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Active new ceria-promoted platinum supported on ZSM-5 catalysts were prepared and characterized by X-ray diffraction (XRD), Fourier transform infrared spectra (FTIR), transform electron microscopy (TEM), temperature programmed desorption (TPD), and FTIR of CO adsorption. The samples were prepared by the incipient wetness impregnation method and calcined at 500 °C. The XRD patterns and FTIR spectra prove that the zeolite framework is kept unaltered after metal loadings. TEM images prove the presence of Pt nanoparticles with particle size starting from 14 to 27 nm. The FTIR data suggest the formation of Pt–O–Ce linkage. In-situ FTIR of CO adsorption over reduced samples proves the presence of Pt0 only, and no Ptn+–CO species are detected. The prepared catalysts were tested in both oxidation reaction (CO oxidation) in the gas phase and in reduction reaction (4-nitrophenol reduction) in the aqueous medium. Firstly, CO oxidation by O2 results in the formation of a CO2 peak at 2347 cm−1 as the only CO oxidation product in the studied frequency range. The intensity of the CO2 peak increases after the addition of Ce, and it is 4 times higher in Pt1Ce0.5ZSM-5 than that in the Ce-free sample. According to the FTIR data and previous reports, the increase in the catalytic activity may be due to the formation of Pt–O–Ce linkage. Secondly, Ce-promoted Pt1ZSM5 also exhibits enhanced catalytic activity towards the reduction of 4-nitrophenol to 4-aminophenol by NaBH4 in the aqueous medium. The first-order rate constant of the reduction increases ≈13 times after incorporating equal ratios of Pt and Ce (Pt1Ce1ZSM-5), and the activation energy (Ea) decreases to 40% of that in the reaction over Pt1ZSM-5.

The present research work discusses the influence of platinum nanoparticles on the catalytic activity of Cu/TiO2 catalysts for soot, formaldehyde, and carbon monoxide oxidation. The results showed that the size of the platinum nanoparticles, loaded on the Cu/TiO2 nanostructure, varied from 1 to 2 nm. The Pt-Cu/TiO2 catalyst exhibited effective catalytic performance in the oxidation of formaldehyde at 25 °C (99% of conversion), CO at 100 °C (90% of conversion) and soot at 300 °C (100% of conversion) due to the platinum particle size and Pt-Cu interaction, which developed Ti3+ and oxygen vacancies on TiO2. Moreover, the bimetallic catalyst consisted of a complex mixture of Cu2+, Cu1+, and Pt0 species. The Pt-Cu/TiO2 catalyst showed stability in the three different reactions from 20 to 300 °C.

In this work, platinum nanoparticles (Pt) decorated on a spinel group, zinc cobalt oxide (ZnCo2O4) 3-D flower was intended to detect caffeine electrochemical sensor. Pt particles were used to enhance the performance of hydrothermally prepared 3-D ZnCo2O4 flower. So Pt nanoparticles were decorated on each thin nanosheet of self-assembled 3-D flower-like ZnCo2O4. The thin transparent nanosheet of the ZnCo2O4 flower will benefit electrochemical sensors by simplifying its ion exchange. Therefore, Pt@ZnCo2O4 shows an excellent electrochemical conductivity, which promotes the caffeine-based sensor's rapid electrochemical oxidation. Using amperometric i-t at an applied potential of 1.45 V, Pt@ZnCo2O4 modified electrode shows widespread of two linear ranges (0.05 to 265.55 μM and 295.55 to 757.55 μM) with a low detection limit (0.0114 and 0.01657 μM) and high sensitivity (3.419 and 1.862 μA μM−1 cm−2). Moreover, good results were obtained for the real-time detection of caffeine in sugar-free cola beverage and energy drink samples. Henceforth, the developed method could be an ideal way to detect caffeine in real samples.

Reverse microemulsion-based synthesis was successfully applied to the preparation of nanosized TiO2 particles in anatase and rutile crystalline phases. The resulted nano-oxides were found to have smaller average crystalline size, higher surface area and narrower band gap than commercial TiO2 samples, P25 and DT-51. All the TiO2 materials were used as supports for platinum nanoparticles prepared by incipient wetness impregnation and deposition-precipitation methods. The photo-catalytic activities of these materials were compared in the reaction of glycerol photo-reforming in aqueous media using simulated solar light. The results showed that different crystalline phases of titania have different effects on hydrogen production and selectivity of intermediate products. Anatase was found to be more selective towards glyceraldehyde, while the presence of rutile promoted a more selective reaction towards glycolaldehyde. Rutile also exhibited a higher productivity of hydrogen compared to anatase.

