Platinum Doping Research Articles

Gold versus platinum for chemical modification of carbon quantum dots from carboxymethyl cellulose: Tunable biomedical performance

Urgent requirements for medication from chronic inflammation and cancer are considerably interested, while, the recent reports were considered with investigating simple methods for synthesis. Metal-modified carbon quantum dots (“M-CQDs”) were successfully ingrained from carboxymethyl cellulose under the assistance of infra-red irradiation. The current approach demonstrates a study for the effect of structural tuning for biomedical performance of CQDs via modifying of CQDs with either gold (Au-CQDs) or platinum (Pt-CQDs). Successive nucleation of Au-CQDs and Pt-CQDs was confirmed via different instrumental analyses like, TEM micrographs, Zeta potential, XRD, FTIR, 1HNMR&13CNMR spectra. The data reveal that, modification of CQDs (8.7 nm) with gold was reflected in insignificant effect on the mean size of CQDs (8.9 nm), whereas, doping of platinum resulted in slight enlargement of the size (12.4 nm). However, Pt-CQDs were exhibited with the highest anti-inflammatory (cell viability percent 78 %) and antimicrobial action. On the other hand, Au-CQDs were shown with the highest anticancer affinity (reduction of cell viability 83 %) compared to the others. The current study approved the superiority of CQDs modified with either gold or platinum to be successfully applicable as potential therapeutic reagents for the treatment of either cancer or inflammation diseases.

Influence of platinum content (X) in the LaNi5PtX catalyst and reaction conditions on the properties of ferromagnetic Ni-filled CNTs

This research highlights the synthesis of carbon nanostructures using the catalytic chemical vapor deposition (CCVD) method, a hybrid process combining chemical vapor deposition (CVD) and Gas-Solid Heterogeneous Catalysis (GSHC). Intermetallic catalysts, LaNi5Ptx (x = 0, 0.05, 0.5, 1.0), were fabricated through an arc melting procedure to serve as templates for the catalytic conversion of carbon precursors into solid materials. These catalysts, featuring the ferromagnetic transition metal Ni, tend to aggregate into larger particles, reducing the rate of hydrocarbon cracking at the catalyst surface. Rare earth metals like Lanthanum were introduced to form an alloy with a higher melting point to prevent thermal aggregation. Additionally, Pt was incorporated to modify the catalytic properties of the alloy. The study primarily explores the impact of catalyst composition on carbon nanotube (CNT) production. The introduction of platinum content to the catalyst influences the rate at which Ni is filled. The research aimed to alter the catalyst's composition by varying platinum doping in the Pauli paramagnetic lanthanum nickel alloy (LaNi5) to understand the growth mechanism and morphological variations of Ni-filled CNTs. Platinum and lanthanum oxides significantly influence nickel filling in CNTs, resulting in an increased filling rate as the catalyst's Pt content varies from 0 to 1.0. However, higher Pt doping content disrupts the CNT structure with spontaneous nickel encapsulation.

Neighboring Platinum Atomic Sites Activate Platinum-Cobalt Nanoclusters as High-Performance ORR/OER/HER Electrocatalysts.

The rational design of efficient and multifunctional electrocatalysts for energy conversion devices is one of the major challenges for clean and renewable energy transition. Herein, the local electronic structure of cobalt-platinum nanoclusters is regulated by adjacent platinum atomic site encapsulated in N-doped hollow carbon nanotubes (PtSA -PtCo NCs/N-CNTs) by pyrolysis of melamine-orientation-induced zeolite imidazole metal-organic frameworks (ZIF-67) with thimbleful platinum doping. The introduction of melamine can reactivate adjacent carbon atoms and initiate the oriented growth of nitrogen-doped carbon nanotubes. The systematic analysis suggests the significant role of thimbleful neighboring low-coordinated Pt─N2 in altering the localized electronic structure of PtCo nanoclusters. The optimized PtSA -PtCo NCs/N-CNTs-900 exhibit excellent hydrogen evolution reaction (HER)/oxygen evolution reaction (OER)/oxygen reduction reaction (ORR)/ catalytic performance reaching the current density of 10mA cm-2 in 1m KOH under the low 47 (HER) and 252mV (OER) overpotentials, and a high half-wave potential of 0.86 and 0.89V (ORR) in 0.1m KOH and 0.1m HClO4 , respectively. Remarkably, the PtSA -PtCo NC/N-CNT-900 also presents outstanding catalytic performances toward water splitting and rechargeable Zn-air batteries. The theoretical calculations reveal that optimal regulation of the electronic structure of PtCo nanoclusters by thimbleful neighboring Pt atomic reduces the reaction energy barrier in electrochemical process, facilitating the ORR/OER/HER performance.

