Platinum Nano Research Articles

Deriving electricity from dye processing wastewater using single chamber microbial fuel cell with carbon brush anode and platinum nano coated air cathode.

Single chamber air cathode microbial fuel cell (MFC) is a promising and sustainable technology to generate electricity. In the present study, the potential of air cathode MFC treating dye processing wastewater was investigated at various organic loads with interest focused on power densities, organic removal and coulombic efficiencies. The highest power density of about 515mW/m2 (6.03W/m3) with 56% of coulombic efficiency was procured at 1.0 (g COD/L) organic load. The high potency of TCOD (total chemical oxygen demand), SCOD (soluble chemical oxygen demand) and TSS (Total Suspended Solids) removal of about 85%, 73% and 68% respectively was achieved at the organic load of 1.0 (g COD/L). The bacterial strains in anode region at the initial stage of MFC operation were reported to be responsible for potential organic removal. The bacterial strains in air cathode MFC were identified as Paenibacillus sp. strain JRA1 (MH27077), Pseudomonas sp. strain JRA2 (MH27078), Ochrobactrum sp. strain JRA3 (MH27079), Sphingobacterium sp. strain JRA4 (MH27080), Stenotrophomonas sp. strain JRA5 (MH27081), Bacillus sp. strain JRA6 (MH27082) and Clostridium sp. strain JRA7 (MH27083) using phylogenetic analysis. After 60days of air cathode MFC operation, the bacterial community in biofilm samples was dominated by Bacillus, Ochrobactrum and Pseudomonas (20-22%). The biofilm sample collected from the carbon brush consisted of Bacillus (33%), Ochrobactrum (30%), Pseudomonas (28%), Clostridium (6%) and Stenotrophomonas (3%). The present study revealed the treatment efficiency of dye processing wastewater along with power generation in single chambered air cathode MFC.

Inhibition of TRPV1 Channel Activity in Human CD4⁺ T Cells by Nanodiamond and Nanoplatinum Liquid, DPV576.

Background: Transient receptor potential vanilloid (TRPV) channels act as sensors of pain, temperature, and other external stimuli. We have recently shown that DPV576, an aqueous mixture of nanodiamond (ND) and nanoplatinum (NP), can modulate the activity of TRPV on human primary keratinocytes, suggesting their potential as a possible pain modulator. Here, we sought to examine the effect of DPV576 in modulating the functions of human CD4+ T lymphocytes and whether the modulation is mediated via TRPV channels. Materials and methods: Human primary CD4+ T cells were activated with anti CD3/CD28 with and without DPV576 at 1:10 and 1:100 dilutions for 24 h in vitro. TRPV receptor expression (TRPV1 and TRPV4) on CD4+ T cells were examined by flow cytometry. The capacity of DPV576 to modulate the activity of TRPV1 agonist capsaicin in CD4+ T cells was also determined. Activation of CD4+ T cells was determined by production of cytokines TNF-α, IFN-γ, and IL-10 using specific ELISA kits. Results: DPV576 treatment of CD4+ T cells that were activated with anti CD3/CD28 resulted in decreased expression of the TRPV1 channel, but had no effect on TRPV4. This was accompanied by decreased secretion of IFN-γ and reduced expression of TRPV1 in capsaicin activated CD4+ T cells. In addition, DPV576 inhibited the capsaicin, induced the production of IFN-γ, and enhanced the secretion of IL-10. Conclusion: We conclude that short term exposure to DPV576 inhibits the activity of TRPV1 channels in CD4+ T lymphocytes, which may suggest its possible beneficial use for pain management.

Tungsten carbide/carbon composites coated with little platinum nano particles derived from the redox reaction between in-situ synthesized WC1−x and chloroplatinic acid as the electrocatalyst for hydrogen evolution reaction

A kind of less platinum hydrogen evolution reaction (HER) catalyst, 3%Pt/WC/C10, is successfully synthesized using a simple in-situ platinum reduction method of directly mixing WC/C10 and chloroplatinic acid in deionized water and then drying. The structure and morphology are mainly characterized by X-ray diffraction (XRD), high resolution transmission electron microscopy (HRTEM) and X-ray photoelectron spectroscopy (XPS). The as-synthesized 3%Pt/WC/C10 catalyst behaves the most excellent synthetically electrocatalytic performance with a small overpotential of 85 mV at 10 mA cm−2 and 129 mV at 30 mA cm−2. It is almost same with that commercial 10%Pt/C catalyst, which indicates that the synergistic role of tungsten carbide and platinum can effectively reduce the amount of platinum on the condition of obtaining equivalent electrocatalytic activity. The stability after 1000 cycles is observed more excellent than original sample at the current density above 40 mA cm−2. The reason of excellent electrocatalytic stability maybe the turning of from residual platinum hydroxide including Pt(IV) has been reduced by hydrogen adsorption on electrode surface to Pt(0) and increase the ability of corrosion resistance.