Efforts to selectively convert polypropylene (≈30 % of all plastic waste) have not been particularly successful. Typical distributions span from gas to solid products, highlighting a challenging cleavage control. Here, carbon-supported platinum nanoparticles were designed for complete hydrocracking into liquid hydrocarbons (C5 -C45 ). The metal and carrier phases operated synergistically. The cleavage activity depended on platinum and its rate rose with decreasing particle size. The carbon carrier controlled selectivity via hydrocarbon binding strength, which depended on the chain length and on the surface oxygen concentration. An optimal binding provided by carbons with high oxygen content promoted both adsorption of long chains and desorption of short products. This strategy achieved an unprecedented 80 % selectivity toward motor oil (C21 -C45 ). Carbons exhibiting too strong binding (low oxygen content) hindered product desorption, while non-binding materials (e. g., silica or alumina) did not promote plastic-Pt contact, leading in both cases to low performance. This work pioneers design guidelines in a key process towards a sustainable plastic economy.

Behavior of Pt/C catalysts obtained by the platinum deposition on standard and nitrogen-doped carbon supports with different microstructure has been studied in the oxygen electroreduction reaction in an acidic electrolyte. The catalysts based on the modified supports are characterized by a uniform spatial distribution of small-sized (1.5–2 nm) Pt nanoparticles over the surface of the supports, which results in high values of the electrochemically active surface area (110–130 m2 g− 1 (Pt)). The use of various stress testing protocols has shown that the Pt/C material based on the N-doped KetjenBlack EC DJ-600 possesses the highest mass activity and durability, which noticeably exceed the corresponding characteristics of the commercial HiSPEC3000 catalyst.

The application of direct methanol fuel cells is hampered by not only low activity but also poor stability and CO tolerance of Pt catalyst. The electrocatalytic activity and stability of platinum nanoparticles assembled on different kinds of flower-like CeO2 (fCeO2)/[Graphene (G), Carbon Vulcan (XC-72) and Ordered Mesoporous Carbon (CMK-3)] composite supports for methanol electro-oxidation were investigated. The catalyst samples were characterized by X-ray diffraction, scanning electron microscopy (SEM), transmission electron microscopy, and X-ray photoelectron spectroscopic. The electrochemical properties of the catalysts were measured by a three electrode system on electrochemical workstation (IVIUM). The results show that the Pt grain size of Pt-fCeO2/G catalyst is the smallest. Compared with Pt-fCeO2/XC-72 and Pt-fCeO2/CMK-3, Pt-fCeO2/G has the lowest binding energies of Pt(0) and more hydroxyl, carbonyl, carboxyl and other oxygen-containing functional groups. This kind of oxygen-containing functional group can facilitate methanol oxidation and relieve CO poisoning. The mass-specific activity of Pt-fCeO2/G is 2.2 and 3.6 times higher than that of Pt-fCeO2/CMK-3 and Pt-fCeO2/XC-72, respectively. The activation energy of Pt-fCeO2/G catalyst for electrocatalytic oxidation methanol is the lowest, which is 16.63 kJ mol−1. Pt-fCeO2/G appears to be a promising and cost effective methanol oxidation anode catalyst.

Poly(N-isopropylacrylamide) (PNIPAM) nanogels were prepared by emulsion polymerization using sodium dodecyl sulfate (SDS) and employed as a capping agent in platinum nanoparticle (Pt NP) synthesis by liquid-phase reduction with hydrogen gas. When the PNIPAM nanogels were used without removing SDS, that is, a slight amount of SDS was included in the reaction solution, Pt nanocubes (NCs) were predominantly produced (>80%). The proportion of the resultant Pt NCs was much higher than that obtained using the PNIPAM linear polymer (∼60%). To clarify the effects of the three-dimensional polymer network and SDS, we synthesized Pt NPs using the PNIPAM nanogel without SDS (SDS-free PNIPAM nanogel) and found that Pt NCs are rarely formed, and most NPs obtained have an irregular shape. When only SDS was used as a capping agent, NCs were hardly obtained, but other polyhedral NPs were formed. Furthermore, the use of SDS together with the PNIPAM polymer led to the decrease in the proportion of the Pt NCs compared with that obtained using only the linear polymer. These results indicate that the enhancement of the Pt NC proportion using the PNIPAM nanogel with SDS is attributable to not only the three-dimensional polymer network of the PNIPAM nanogel but also the assist of SDS as a capping agent.

Synthesis of platinum nanoparticles intercalated between layers of commercially available graphite powder samples possessing surface area values ranging from 20 to 750 m2 g-1 was attempted by the insertion of platinum chloride between the layers followed by hydrogen reduction. Platinum nanosheets with 1-4 nm thickness and 5-300 nm width and hexagonal holes were obtained for the graphite powder with 20 m2 g-1 independent of the platinum loadings (5, 10, and 15 wt%). Platinum nanosheets with the similar size (1-4 nm thickness and 5-300 nm width) and hexagonal holes were formed for graphite powder with 120 and 300 m2 g-1 with only 15 wt% platinum loading, but not for 5 and 10 wt% platinum loadings. Interestingly, for the graphite powder with higher surface area of 500 and 750 m2 g-1, platinum nanosheets were not formed. Platinum nanosheets intercalated between graphite samples were evaluated for cinnamaldehyde hydrogenation in supercritical carbon dioxide solvent. High cinnamyl alcohol selectivity was obtained for the platinum nanosheets intercalated between graphite layers having surface area of 20 m2 g-1; however, hydrocinnamaldehyde selectivity was high for the platinum nanosheets intercalated between graphite samples having surface area of 120 m2 g-1.