Triggering electrode multi-catalytic activity for reversible symmetric solid oxide cells by Pt-doping lanthanum strontium ferrite

Among the up-and-coming technologies, reversible solid oxide cells (r-SOCs) represent a highly efficient way to store and convert energy using a single device. The interchangeability between SOFC and SOEC operation is the key aspect, though for its technological advancement the development of performing, versatile and robust electrodes must be pursued. A multi-purpose catalyst would allow for the design of a reversible symmetric cell (r-SSOC), greatly reducing fabrication and maintenance costs. However, such a flexible electrode material must comply with the requirements of both SOC electrodes, namely ensuring high performance in a wide pO2 range: catalytic activity towards fuel oxidation and H2O/CO2 reduction, electronic and ionic conductivity, long-term stability, tolerance to carbon deposition. In this work, platinum doping at the B-site of a lanthanum strontium ferrite (LSFPt) endowed the parent perovskite with superior versatility, making it able to operate as oxygen exchange catalyst as well as fuel electrode material. 5-mol% Pt inclusion enhanced the ORR/OER activity, lowering the LSF area-specific resistance by 29% and approaching the state-of-the-art LSCF performance. After reduction, Pt-Fe finely distributed exsolution provided the fuel electrode with catalytically active sites. LSFPt-symmetric H2-SOFCs and CO2-SOECs, displayed 720 mW∙cm−2 power density and 1.66 A·cm−2 current density at 1.6 V, respectively, at 850 °C. Endurance tests on LSFPt-based r-SSOCs demonstrated a remarkably stable SOFC/SOEC cyclability and a steady current density output for over 370 h in 50:50 CO2:CO at 850 °C.

Pt Modified Sb2Te3 Alloy Ensuring High-Performance Phase Change Memory.

Phase change memory (PCM), due to the advantages in capacity and endurance, has the opportunity to become the next generation of general−purpose memory. However, operation speed and data retention are still bottlenecks for PCM development. The most direct way to solve this problem is to find a material with high speed and good thermal stability. In this paper, platinum doping is proposed to improve performance. The 10-year data retention temperature of the doped material is up to 104 °C; the device achieves an operation speed of 6 ns and more than 3 × 105 operation cycles. An excellent performance was derived from the reduced grain size (10 nm) and the smaller density change rate (4.76%), which are less than those of Ge2Sb2Te5 (GST) and Sb2Te3. Hence, platinum doping is an effective approach to improve the performance of PCM and provide both good thermal stability and high operation speed.

Physical properties of superconducting Ca10(Pt4As8)((Fe0.92Pt0.08)2As2)5 crystal and comprehensive cognition on the transition temperature for Ca10-3(4)-8

Superconducting single crystal of Ca10(Pt4As8)((Fe0.92Pt0.08)2As2)5 has been prepared using flux method, and the physical properties of which are careful examined. Resistivity anisotropy between ab plane and c-axis is observed, T −0.5 term originated from the interlayer Josephson coupling is essential to be added to the formula used to describe the out-of-plane resistivity. The density of state (DOS) value at Fermi level derived from the fitting of specific heat data is consistent with the calculation results. Both direct and indirect platinum doping effect have influences on the superconducting transition temperature (Tc) of Ca 10-3(4)-8 system, the Tc of our sample falls well into the trend strip formed by the data reported previously.