Nano Pt@ZIF8 Modified Electrode and Its Application to Detect Sarcosine

Sarcosine is a newly discovered effective biomarker for prostate cancer. However, the low concentration of sarcosine in tissue cells, plasma or urine blocks the development of sarcosine biosensors. In this manuscript, porous zeolitic imidazolate framework-8 (ZIF8) was synthesized and was used as carriers to load nano platinum (Pt@ZIF8). The porous structure of ZIF8 helped to stabilize the nano platinum and keep its high catalytic activity. The Pt@ZIF8 modified sarcosine biosensor had good response toward sarcosine due to its unique structure and morphology. The linear range of the as prepared biosensor is from 5 to 30 μM, which is consistent with the detection demand. The prepared sarcosine biosensor is suitable to be developed as a kind of portable diagnostic facilities for prostate cancer.

Highly-Sensitive Non-Enzymatic Glucose Sensor via Nano Platinum Crystals Fabricated by Phase-Controlled Electrochemical Deposition

In this study, non-enzymatic glucose sensors were designed and fabricated by electrochemical deposited platinum nano-crystals, including Platinum nanosphere (Pt NS), Platinum nanorose (Pt NR), and Platinum nanocubes (Pt NC) on fluorine-doped tin oxide glass. The control of the morphologies and growth types was conducted by either potentiostatic or pulse-mode potentiostatic deposition for synthesizing Pt NS, Pt NR, or Pt NC, respectively, at room temperature. Among three Pt nano-crystals, The Pt NC displayed the highest electrocatalytic activity to oxidation of glucose (glucolactone) owning to the single crystalline structure. The developed Pt NC sensor showed a fast response time (2 s), a high sensitivity of 20.75 μA/mM⋅cm, and a detection limit of 0.7 μM (at S/N ratio = 3). By setting glucose oxidation potential to 0.1 V, the Pt NC electrode provided a linear dependence (R2 = 0.99086) to glucose in a concentration range from 0.33 to 12.50 mM. The Pt NC electrodes showed stable, highly sensitive, low working oxidation potential, low loading of Pt, and rapid amperometric response in sensing glucose with excellent reproducibility and selectivity, possessing a great potential for non-enzymatic glucose sensing applications.

Electrochemical Biosensor Based on Nano TiO2 Loaded with Highly Dispersed Photoreduced Nano Platinum

Precious metal nanomaterials have been widely used in electrochemical sensors. Further improving the dispersion of nanomaterials is beneficial to improving sensor performance and reducing the usage of noble metals. In this work, platinum nanoparticles (NPs) were loaded onto titanium dioxide nanoparticles (TiO2) by the photoreduction method. The morphology, content, and distribution of NPs were determined by high resolution transmission electron microscopy (HRTEM) and energy dispersive spectroscopy (EDS). The method has simple steps and a short synthesis time (14 min). NPs with an average particle size of about 5 nm were uniformly dispersed on the surface of TiO2 nanoparticles. The nano Pt loaded TiO2 (Pt/TiO2) nanocomposites were modified on the surface of the glassy carbon electrode, and an enzyme-free H2O2 sensor was constructed and used as a carrier of lactate oxidase to prepare an amperometric lactic acid biosensor. The enzyme-free H2O2 sensor has a wide detection range (0.002–15 mM), a low detection limit (0.92 μM), and has a rapid response time (2 s) toward H2O2 with a relative standard deviation (RSD) of less than 3%. At the same time, the constructed lactic acid biosensor has a linear detection range of 0.003–0.7 mM and a detection limit of 3 μM toward lactate.

