Properties Of Pt Nanoparticles Research Articles

High-performance Pt/Ti3C2Tx MXene based graphene electrochemical transistor for selective detection of dopamine

Accurate measurement of dopamine (DA) is of great significance for human health monitoring and disease prevention. Herein, two-dimensional Ti3C2Tx MXene with high performance was prepared by layer liquid exfoliation method and used for the modification of gate electrode. The glassy carbon electrode (GCE) modified with Pt/Ti3C2Tx was used as the gate, and assembled with monolayer graphene channel to form a complete transistor device. The device combines the amplification effect of transistors, good electrical conductivity of Ti3C2Tx MXene and excellent catalytic properties of Pt nanoparticles, showing a low detection limit (50 nM) and a wide detection concentration range (50 nM-9 mM) of DA. Ti3C2Tx MXene not only provides a large number of attachment sites for the deposition of Pt nanoparticles, but also improves the electrical conductivity and hydrophilicity of the electrode material, thus enhancing the sensitivity of the device and facilitating the penetration of the solution to be measured. In addition, Ti3C2Tx MXene is negatively charged, it has a certain electrostatic adsorption effect on protonated DA and electrostatic repulsion effect on negatively charged interfering substances. As a result, the device exhibits good selectivity, which provides a great application prospect for the construction of DA sensing platform.

The effect of applied electric field on the micromorphology of Pt nanoparticles synthesized by laser ablation.

In the present study, laser ablation technique (Nd:YAG) has been applied to synthesize platinum nanoparticles (NPs). Also, the effect of applied electric field on the physical, structural, and morphological properties of Pt NPs has been investigated during the nanosecond pulsed laser ablation of platinum. Based on the results extracted from TEM and scanning electron microscopy images, the formation of high percentage of NPs with spherical shape is demonstrated in all samples. The increase of applied electric field creates few rectangular, hexagonal, and rhombic NPs with the average size decreased from 20 to 9nm. The significant influence of increasing electric field is also observed in UV-vis spectra by appearing the blue shift of the localized surface plasmon resonance peak. The UV-vis spectra also confirm the metallic nature of Pt NPs and the existence of inhomogeneous-sized particles and the coagulation of particle because of the long tail in higher wavelengths. In addition, atomic force microscopy images have been analyzed through MountainsMap Premium program and fractal dimension. As can be seen, increasing the applied electric field make the surface more irregular and the maximum value of Df reveals the most irregular topography for sample with 50 V/cm electric field. Finally, the bending and stretching frequencies of the functional bending groups connected to the NPs surface have been characterized by Fourier transform infrared spectroscopy. Electrical field-assisted laser ablation in liquids method allows a better control of the size, morphology, structure, and chemical composition of nanoparticles.

Characterization and electrochemical properties of Pt nanoparticles deposited on titanium oxide nanofibers

To overcome problems with carbon corrosion, titanium oxide nanofibers (TNFs) were investigated as alternative supports for the deposition of Pt nanoparticles. In this work, pristine or Nb-doped TNFs were prepared using an electrospinning technique. Pt nanoparticles were deposited on the selected TNFs using a microwave-assisted polyol method. Nb doping and heat treatment in reducing atmospheres significantly affected the fiber diameter, grain size, oxygen vacancies, and electrical conductivity of the TNFs. The incorporation of Nb into the TiO2 lattice inhibited grain growth and phase transition in an oxidizing atmosphere. However, heat treatment in a reducing atmosphere resulted in a significant increase in grain size. As a result of Nb doping associated with heat treatment at 800 °C in a reducing atmosphere, all the anatase phase was converted to the rutile phase. In addition, Ti4+ was reduced to Ti3+, and Nb5+ was reduced to Nb4+. These transformations could be the basis for high electrical conductivity. The electrochemical surface area (ECSA) of Pt/Nb-TNF800 was 48 m2/g. The durability of the ECSA of this material was much distinguished compared to that of a commercial Pt/C catalyst.