Effect of Pt doping on sensing performance of g-C3N4 for detecting hydrogen gas: A DFT study

Detection of hydrogen is critical for its applications as high density renewable energy. Graphitic carbon nitrides show great potential with excellent sensitivity and fast response for hydrogen detection, however, the sensing mechanism is unclear. In this work, density functional theory is used to investigate the lattice parameters, electron density and electron transfer of platinum-doped graphitic C3N4 upon the adsorption of hydrogen, and its hydrogen gas detection and selectivity is analyzed and discussed. For Pt-doped g-C3N4, hydrogen molecule shows the maximum adsorption energy of −1.83 eV compared with those for carbon dioxide and methane, and its bands gap reduces from 0.84 to 0.62 eV after the adsorption, suggesting obvious selective sensitivity towards hydrogen gas. Moreover, the doping of platinum promotes the interaction between hydrogen and doped surface. The competing reactions of oxygen gas leads to relatively strong impact on the adsorption of hydrogen, while the incorporations of hydrogen oxide, carbon dioxide and nitrogen generally result in limited influence on hydrogen adsorption.

Effect of single atom Platinum (Pt) doping and facet dependent on the electronic structure and light absorption of Lanthanum Titanium Oxide (La2Ti2O7): A Density Functional Theory study

Charge generation and separation are two key processes for semiconductor photocatalysis. Here, we use Pt as a single atom catalyst to systematically examine the facet-dependent electronic band structure and light absorption of the layered perovskite-type wide-gap semiconductor, lanthanum titanium oxide (La2Ti2O7, LTO) by means of density functional theory simulations. It is found that single Pt atom doping of different LTO surfaces (here, (100), (101) and (001)) can not only create states in the bandgap that would promote the formation of recombination centers, but also shift the optical absorption edge to the visible region. Interestingly, the Pt doping forms a heterojunction, with the valence band maximum consisting of Pt states and the conduction band minimum consisting of LTO states, respectively. To study the facet dependent surface activity, acetic acid (CH3COOH) was used as a model molecule to investigate the adsorption and charge transfer on the (101), (100) and (001) Pt-LTO surface facets. The results show that the (101) facet could enable stronger adsorption of CH3COOH by promoting more electron transfer during the interfacial interaction. Our theoretical findings aim to promote the design and optimization of the single atom catalysts (SACs) for photocatalytic applications and other broad catalysis systems.

A platinum-doped ZnO-based LPG sensor with high sensitivity

In environment air quality monitoring, toxic and flammable gas detection plays an important role. Due to the extreme concern for safety standards in industrial and residential applications, real-time observation of toxic gas and notification of inadvertent leaks is necessary. This paper delves into a simple and cost-effective way for fabricating extremely sensitive zinc oxide (ZnO) thin film gas sensors for the detection of Liquefied Petroleum Gas (LPG) at low concentrations. Sol-gel method is used to fabricate the ZnO thin films. Platinum (Pt) nanoparticles have been placed on the semiconducting material to behave as catalysts in order to enhance sensing performance. The platinum doping is done via the RF Sputtering technique. For different concentration of LPG, the variation in electrical resistance of a semiconductor material was evaluated. Sensor characterization was carried out using XRD, and FESEM. ZnO thin films are optimized at different thickness varying from 70 nm to 550 nm. Then annealing of thin films of ZnO is carried out at temperatures range from 450 °C to 675 °C. LPG shows a maximum response for thin film of 170 nm annealed at 625 °C, at operating temperature of 150 °C, for 1000 ppm concentration. Sensing response for ZnO thin film has been enhanced to 2.586 post doping which was 1.896 for annealed bare ZnO thin film. Comparing to bare ZnO thin films, there had been a significant improvement in sensor response with platinum doped ZnO thin films.