New pyrimidine based ligand capped gold and platinum nano particles: Synthesis, characterization, antimicrobial, antioxidant, DNA interaction and in vitro anticancer activities

In this research work, we have synthesized new pyrimidine based Schiff base ligand, 2-((4,6-dimethoxypyrimidine-2-yl)methyleneenamino)-6-methoxyphenol (DPMM) capped gold (Au) and platinum (Pt) nanoparticles (NPs) by modified Brust-Schiffrin method. The characteristics of DPMM-Au NPs and DPMM-Pt NPs have been examined by UV–Visible, FTIR, SEM, TEM and powder XRD analysis. SEM analysis result shows that surface morphology of the DPMM-Au NPs and DPMM-Pt NPs are in granular and spherical shape, correspondingly. The size of the DPMM-Au NPs and DPMM-Pt NPs are approximately 38.14±4.5 and 58.64±3.0nm respectively, which confirmed by TEM analysis. The DPMM-Au NPs and DPMM-Pt NPs have potent antimicrobial against Escherichia coli, Klebsiella pneumonia, Pseudomonas fluorescens, Shigella sonnei, Staphylococcus aureus and Aspergillus niger, Candida albicans, Candida tropicalis, Mucor indicus, Rhizopus strains. The DPMM-Au NPs and DPMM-Pt NPs have good antioxidant activities than the free ligand (DPMM). The spectroscopic and viscometric measurement confirms the hydrophobic DNA binding abilities of the newly prepared DPMM capped metal NPs. Moreover, the in vitro anticancer activity of DPMM, DPMM-Au NPs and DPMM-Pt NPs against cancer (MCF-7, HeLa & HEp2) and normal (NHDF) cell lines have performed using MTT assay. These results reveals that, DPMM-Au NPs and DPMM-Pt NPs having significant cytotoxic activity against the cancer cell lines and least toxic effect on normal cell line as compared to standard drug cisplatin.

A novel chondroitin sulfate decorated nano platinum for the treatment of osteoarthritis

The present work showed the biofabrication of platinum nanoparticles (PtNPs) using chondroitin sulfate via a facile, eco-friendly route by just heating leaf extract and H2PtCl6·6H2O (Chloroplatinic acid) solution which gave a brown-colored PtNPs dispersion. The assynthesized PtNPs were analyzed by using Transmission electron microscopy (TEM), Energy dispersive spectroscopy (EDX), X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy and Selected area electron diffraction (SAED). TEM analysis showed PtNPs of irregular shape with a size existed in the range from 3 to 5nm. From zeta potential studies it is found the surface charge of the synthesized PtNPs is negative (−25.6mV). FTIR analysis and zeta potential measurements of PtNPs confirm the capping of chondroitin sulfate onto the surface of nanoparticles. XRD and SAED pattern revealed the crystalline nature of synthesized nanoparticles. Further, the in-vitro cytotoxicity of PtNPs against the osteoarthritis chondrocytes showed their biocompatibility, hence the obtained nanoparticles may have future scope in the treatment of osteoarthritis. Also, the present approach is green alternative to the traditionally available chemical methods that are currently been used now a days using chemical reagents such that are hazardous to human and environment.

Synthesis and characterization of platinum nano sized particles by laser ablation in C2H6O2 solution

Platinum nano sized particles (Pt NPs) are superior catalysts for many intentions, such as glucose sensors, cancer therapy, gas sensors, etc. Here, Pt NPs were produced by pulsed laser ablation in C2H6O2 solution using Q-switched Nd:YAG laser, for the first time. Then, the influence of the laser fluence during synthesis of them was investigated; and they were characterized by UV–vis spectroscopy, TEM, FE-SEM, XRD, FT-IR, and Raman spectroscopy. The results showed that with increasing laser fluence, the mean particle size of the spherical NPs enhanced. Meanwhile, they had a polycrystalline cubic structure. Correspondingly, the plasmon peak position of generated NPs in the absorption spectra shifted from 257 to 266 nm, with a rise of laser fluence. The IR and Raman spectroscopy was used to achieve the information about the surface state of Pt NPs. We propose that the optimum adjusted laser fluence is an important factor to increase the ablation efficiency.

Effect of Nanodiamond and Nanoplatinum Liquid, DPV576, on Human Primary Keratinocytes.