Preparation of Pt anchored on cerium oxide and ordered mesoporous carbon tri-component composite for electrocatalytic oxidation of adrenaline.

The preparation of Pt/cerium oxide and highly ordered mesoporous carbon (Pt/CeO2/OMC) nanohybrids is reported. CeO2 can be used as an active material that enhances the electrocatalytic properties of Pt nanoparticles. OMC exhibits excellent electrical conductivity and large specific surface area, which makes it a highly promising electrocatalyst support. Benefiting from the synergistic effects of the catalytic performance of Pt/CeO2 and excellent conductivity of OMC supports, the new nanocomposite of Pt/CeO2/OMC are able to create novel features of electrocatalytic activities. Pt/CeO2/OMC tri-component composite was used as an excellent sensing platform for the determination of adrenaline. The developed sensor exhibited excellent activity and convincing analytical performance towards adrenaline, such as wide linear range, high sensitivity, low limit of detection, and low limit of quantification. In addition, the recoveries ranging from 93.4 to 103.6% were obtained in human serum samples. The successful preparation of Pt/CeO2/OMC tri-component composite may promote the development of novel electrocatalyst and facilitate the design of new electrochemical sensors.

Improved LSPR Properties of Ag–Pt and Pt Nanoparticles: A Systematic Study on Various Configurations and Compositions of NPs via the Solid-State Dewetting of Ag–Pt Bilayers

The localized surface plasmon resonance (LSPR) of noble metal nanoparticles (NPs) has become an important research topic in various fields and can be systematically tuned to obtain the desired device performance through the appropriate structural and elemental modifications. In this research, the improved LSPR properties of Pt NPs and diverse configurations and compositions of Ag–Pt bimetallic alloy NPs were demonstrated on sapphire (0001) via the solid-state dewetting (SSD) of Ag–Pt bilayers. A strong and dynamic LSPR response in the ultraviolet (UV) and visible (VIS) regions was demonstrated depending on the elemental composition and surface morphology of the NPs, which is discussed along with finite difference time domain (FDTD) simulations. In comparison, the Ag–Pt NPs exhibited stronger LSPR excitation, whereas the Pt NPs showed a relatively weaker and broader response. Meanwhile, the Pt NPs fabricated in this study still demonstrated a much-enhanced LSPR response compared to previous studies on the solid-state dewetting of pure Pt films due to improvements in configuration, uniformity, and interparticle gaps. Various surface morphologies of NPs, such as connected nanoclusters, elongated NPs, and isolated spherical NPs, were obtained on the basis of alloying, diffusion, Rayleigh instability, and a surface minimization mechanism, which were different from those of pure Ag and Pt NPs in similar growth conditions. Particularly, one-step annealing of an Ag–Pt bilayer yielded Ag–Pt alloy NPs below 600 °C, which subsequently transformed into pure Pt NPs above 650 °C, in which the high diffusivity and high vapor pressure of Ag atoms significantly facilitated the overall growth process of the NPs.

Hydrogen sensors based on Pt-decorated SnO2 nanorods with fast and sensitive room-temperature sensing performance

Hydrogen energy has been regarded as one of the most promising green and renewable energy in future society. The development and application of fast and cost-effective hydrogen sensors are of great significant for the safe application of hydrogen energy. In this work, high-performance semiconductor hydrogen sensors with fast room-temperature (RT) hydrogen response were fabricated by using Pt-decorated SnO2 nanorods. The SnO2 nanorods with tetragonal phase were synthesized through a hydrothermal method, and then decorated by Pt nanoparticles by a photochemical reduction method under UV irradiation. The hydrogen sensing performance of the SnO2 nanorods at RT were greatly enhanced after the Pt-decoration. The sensor response was gradually increased from 27.10% to 87.35% with Pt/Sn mol ratio increasing from 0 to 3.63%. Meanwhile, the response and recovery process were also accelerated with increasing Pt loading amount. The room-temperature response and recovery time of the sensor with Pt/Sn ratio of 3.63% was down to 0.33 and 29.60 s, respectively. The sensor also exhibited outstanding repeatability and selectivity against CO and CH4. Moreover, the impact of humidity on the sensor performance were also investigated. The sensor response was decreased with increasing environmental humidity, which could be partially recovered after the humidity was decreased. The remarkably accelerated sensor performance could be attributed to the catalytic property of Pt nanoparticles with spillover effect and the contribution of Pt-induced metal-semiconductor contact effect to the hydrogen response of the sensors.