Manipulating the electronic properties of CNT by doping metal

Carbon nanotube (CNT) has received tremendous attention for potential use in many field due to its excellent physicochemical properties. However, the application performance derived from the electronic properties has remained a great challenge. Motivated by the electronic property of CNT, metal (M) such as silver (Ag), gold (Au) or platinum (Pt) doping effect on the electronic properties of CNT was investigated here. The hydroxyl-functionalized-CNT (OH-CNT) was taken as the model and the electronic of OH-CNT-Mn (Mn means metal clusters, n = 1~4) were studied based on first-principles. The formation of Ag-O bond makes the energy gap always present in OH-CNT-Agn and the energy gap of OH-CNT-Aun cases with even atomic Au cluster disappears. However, only Pt-C bonds are formed and the energy gap is gradually reduced to no gap in OH-CNT-Ptn. This theoretical study at the electronic level can give an idea for the research on the properties of metal-based CNT materials.

Performance of platinum doping on spent alkaline battery-based catalyst for complete oxidation of o-xylene.

Oxidation of o-xylene was performed using alkaline battery-based catalyst doped with platinum to investigate the properties and activities. O-xylene was selected as the model of volatile organic compound (VOC) in this work. Physicochemical properties of the selected catalysts were characterized by FE/TEM (field emission transmission electron microscopy), BET (Brunauer-Emmett-Teller) analysis, XRD (X-ray powder diffraction), SEM/EDX (scanning electron microscopy/energy dispersive X-ray spectroscopy), and H2-TPR (hydrogen temperature programmed reduction). Major elements of the spent alkaline battery-based catalyst treated with sulfuric acid solution [SAB (400) catalyst] were manganese, zinc, iron, oxygen, carbon, chlorine, aluminum, sodium, silicon, and potassium. Increasing the doping amount of platinum on SAB (400) catalyst from 0.1 to 1 wt% increased particle size of platinum and lowered the temperature of TPR (TTP) for SAB (400) catalyst. Better redox properties were achieved with an increase in the o-xylene conversion according to the doping amount of platinum. When GHSV (gas hourly space velocity) was 40,000 h-1, o-xylene was oxidized completely over SAB (400) catalyst and 1.0 wt% Pt/SAB(400) catalyst at temperatures of 400 °C and 280 °C, respectively.

The effect of palladium and platinum doping on the structure, stability and optical properties of germanium clusters: DFT study of PdGen and PtGen (n = 1–20) clusters

Structural, electronic and optical properties of germanium clusters doped with palladium and platinum atoms MGen (M = Pd,Pt and n = 1–20) are investigated in the framework of the density-functional theory. From n ≥ 10 or 11, the cage-like structures where the doping atom is totally encapsulated inside a Gen cage are favored. Relative stabilities of different MGen clusters have been analyzed from the average binding energies, second energy differences, HOMO–LUMO gap, and the vertical ionization potential and electronic affinity. Our results show that the clusters of MGen (M = Pd,Pt) with n = 10, 12, 16 and 18 exhibit relative high stability. Optical absorption spectra are predicted to be unable to discriminate the endohedral and exohedral structures.

Influences of platinum doping concentrations and operation temperatures on oxygen sensitivity of Pt/SnO2/Pt resistive gas sensors

Influences of surface platinum (Pt) doping concentrations and operation temperatures on oxygen sensing properties of Pt/SnO2/Pt metal–semiconductor–metal (MSM) resistive gas sensors were investigated incorporating structural and chemical variations. Although tetragonal phase dominated crystallographic structure of the virgin film, it was observed that the triclinic phase with minor peak intensities was also present. With increasing the doped Pt concentration, the triclinic phase of the SnO2 cannot be detected due to diffusion of the Pt into the SnO2 lattices. Surface particle sizes increased up to 200 nm and relative porosity of the film surface almost enhanced with increasing the Pt concentrations. Oxygen deficient and chemically metastable phase of the SnxOy was transformed to SnO2 with the Pt addition due to catalytic effects of the Pt. Different vibrational modes became active depending on the Pt content which was due to the stretching of the SnO2 bonds. In addition, the resistivity of the Pt-doped SnO2 films increased with the Pt additions. The oxygen sensitivity of the sensor increased with increasing both the Pt concentrations and operation temperatures. The optimum operation temperature was found to be 335 °C. Interestingly, as operation temperature exceeds to 225 °C, high Pt concentration decreased the sensor sensitivity. In addition, selectivity of the MSM sensor changes with the Pt additions. The obtained results have depicted that the parameters used in the sensor fabrication and operation should be carefully selected to increase sensing properties of the MSM resistive gas sensors.