Nanofabrics are now being used in a wide range of products that come into direct contact with skin, including carpet, clothing, and medical fabrics. In the current study, we examined the effect of a dispersed aqueous mixture of nanodiamond (ND) and nanoplatinum (NP) (DPV576) on human primary keratinocytes with respect to transient receptor potential vanilloid (TRPV) channel expression, secretion of cytokines and production of nerve growth factor (NGF). Keratinocytes were treated with DPV576 at concentrations of 1:10 and 1:100 dilutions for 24 hours in vitro, and their activation of was determined by production of cytokines TNF-α, IL-1β, and prostaglandin (PGE2), and by production of NGF. Inhibitor experiments were carried out by incubating keratinocytes with the TRPV4-selective antagonist HC-067047. TRPV receptor expression (TRPV1, TRPV3 and TRPV4) on keratinocytes as well as changes in Ca2+ potential were examined by flow cytometry. DPV576 treatment of keratinocytes resulted in the following effects: (1) stimulation of keratinocytes as indicated by the significant secretion of cytokines IL-1β, TNF-α, and PGE2, an effect noted only at higher concentration (1:10); (2) significant decrease in the expression of TRPV4 on keratinocytes with a spike in the calcium flux, but no change in the expression of TRPV1 and TRPV3; (3) induction of cytokine secretion independent of TRPV4, as the addition of TRPV4 inhibitor had no significant effect on the cytokine production from keratinocytes; (4) induction of NGF secretion by keratinocytes. These results demonstrate that DPV576 activates keratinocytes via multiple signaling pathways which may reduce stress associated with inflammation, pain, and circadian rhythms. ND/NP-coated fabrics that target the modulation of local inflammation, pain, and circadian rhythms could potentially be of benefit to humans.

Electrochemical Synthesis and Reduction of Aniline-Tetramer: Application Prospect as MOR Electrocatalyst

The emeraldine-base form of aniline-tetramer (TAni-EB) is synthesized from N-phenyl-p-phenylenediamine by electrochemical (Potentio static and Galvano static) methods. Chemically synthesized TAni-EB is reduced electrochemically for the first time in literature to its lower (Lueco-emeraldine, LEB) oxidation state. The obtained TAni-EB and TAni-LEB were characterized by FT-IR, 1H NMR, UV-Vis, conductivity (four probes) and cyclic voltammetry. Cyclic voltammograms of chemically synthesized and electrochemically synthesized TAni showed identical redox peaks. The aniline-tetramer (EB) is first time used as support for platinum Nano particles (Pt/TAni) for methanol electro-oxidation. The Pt nanocomposites are characterized using XRD, FE-SEM, EDAX and XPS analyses. Carbon-CS-TAni, Carbon-PS-TAni and Carbon-GS-TAni supported platinum (Pt/C-CS-TAni, Pt/C-PS-TAni and Pt/C-GS-TAni) nanocomposites are also synthesized and their MOR catalysis is compared. The Pt/C-CS-TAni nanocomposite show better electrocatalytic than Pt/C-PS-TAni, Pt/C-GS-TAni and Pt/CS-TAni toward methanol oxidation.

Sacrificial Reducing Agent Free Photo-Generation of Platinum Nano Particle over Carbon/TiO2 for Highly Efficient Oxygen Reduction Reaction.

Electrocatalytic materials for oxygen reduction reaction, currently dominated by platinum/carbon catalyst is marred by drawbacks such as use of copious amount of Pt and use of “non-green” sacrificial reducing agent (SRA) during its synthesis. A single stroke remedy for these two problems has been achieved through an in-situ aqueous photoreduction void of even trace amounts of SRA with an enhanced activity. Reduction of PtCl62− salt to Pt nano particles on carbon substrate was achieved solely using solar spectrum as the source of energy and TiO2 as photocatalyst. Here, we demonstrate that this new procedure of photoreduction, decorates Pt over different types of conducting allotropes with the distribution and the particle size primarily depending on the conductivity of the allotrope. The Pt/C/TiO2 composite unveiled an ORR activity on par to the most efficient Pt based electrocatalyst prepared through the conventional sacrificial reducing agent aided preparation methods.