Searching for efficient defect types in carbon nanofibers to promote supported Pt catalytic activity for dehydrogenation reaction

• Three CNFs with different defective degrees are synthesized and identified. • N-doping of CNFs is implemented using in-situ synthesis and post treatment methods. • Thermal treatment of N-doped CNFs is adopted for generating edge-like defects. • Pt catalysts supported over various CNFs display different catalytic activity in dehydrogenation. • Edges and edge-like defects in CNFs are proven to be the most efficient active sites in catalysis. Three kinds of carbon nanofibers (CNFs) with different microstructures: platelet CNFs (CNFs-P), fishbone CNFs (CNFs-F) and tubular CNFs (CNFs-T) were synthesized as Pt catalyst supports for decalin dehydrogenation to release hydrogen. Different types of defects including doped nitrogen and edge-like sites were purposefully introduced into three pristine CNFs by employing N-doping and thermal treatment methods. The defective properties of the CNFs were identified by combining the intensity ratio and full width at half maximum of D and G bands derived from Raman spectra of the CNFs. It was revealed together with XPS analysis of Pt 4f 7/2 binding energy that the electronic property of Pt nanoparticles is very sensitive to the surface defect density of CNF supports. Further catalytic performance evaluation showed that Pt supported on the CNFs-P which are featured of the largest quantity of exposed edge sites can provide the most proper electronic property of the catalyst due to suitable metal-support interaction, thereby affording the highest catalytic activity. Moreover, N-doping by both in-situ synthesis and post-treatment manner can favor the Pt catalysts on the tubular and fishbone CNFs to increase their activity, but do harm to the activity of the Pt/CNFs-P. Thermal treatment of N-doped CNFs can generate new edge-like defects by removing N-species, thus beneficial to the activity of Pt catalysts on either tubular or fishbone CNFs. Therefore, the edge sites and edge-like defects on the surface of CNFs are proven to be the best ones, which can promote the catalytic activity of the supported Pt nanoparticles for the dehydrogenation reaction efficiently.

Solution-processed dual-layer Pt-SiO2 core-shell nanoparticles for nanocrystal memory with multi-bit storage states

We developed all-solution-processed dual-layer high-density Pt-SiO2 core-shell nanoparticles with ultra-thin interparticle layers within a uniform HfO2 matrix for application of nanocrystal memory. This device exhibited a clear step-like capacitance-voltage behavior at low operation voltage and four level states with a good retention property. Such a high memory performance could be attributed to the well-defined layer memory structure, high quality of the shell of nanoparticles and the interparticle layer between nanoparticle rows, appropriate nature property of Pt nanoparticles, and good material combinations of device structure. This sub-nanometer thick interparticle layer was successfully prepared through the self-assembly 3-aminopropyltrimethoxysilane (APTMS) mediated SiO2 layer, which was critical for superior multilayered device. The study result also infers Pt nanoparticles have good potential for nano-device application. We demonstrated this low-cost solution process with a low thermal budget provided a reliable approach to fabricate multilayered nanoparticle-based devices with tunable material, structure, and performance. It offers a high potential application of solution-processed nanocomposite devices for nanoparticle-based electronics.