Efficient Blue Phosphorescent OLEDs with Improved Stability and Color Purity through Judicious Triplet Exciton Management

AbstractHighly efficient and stable blue phosphorescent organic light‐emitting diodes are achieved by employing a step‐wise graded doping of platinum(II) 9‐(pyridin‐2‐yl)‐2‐(9‐(pyridin‐2‐yl)‐9H‐carbazol‐2‐yloxy)‐9H‐carbazole (PtNON) in a device setting. A device employing PtNON demonstrates a high peak external quantum efficiency (EQE) of 17.4% with an estimated LT70 lifetime of over 1330 h at a brightness of 1000 cd m−2. PtNON is then investigated as a “triplet sensitizer” in an alternating donor–acceptor doped emissive layer to further improve the device emission color purity by carefully managing an efficient Förster resonant energy transfer from PtNON to 2,5,8,11‐tetra‐tert‐butylperylene as a selected acceptor material. Thus, such OLED devices demonstrate an EQE of 16.9% with color coordinates of (0.16, 0.25) and an estimated luminance (LT70) lifetime of 628 h at a high brightness of 1000 cd m−2.

Methanol oxidation on pure and platinum-doped tungsten oxide supported by activated carbon

Abstract Thin films of pristine and platinum-doped tungsten oxide were examined as potential catalysts for efficient partial oxidation of methanol. The tungsten oxide layers with different thicknesses were deposited by the means of reactive magnetron sputtering on oxidized silicon wafer and silicon coated with carbon activated via ion etching. Morphology and chemical analysis were checked before and after the reaction by X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM). It was found that while pure tungsten oxide layers on silicon exhibit relatively small hydrogen production rates and high ratio of carbon oxides, both etched carbon interlayer (as long as the oxide thickness is low enough) and platinum doping can lead to significant improvement of reactivity, increasing hydrogen yield and decreasing fraction of undesired carbon monoxide in the product mix. It is suggested that it is due to the strong electronic interaction between WOx and Pt or active C, increasing the acidity of the tungsten oxide reaction sites and thus altering its reactivity preference from methanol dehydration towards dehydrogenation. If both species are present in a very thin oxide, however, the competing electronic interactions lead to partial reduction of their positive effect. As prepared sputtered thin films are chemically and morphologically unstable under reducing environment of methanol oxidation reaction, but the presence of dispersed Pt in the layer substantially stabilizes its physical structure.

Enhancing oxygen and hydrogen evolution activities of perovskite oxide LaCoO3 via effective doping of platinum.

In this study, a series of perovskite oxides LaCo1−xPtxO3−δ (x = 0, 0.02, 0.04, 0.06, and 0.08) were prepared by the citric acid–ethylenediaminetetraacetic acid (CA–EDTA) complexing sol–gel method and characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). Then, the samples were investigated as OER and HER bifunctional electrocatalysts in alkaline media. Compared with other catalysts, LaCo0.94Pt0.06O3−δ had good stability and presented more activity at a lower overpotential of 454 mV (at 10 mA cm−2), a lower Tafel slope value of 86 mV dec−1 and a higher mass activity of 44.4 A g−1 for OER; it displayed a lower overpotential of 294 mV (at −10 mA cm−2), a lower Tafel slope value of 148 mV dec−1 and a higher mass activity of −34.5 A g−1 for HER. The improved performance might depend on a larger ECSA, faster charge transfer rate and higher ratio of the highly oxidative oxygen species (O22−/O−). Furthermore, the eg orbital filling of Co approaching 1.2 in the B site might play a leading role.