Photocatalytically Generated Pt/C-TiO2 Composite As ORR Catalyst

Metal decorated carbon materials have grabbed the attention of the world due to its tremendous application in various paths of life. Among the various metals decorated over carbon, transition metals like Pt is more talked about when it comes to catalytic reactions in energy devices. Very recently we reported exfoliated acetylene black/Pt nano-particles showing extraordinarily high ORR activity [1]. However, the general methods used for decoration of metal nanoparticles on to carbon substrates are basically carried out by employing sacrificial reducing agents (SRA) like alcohols or other reducing agents at elevated temperatures, which are against to the green approach. Lookout for alternative green procedures has recently ended up in looking into exploiting photo-reduction processes. However, research dealing with the photo-reduction of metal salts to metals in aqueous medium without a SRA is not fully studied [2]. Alongside ‘green’ aspect, large scale commercial applications are precluded by the high manufacturing cost of the ORR catalyst. Hence, researcher have been focusing on reducing the cost of the catalyst by decreasing the amount of Pt used with the introduction of transition metal oxides and doping of nitrogen in carbon. The present work deals with the photo-reduction of chloroplatinic acid on to graphite and graphene using TiO2as photo-catalyst irradiated by solar simulator. Graphite (carbon substrate) weighing 90mg was ultrasonicated in water for 2 hrs to obtain a uniform dispersion. To this uniform dispersion, 10 mg of TiO2and 800 μL of 0.045 M chloroplatinic acid solution was added and ultrasonicated for 15 min. The solution was irradiated using solar simulator for 5 hrs. The reaction completion time was confirmed by studying the open-circuit potential of the solution across Pt wire working electrode and Ag/AgCl reference electrode. The material was then subjected to morphological characterization by TEM and elemental analysis by XPS. Further, the material was studied for its ORR behavior using cyclic voltammetry. TEM micrographs showed uniform distribution of Pt-nps all over the graphite along with TiO2. Platinum nano particles were in the range of 5 to 10 nm in size Fig1 (A and B). Elemental characterization by XPS (Fig 1C) revealed the presence of Pt, O, Ti and C along with trace amounts of chlorine given in Fig. 1D. The reaction completion time was studied using change in the open circuit potential (OCP), which was found to be nearly 4 hrs (Fig. 1E). Oxygen reduction characteristics of the electrocatalyst was studied using cyclic voltammetry. The voltammograms (Fig 1F) confirmed that the prepared material to be a promising catalytic material. The electrochemical active surface area (ECSA) was calculated as 62.24 m2/gm. The ECSA was observed to be significantly high compared to commercial Pt/C catalyst. In conclusion, a highly reproducible, environmentally benign and ultrafast method was developed for the preparation of active ORR catalyst (for use in Fuel cell and Lithium-air battery). The method uses solar light as the only source of energy in the preparation of this catalytically efficient composite utilizing abundant and environmentally benign TiO2 as photo-catalyst. Using this green methodology, preparation of novel composites containing TiO2 particles, graphite substrates and platinum nanoparticles was successfully carried out. As prepared material showed excellent ORR activity comparable to the best of commercial ORR catalysts. It can also be confirmed that this method is feasible for all the conducting carbon substrates. The above results clearly demonstrates that the novel, green and a very viable method of Pt decoration method is as efficient as rather more efficient as that of well-established methods using SRA. References 1) R. Badam, R. Vedarajan, N. Matsumi, Chem. Commun., 2015, 51, 9841. 2) F. Mahlamvana, R.J. Kriek, Appl. Cat. B, 2014, 148-149, 387. Figure 1