Study of the optical and structural properties of Pt nanoparticles prepared by laser ablation as a function of the applied electric field

Pt NPs have attracted much attention because of their applications in many aspects such as the electronics industry, fuel cells, cancer therapy, etc. The influence of the applied electric field on the formation of platinum NPs by laser (Nd:YAG, λ = 1064 nm) ablation technique was investigated, for the first time. The TEM images showed that at higher values of the electric field, a variety of shapes like rectangular, hexagon, and rhombic were appeared besides the spherical NPs, as confirmed by SEM investigations. By increasing the applied electric field, the average size of Pt NPs decreased from 20 to 9 nm. In addition, from the XRD spectra, the mean crystalline size, crystal structure, d-spacing, and lattice parameters of NPs were calculated. On the basis of the optical absorption spectra of NPs, we observed a size-dependent blue shift of the SPR peak position when the value of the electric field increased from 0 to 20 V/cm. To identify the stretching and bending frequencies of the molecular functional groups attached to the NPs surface, Raman and FT-IR spectroscopy was applied.

Support induced charge transfer effects on electrochemical characteristics of Pt nanoparticle electrocatalysts

The electrokinetic properties of Pt nanoparticles supported on Carbon (Pt/C) and Boron Carbide-Graphite composite (Pt/BC) are compared over a wide potential range. The influence of the support on the electronic state of Pt was investigated via in-situ X-ray Absorption Spectroscopy. Pt d-band filling, determined from XANES white line analysis, was lower and nearly constant between 0.4 and 0.95V vs. RHE for Pt/BC, indicating more positively charged particles in the double layer region and a delay in the onset of oxide formation by about 0.2V compared to the Pt/C catalyst, which showed a marked increase in d-band vacancies above 0.8V vs. RHE. Moreover, Δμ analysis of the XANES data indicated a lack of sub-surface oxygen for the Pt/BC catalyst compared to the Pt/C catalyst above 0.9V vs. RHE. Additional anion adsorption on the Pt/BC in the double layer region, detected by CO displacement, was also confirmed by XANES analysis of the d-band occupancy. The H2 oxidation activities of electrodes with low catalyst loadings were assessed under high mass transport conditions using the floating electrode methodology. The metal-support interaction between the Pt and BC support improved the maximum hydrogen oxidation current density by 1.4 times when compared to Pt/C.

Active Site Elucidation and Optimization in Pt Co‐catalysts for Photocatalytic Hydrogen Production over Titania

AbstractPlatinum co‐catalysts play a critical role in promoting the photocatalytic performance of inorganic semiconductors, yet despite intensive investigation, the active platinum species responsible remains controversial. Here, the physicochemical properties of Pt nanoparticles introduced into anatase titania through three different synthetic protocols are investigated by porosimetry, XRD, X‐ray photoelectron spectroscopy (XPS), and X‐ray absorption spectroscopy (XAS) and correlated with their corresponding activity for aqueous photocatalytic hydrogen production. Conventional wet impregnation produces small but highly oxidized platinum nanoparticles owing to the classical strong metal–support interaction with titania during high‐temperature processing. Photodeposition yields predominantly metallic but large and inhomogeneous (1.5–7.5 nm) Pt nanoparticles. In contrast, a modified in situ polyol route affords metallic and highly dispersed (<2 nm) nanoparticles with minimal PtOx. Photocatalytic H2 evolution is directly proportional to the surface concentration of Pt metal, conclusively demonstrating metallic platinum as the active co‐catalyst, and offering a simple parameter to quantitatively predict the photocatalytic performance of Pt/TiO2 in H2 production. The modified in situ polyol synthesis is optimal for co‐catalyst formation, delivering rate enhancements of 25–80 % compared with the other syntheses.

