated on the Fe3O4@Pt core-shell nanoparticles/carbon-ceramic electrode (Fe3O4@Pt/CCE). The Fe3O4@Pt nanoparticles were prepared via a simple and fast chemical method and their surface morphology, nanostructure properties, chemical composition, crystal phase, and electrochemical behavior were investigated by scanning electron microscope, transmission electron microscope, X-ray diffraction, energy dispersive X-ray spectroscopy and electrochemical methods, respectively. Then the electrocatalytic activity of the Fe3O4@Pt/CCE toward the oxidation of formic acid and formaldehyde was studied in details. The primary electrochemical analysis shows that the Fe3O4@Pt/CCE has superior catalytic activity and stability for formic acid and formaldehyde oxidation compared to Pt-alone nanoparticles on the carbon-ceramic electrode (Pt/CCE). The present investigation demonstrates that the Fe3O4@Pt/CCE electrocatalyst may play a significant role in future fuel cell applications.