Performance and Durability of Pt-Ti Catalyst for Oxygen Electroreduction

Fuel cells are expected to be a key next-generation energy source used for vehicles and homes, offering high energy conversion efficiency and minimal pollutant emissions. The high efficiency arises from the fact that fuel cells convert chemical energy directly into electrical energy without the Carnot limitation of thermal engines. However, due to the extreme operating environment, Pt was almost exclusively the only practical catalyst for molecular oxygen electroreduction in PEM fuel cells. Recently, considerable efforts have been made to investigate synergy effects of platinum alloyed with base metals to improve the sluggish kinetics of oxygen reduction reaction of Pt catalyst. The more active Pt-alloy catalysts, in return, may arise the durability issue under the extreme environment of PEM fuel cell operation. In this presentation, results of a more active yet durable PtTi alloy catalyst will be discussed for oxygen reduction reaction in acidic media, including (i) combinatorial high-throughput discovery of PtTi alloy composition; (ii) synthesis and characterization of nano-scale PtTi particles with controllable size, phase, and individual particle composition; and (iii) electrochemical STM and ICP characterization of coarsening and corrosion of PtTi alloy catalyst in comparison with Pt and PtCo catalysts. A novel combinatorial high-throughput electrocatalyst discovery workflow and associated tools were developed [1-4], where thin films of alloys can be made through a Multi-sources Physical Vapor Deposition system [5], and the resulted materials can be electrochemically screened by a Multi-channel Rotating Disk Electrode system [6]. PtTi binary system has been screened using this methodology for activity-stability-composition relationship and the best alloy composition was identified. In addition to the discovery of alloy compositions, engineering the PtTi alloy particles in nanoscale has been a challenge. Several synthesis technologies were studied and developed to achieve capabilities of controlling particle size and particle microcomposition [7]. The results show that by careful engineering the particle size and microcomposition in nanoscale, it is able to achieve the superior electrocatalytic activity predicted by the combinatorial high-throughput discovery. Electrochemical STM technique, in combination with electrochemical potentiostating, potential cycling, and ICP analysis, was used to monitor the coarsening and base metal corrosion under dynamic fuel cell operation conditions and compared with phenomena observed from Pt and PtCo catalysts [8-10]. The results show that PtTi not only is more active than Pt and much stable than PtCo, but also can mitigate the catalyst coarsening. Reference [1] T. He and E. Kreidler, Phys. Chem. Chem. Phys. 10, 3731 (2008). “Combinatorial screening of PtTiMe ternary alloys for oxygen electroreduction”. [2] E. Kreidler and T. He, in Catalysts for Oxygen Electroreduction – Recent Developments and New Directions (Ed. T. He, Transworld Research Network) Chapter 4, p.63 (2009). “Oxygen reduction on Pt alloys: high throughput combinatorial screening of Pt binary alloys”. [3] T. He, E. Kreidler, L. Xiong and E. Ding, J. Power Sources 165, 87 (2007). “Combinatorial screening and nano-synthesis of platinum binary alloys for oxygen electroreduction”. [4] T. He, E. Kreidler, L. Xiong, J. Luo and C.J. Zhong, J. Electrochem. Soc. 153, A1637 (2006). “Alloy electrocatalysts: combinatorial discovery and nano-synthesis”. [5] T. He, E.R. Kreidler and T. Nomura, US 8,944,002 (2015). “High throughput physical vapor deposition system for material combinatorial studies”. [6] T. He, US 7,077,946 (2006). “High throughput multi-channel rotating disk or ring-disk electrode assembly and method”. [7] E. Ding, K.L. More and T. He, J. Power Sources 175, 794 (2008). "Preparation and characterization of carbon-supported PtTi alloy electrocatalysts". [8] L. Tang, B. Han, K. Persson, C. Friesen, T. He, K. Sieradzki and G. Ceder, J. Am. Chem. Soc. 132, 596 (2010). “Electrochemical stability of nanometer-scale Pt particles in acidic environments”. [9] Q. Xu, E. Kreidler, D.O. Wipf and T. He, J. Electrochem. Soc. 155, B228 (2008). "An in-situ electrochemical STM study of potential-induced coarsening and corrosion of platinum nano crystals". [10] Q. Xu, T. He and D. Wipf, Langmuir 32, 9098 (2007). "An in-situ electrochemical STM study of the coarsening of platinum islands at double-layer potentials".

Influence of the Graphitisation Degree of Carbon Nano Fibres Serving as Support Material for Noble Metal Electro Catalysts on the Performance of PEM Fuel Cells

In this experimental work polymer electrolyte membrane fuel cell (PEMFC) electrodes are analysed, which are prepared by the use of two sorts of carbon nano fibres (CNF) serving as support material for platinum nano particles. Those CNFs, which are heat treated subsequently to their production, have a higher graphitisation degree than fibres as produced. The improved graphitisation degree leads to higher electrical conductivity, which is favourably for the use in PEMFC electrodes. Samples have been analysed, in order to determine graphitisation degree, electrical conductivity, as well as morphology and loading of the prepared electro catalyst. Membrane electrode assemblies manufactured from prepared electrodes are analysed in-situ in a PEM fuel cell test environment. It has been determined that power output for samples containing CNFs with higher graphitisation degree is increased by about 13.5 %.