A low temperature butane gas sensor used Pt nanoparticles-modified AZO macro/mesoporous nanosheets as sensing material

This paper reported the synthesis and gas-sensing properties of Pt nanoparticles modified Al-doped ZnO (AZO) macro-/mesoporous nanosheets, which were prepared via a solution combustion approach with a subsequent heat treatment at 400°C for 50min. The high performance in detecting butane were achieved for the well-adhered products with unique porous surface appearance on the sensors fabricated using indirect heating method, which demonstrated the superiority of solution combustion synthesis (SCS) in synthesizing complex oxides. The possible explanations of the high butane gas-sensing characteristics of these sensors were based on the results of BET and XPS. The large surface area could provide sufficient interface between the materials and butane gas, and the adsorbed oxygen species having strong oxidation activity could break the butane molecules into CO2 and H2O. The gas-sensing properties of Pt-modified AZO were investigated by testing the gas responses towards butane. The maximum response of the 5% Pt-AZO based gas sensor reached 56.52–3000ppm butane at 200°C. What’s more, the sensor also exhibited good short- and long-term stability, repeatability and selectivity, which made it a potential candidate in the application of monitoring butane. In the end, the possible mechanisms of gas-sensing properties were discussed.

Platinum nanoparticles supported on nitrobenzene-functionalised graphene nanosheets as electrocatalysts for oxygen reduction reaction in alkaline media

A systematic study on the electrocatalytic properties of Pt nanoparticles supported on nitrobenzene-modified graphene (Pt-NB/G) as catalyst for oxygen reduction reaction (ORR) in alkaline solution was performed. Graphene nanosheets were spontaneously grafted with nitrophenyl groups using 4-nitrobenzenediazonium salt. The electrocatalytic activity towards the ORR and stability of the prepared catalysts in 0.1M KOH solution have been studied and compared with that of the commercial Pt/C catalyst. The results obtained show that the NB-modified graphene nanosheets can be good Pt catalyst support with high stability and excellent electrocatalytic properties. The specific activity of Pt-NB/G for O2 reduction was 0.184mAcm−2, which is very close to that obtained for commercial 20wt% Pt/C catalyst (0.214mAcm−2) at 0.9V vs. RHE. The Pt-NB/G hybrid material promotes a four-electron reduction of oxygen and can be used as a promising cathode catalyst in alkaline fuel cells.

Electron transfer dependent catalysis of Pt on N-doped carbon nanotubes: Effects of synthesis method on metal-support interaction

The influence of catalyst synthesis strategy, including ethylene glycol (EG) reduction, sodium borohydride reduction and impregnation-H2-reduction, on the metal-support-interaction of Pt on nitrogen-doped carbon nanotubes (Pt/NCNTs) was systematically investigated and summarized. The catalytic performances were explored in the electro-oxidation reactions of glycerol, formic acid and CO, and the hydrolysis of ammonia borane (AB). Through X-ray photoelectron spectroscopy (XPS), density functional theory calculations and CO stripping technique, it was revealed that the synthesis methods drastically affected the electronic property of Pt nanoparticles (NPs). Pt NPs preferentially interacted with graphitic nitrogen in EG reduction method due to the electron donating property of graphitic nitrogen, while preferentially interacted with pyridinic nitrogen and defects in the impregnation-H2-reduction method due to the vacancies containing NP favoring the charged metal ion adsorption. The catalytic activity strongly depended on the electronic property of Pt NPs, which can be ascribed by the binding energy of Pt4f7/2(0) from XPS. The higher catalytic activity was obtained over electron-enriched Pt NPs for the electro-oxidation reactions. On the other hand, electron-deficient Pt NPs had better intrinsic activity in AB hydrolysis. The results herein suggested that appropriate synthesis method should be rationally applied to maximize the activities of Pt for targeting reactions benefited from electron-enriched or electron-deficient metal NPs.

Bifunctional property of Pt nanoparticles deposited on TiO2 for the photocatalytic sp3C–sp3C cross-coupling reactions between THF and alkanes

Photocatalytic direct cross-coupling between THF and alkanes was accelerated by Pt nanoparticles on TiO2, as a receiver for photoexcited electron and a metal catalyst.