Effect of Platinum Doping on the Morphology and Sensing Performance for CuO-Based Gas Sensor

Pristine and Pt-doped CuO nano-flowers were synthesized by a simple water bath heating method in this paper. Highly sensitive hydrogen sulfide (H2S) gas sensors based on Pt-doped CuO nano-flowers were fabricated. Scanning electron microscopy, X-ray diffraction, inductively coupled plasma atomic emission spectrometry, and energy dispersive X-ray spectroscopy were used to examine the characteristics and morphology of materials. The sensing performances of sensors with different concentrations of Pt dopants were evaluated at different operating temperatures. The results indicated that the CuO sensor doped with 1.25 wt % Pt exhibited the highest response (Rg/Ra, where Rg is the resistance in gas, and Ra is the resistance in air) of 135.1 to 10 ppm H2S at 40 ∘C, which was 13.1 times higher than the response of a pure CuO sensor. Pt doping also plays an important role for the enhancement of H2S selectivity against C2H5OH, NH3, H2, CH3COCH3, and NO2.

Facile synthesis of high-surface area platinum-doped ceria for low temperature CO oxidation

Using a simple slow decomposition method of nitrate precursors, high-surface area platinum-doped ceria with a crystallite size of 9 nm can be prepared. The catalytic performance of the compound can be tuned by changing the reduction temperature under hydrogen (300 °C, 500 °C and 700 °C). The catalyst treated at 300 °C shows the best catalytic performance, being active at room temperature. The materials were analysed using a combination of structural characterization methods (X-ray diffraction (XRD), nitrogen physisorption, high angle annular dark field scanning transmission electron microscopy (HAADF-STEM)), surface sensitive methods (X-ray photoelectron spectroscopy (XPS), H2-chemisorption and H2-temperature-programmed reduction (TPR)) and X-ray absorption fluorescence spectroscopy (XAFS). HAADF-STEM and XAFS analysis suggests successful doping of platinum in the ceria lattice. After pretreatment at 300 °C, the situation is slightly different. While no defined platinum nanoparticles can be identified on the surface, some platinum is in a reduced state (XPS, H2-chemisorption).

Platinum doping effect on In2O3MSM IR photodetectors

The un-doped and platinum-doped In2O3 thin films were deposited for the investigation of platinum doping effect on the structural, morphological and electrical properties of In2O3 based metal-semiconductor-metal infrared photodetectors. The In2O3 metal-semiconductor-metal infrared photodetectors were also fabricated for obtaining the electrical characteristics such as the carrier recombination lifetime, diffusion length, carrier density, mobility, saturation current, barrier height, series resistance and ideality factor. It was seen from the characterization results that the Pt dopant usage has a prominent effect on properties of In2O3 metal-semiconductor-metal infrared photodetectors which are not extensively studied in the literature.

Catalytic oxidation of diesel soot particulates over Pt substituted LaMn1-xPtxO3 perovskite oxides

Present paper deals with the preparation (by sol-gel method) and characterization (by H2-TPR, XPS, XRD, IR, SEM, TEM) of the Pt substituted LaMn1-xPtxO3 (x = 0,0.05,0.1,0.2,0.3) perovskite oxides and their activities towards the diesel soot oxidation at simulated atmosphere. The results show platinum enters the perovskite crystal structure when x＜0.1. With the increase of platinum doping amount, the oxygen vacancy concentration on the catalyst surface increases, and H2-TPR shows that the low-temperature oxidation-reduction performance of the catalyst is improved with the increase of platinum doping amount. Catalytic oxidation of soot was studied under tight contact with soot/catalyst ratio of 1/10 under a flow rate of air at 100 ml/min. LaMn0.8Pt0.2O3 perovskite catalyst was found to give the best result for soot oxidation with the light off temperatures T10 = 339 °C, T50 = 370 °C, T90 = 405 °C. The might reaction mechanism is also presented.