Trace Determination of Acesulfame-K Using Voltammetric Nanosensor and Evaluation of Kinetic Parameters

Because of widespread application in food industry, measurement of Acesulfame-K (AcK) is an important subject. This material is a synthetic and non-caloric sweetener that has been widely used instead of sugar in foodstuffs. Powerful analytical methods are needed for this growing market to assure quality control and the ingredients of the products. Till now, several analytical methods have been reported concerning the determination of AcK and other sweeteners including linear sweep voltammetry, solid-phase extraction and liquid chromatography–tandem mass spectrometry, liquid extraction and liquid chromatography-tandem mass spectrometry, square-wave voltammetry, differential pulse voltammetry, capillary electrophoresis, FT-Raman spectroscopy, Spectrophotometry, sinusoidal envelope voltammetry and potentiometry [1-5]. Consequently, the determination of AcK is regarded as an interesting issue for many researchers that work in the spectroscopic, chromatographic and electroanalytical methods of analytical chemistry. Electroanalytical literature survey shows not only the lack of mechanistic and kinetic information about AcK electrochemical behavior, but also absence of ultrasensitive AcK nanosensor. Thus, construction of nanoparticle-based AcK voltammetric sensor and evaluation of kinetic parameters of AcK can be considered as the novel aspects of this research that might differentiate this one from the previously reported ones, to the best of our knowledge. The cyclic voltammetric (CV), differential pulse voltammetric (DPV) and electrochemical impedance spectroscopic (EIS) measurements were performed with µAutolab FRA2 Potentiostat-Galvanostat. A three-electrode system was used with the Pt rod (2 mm/ 87 mm) or NPtAPE as working electrodes, glassy carbon electrode (GC rod 2mm/ 76mm) as the counter and an Ag/AgCl as the reference electrode (Autolab comp.). All tests were conducted under room temperature. A digital pH meter (Jenway 370) was applied for pH adjustment. The AcK voltammetric nanosensor (NPtAPE) was constructed by using nano Platinum (NPt) and Agar paste (AP) as electrocatalyst and inert support material, respectively. The NPt content of NPtAPE is an important factor that affects the obtained current intensity of this nanosensor. Using Nyquist manner plots, the EIS confirmed diminishing of charge transfer resistance (Rct) and enhancing electron transfer at the surface of NPtAPE. Various supporting electrolytes such as KCl, NaNO3 and KNO3 were tested to select the best of them in forthcoming experiments. Exact experimental calculations revealed the best pH and kinetic parameters of electrooxidation of AcK at the working electrode surface. After that, probable mechanism for this process was suggested which has three steps. NPtAPE showed linear dynamic ranges and extraordinary pM detection limit that made it a powerful device in sensing of AcK at trace level. In the final step of the work, NPtAPE was utilized for AcK quantitation in candy samples purchased from different companies successfully. In summary, NPtAPE is a new voltammetric nanosensor for ultrasensitive and rapid AcK determination in candy samples. Hence, it can be recommended for the routine quality control of AcK in food products. The proposed method was based on the oxidation of AcK by appropriate potential at the NPtAPE surface. The principal advantages of the proposed nanosensor are its excellent detection limit, wide linear dynamic ranges, simplicity, selectivity and rapidity. The heterogeneous rate constant confirms the catalytic role of NPt particles in enhancing S/N ratio in order to constructing ultrasensitive nanosensor. Keywords: Acesulfame-K; Nano Platinum; Cyclic voltammetry; Differential pulse voltammetry; Kinetic parameters

Nano carbon supported platinum catalyst interaction behavior with perfluorosulfonic acid ionomer and their interface structures

The interaction between perfluorosulfonic acid ionomer and supported platinum catalyst is essential. It directly influences platinum accessibility, stability of carbon support and platinum, proton conductivity and electron conductivity in an electrode. In this study, we compare the adsorption behavior of Nafion ionomer on platinized carbon nano fibers (CNFs), carbon nano tubes (CNTs) and amorphous carbon (Vulcan). The interaction is affected by the catalyst surface oxygen groups as well as porosity. Comparisons between the carbon supports and platinized equivalents are carried out. It reveals that the platinization step modifies the surface nature of the carbon supports in terms of specific surface area, crystallinity and especially porosity; therefore, ionomer adsorption over carbon is not always representative for the ionomer adsorption over carbon supported catalyst, though indicative. Moreover, the ionomer may have an adsorption preference to the platinum nano particle rather than to the overall catalyst. This was verified by a close examination on the decomposition temperature of the carbon support and the ionomer. The electrochemical stability of the catalyst ionomer composite electrode suggests that the ionomer adsorption on the overall catalyst is a more stable interface structure for fuel cell application.