Microwave assisted synthesis of Sn-modified MgAlO as support for platinum catalyst in cyclohexane dehydrogenation to cyclohexene

This paper described an investigation on catalytic properties of Pt nanoparticles supported on hydrotalcite-like oxide (MgAl(Sn)O) calcinated by microwave for cyclohexane dehydrogenation to cyclohexene. The PtSn catalysts were investigated with several state-of-art characterizations such as BET, XRD, NH3-TPD, H2-TPR, H2-TPD and XPS. Particular emphasis was focused on the changes in the Sn-support interaction and in the character of Pt active sites. H2-TPR showed that the microwave calcination strengthened the interaction between Sn and support. The strengthened interaction could maintain more amounts of Sn in oxidized. H2-TPD revealed that microwave calcination facilitated Sn in changing the interfacial character between Pt and support. This was beneficial for the migration of carbonaceous materials to the support. These effects resulted in higher activity and stability in cyclohexane dehydrogenation to cyclohexene.

Synthesis and Properties of Platinum Nanoparticles by Pulsed Laser Ablation in Liquid

Platinum (Pt) nanoparticles were synthesized by pulsed laser ablation in liquid (PLAL) technique in different liquids (acetone, ethanol, and methanol). Ablation was performed using a Q-switched Nd:YAG laser with output energy of 230 mJ/pulse for 532 nm wavelength. Ablation time and laser energy fluence were varied for all the liquids. Effects of laser energy fluence, ablation time, and nature of the liquid were reported. The mean size, size distributions, shape, elemental composition, and optical properties of Pt nanoparticles synthesized by PLAL were examined by transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and UV-Visible absorption spectroscopy.

Biosynthesis of silver and platinum nanoparticles using orange peel extract: characterisation and applications.

This study focuses on the green synthesis of noble metal nanoparticles (silver (Ag) and platinum (Pt)) and how the size and shape of the nanoparticles produced can be controlled through changes in the initial pH value of the precursor solution. The nanoparticles were characterised by ultra-violet-visible spectroscopy, transmission electron microscopy and X-ray diffraction. This simple and environmentally friendly method allows the synthesis of diverse nanostructures in the absence of a surfactant or polymer to direct nanoparticle growth, and without externally adding seed crystallites. The antibacterial effects of Ag nanoparticles and catalytic properties of Pt nanoparticles were explored for future promising biotechnological approaches in different fields.

Mechanisms of Enhanced Electrocatalytic Activity for Oxygen Reduction Reaction on High-Index Platinum n(111)-(111) Surfaces.

Oxygen reduction reactions (ORRs) on high-index planes of Pt n(111)-(111) were studied by density functional theory (DFT). The stepped surfaces, where n = 2, 3, and 4, showed that O2, O, and OH exhibited higher binding energies along the step compared to the terrace plane. The Pt atoms along the step can become distorted through the binding of the O and OH, where the shift in position of the Pt atoms is the largest along the stepped sites, hence forming stronger bonds with O atoms. One of the two O atoms produced from the bond dissociation of O2 will push the other one down a step with lower binding energies, consequently reducing the energy required for the protonation reaction (O + H(+) → OH, and OH + H(+) → H2O). The quicker recovery back to the clean Pt surface would therefore improve the catalytic properties of Pt nanoparticles, especially those with exposure to high-indexed facets.

Effect of microwave calcination on catalytic properties of Pt/MgAl(Sn)Ox catalyst in cyclohexane dehydrogenation to cyclohexene

This paper describes an investigation on catalytic properties of Pt nanoparticles supported on MgAl(Sn)Ox mixed oxide for cyclohexane dehydrogenation to cyclohexene. The MgAl(Sn)Ox supports were synthesized by microwave calcined hydrotalcite-derived precursors, and Pt/MgAl(Sn)Ox catalysts were prepared by an incipient wetness impregnation method. The catalysts were characterized by X-ray diffraction (XRD), hydrogen temperature-programmed reduction (H2-TPR), hydrogen temperature-programmed desorption (H2-TPD), X-Ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM). The results showed that the microwave calcination changed the interfacial character between Pt and support, and strengthened the interaction between tin and support, and facilitated the high dispersion of Pt nanoparticles presented on the support. These effects resulted in higher activity, stability and cyclohexene selectivity in cyclohexane dehydrogenation to cyclohexene.