Flow Aerobic Oxidation of Alcohols Using a Supported Nano Platinum Catalyst

Flow Aerobic Oxidation of Alcohols Using a Supported Nano Platinum Catalyst

Nano Platinum Decorated Graphene Wrapped a-MnO2 Nanocomposite Lithium Air Breathing Cathode for Li-O2 Batteries

Currently, battery research and development have focused on energy storage and conversion with high energy, high power density, and reliable safety. Among batteries, the lithium air battery has recently captured worldwide attention due to its ultrahigh specific energy density of 11.140 Whkg-1 rivaling that of gasoline (1, 2). However, Li+ reduces molecular O2 to form insoluble lithium peroxide (Li2O2) or lithium oxide (Li2O) at the cathode during discharge, which gradually blocks the electrolyte and oxygen pathways and eventually also limits the rate capability, capacity, and cyclic life of Li-O2batteries. Therefore, the two properties of the cathode materials are the important features. The first one is the porosity of the air electrode and the second one is the oxygen reduction (ORR) and oxygen evolution reaction (OER) behaviors of the cathode (2, 3). In this study, nano platinum decorated Graphene wrapped a-MnO2 nanocomposite cathode was produced to increase cycle life and the capacity of the Li-O2 batteries. Before production of the composite cathodes, Graphene Oxide (GO) was synthesized by Hummers Method and a-MnO2 nanowires was synthesized using microwave hydrothermal synthesis method. To production of the composite cathodes, GO and a-MnO2 dispersed in the distilled water and homogenously mixed using ultrasonication for 1 h. After then H2PtCl6 was added in the suspension under stirring. After then, NaBH4 solution was slowly added in the suspension to reduce H2PtCl6 and GO into platinum and Graphene, respectively. After centrifugation and drying of the products, Graphene/a-MnO2/Pt nanocomposite was obtained. Using this composite, Graphene/a-MnO2/Pt nanocomposite cathode was prepared. To prepare Graphene/a-MnO2/Pt nanocomposite cathode, 15wt.% PVDF dissolved in NMP solution and 85 wt.% Graphene/a-MnO2/Pt nanocomposite were mixed and obtained slurry cast on the nickel foam. After drying of the samples in vacuum oven, Graphene/a-MnO2/Pt nanocomposite cathode was obtained. The structure of the composite was characterized using X-ray diffraction pattern, Raman spectroscopy, scanning electron microscopy and transmission electron microscopy. Electrochemical characterization of the Graphene/a-MnO2/Pt nanocomposite cathode was performed between 2.15 V and 4.25 V at a constant current density of 0.1 mAcm-2 in ECC-Air test cell (purchased from EL-Cell Company in Germany). In order to investigate electrochemical reaction of the cathode with electrolyte, cyclic voltammetry test was carried out at a scan rate of 0.1 mV s-1. For further electrochemical characterization, electrochemical impedance spectroscopy of the cathode was investigated after selected cycles in the frequency range of 1000 kHz to 0.1 Hz with AC amplitude of 10 mV.

Development and performance evaluation of nano platinum coated titanium electrode for application in nitric acid medium

Nano platinum coated titanium (NPCT) electrodes were developed using electrodeposition assisted hydrothermal method for application as electrodes in reprocessing plant under severe corrosive environment. After synthesis, the morphology of the NPCT electrode surface was characterized using Field emission scanning electron microscopy (FESEM). The phase and chemical state of the modified electrode was investigated using X-ray diffractometer (XRD) and X-ray photoelectron spectroscopy (XPS) respectively. The enhanced electrochemical activity of NPCT electrode was established by conducting hydrogen adsorption-desorption study and electrochemical oxygen reduction studies. The performance of the electrode was investigated by employing it as anode in cerium oxidation under an applied current of 0.1 A in 11.5 M nitric acid. Post performance analysis reveals the stability of the synthesized electrode.