Cefepime and Meropenem are the new class of antibiotics, which are particularly used as last potent defender or the antibiotics of the last resort against multi-resistant bacterial species. In this paper, an impedance-based electrochemical biosensor was fabricated for identifying antibiotics of last resort in the forensic samples including gastric lavage and other body fluids. The sensor was developed using platinum nanoparticles (PtNPs) and electrodeposited zinc oxide- zinc hexacyanoferrate hybrid film (ZnO/ZnHCF) on the surface of a fluorine-doped glass electrode (FTO). Further, penicillinase was immobilized onto the modified electrode using penicillinase enzyme. The developed biosensor exhibits a good analytical response for the detection of antibiotics evaluated using electrochemistry studies. The linear response of the fabricated electrode was observed from 0.1 to 750 µM and the electrode limit of detection (LOD) was observed as 0.1 µM. The sensor confirms good accuracy, is highly selective, and sensitive for the target. While storing the modified electrode at 4 °C, the stability of biosensor was evaluated for 45 days, and activity loss of 30-40% was observed. The highly sensitive interface of Penicillinase@CHIT/PtNP-ZnO/ZnHCF/FTO electrode shows a promising future in forensic studies.

In brain tumors, neurotransmitters and platinum drugs may have some interaction, but their role in radiation therapy remains unclear. We investigated the effects of dopamine in combination with platinum on human glioblastoma U-251MG cells upon X-ray irradiation, comparing with L-DOPA, 2-phenylethylamine and temozolomide. Cell proliferation of U-251MG cells was prominently decreased by dopamine in combination with 10 μM platinum upon 4 Gy of X-ray irradiation, accompanied with intracellular reactive oxygen species generation and mitotic catastrophe. Platinum alone did not increase intracellular reactive oxygen species. On the other hand, L-DOPA in combination with platinum did not decrease cell proliferation regardless of X-ray irradiation. It was clearly shown that 2-phenylethylamine did not suppress cell proliferation as compared to dopamine. Temozolomide decreased cell proliferation in a dose-dependent manner upon X-ray irradiation. However, the combined administration of temozolomide and platinum did not further decrease cell proliferation. The platinum nanoparticles were gradually taken up by cells after administration as determined by ICP analysis. Our results suggest that platinum-coexisting dopamine led cells to mitotic catastrophe due to increased production of intracellular reactive oxygen species which was boosted by X-ray and platinum-catalyzed auto-oxidation of dopamine, and thereby cell proliferation was suppressed. In addition, normal human fibroblast OUMS-36T-1 cells were subjected to experiments. Regarding the effect of the combined administration of dopamine and platinum on each cell which was exposed to X-ray, cell proliferation was decreased in U-251MG cells by the combined administration of platinum, whereas that was not decreased in OUMS-36T-1 cells. This provides one basic insight into the effects of dopamine in combined with platinum on radiation therapy for glioblastoma.

In this work, platinum(0) nanoparticles are deposited on the surface of magnetic cobalt ferrite forming magnetically separable Pt-0/CoFe2O4 nanoparticles, which are efficient catalysts in H-2 generation from the hydrolysis of ammonia borane. Catalytic activity of Pt-0/CoFe2O4 nanoparticles decreases with the increasing platinum loading, parallel to the average particle size. Pt-0/CoFe2O4 (0.23% wt. Pt) nanoparticles have an average diameter of 2.30 +/- 0.47 nm and show an extraordinary turnover frequency of 3628 min(-1) in releasing 3.0 equivalent H-2 per mole of ammonia borane from the hydrolysis at 25.0 degrees C. Moreover, the magnetically separable Pt-0/CoFe2O4 nanoparticles possess high reusability retaining 100% of their initial catalytic activity even after ten runs of hydrolysis. The superb catalytic activity and outstanding reusability make the Pt-0/CoFe2O4 nanoparticles very attractive catalysts for the hydrogen generation systems in portable and stationary fuel cell applications. (C) 2021 Elsevier Inc. All rights reserved.

Nanoparticle catalyst materials are becoming ever more important in a sustainable future. Specifically, platinum (Pt) nanoparticles have relevance in catalysis, in particular, fuel cell technologies. Sputter deposition into liquid substrates has been shown to produce nanoparticles without the presence of air and other contaminants and the need for precursors. Here, we produce Pt nanoparticles in three imidazolium-based ionic liquids and PEG 600. All Pt nanoparticles are crystalline and around 2 nm in diameter. We show that while temperature has an effect on particle size for Pt, it is not as great as for other materials. Sputtering power, time, and postheat treatment all show slight influence on the particle size, indicating the importance of temperature during sputtering. The temperature of the liquid substrate is measured and reaches over 150 °C during deposition which is found to increase the particle size by less than 20%, which is small compared to the effect of temperature on Au nanoparticles presented in the literature. High temperatures during Pt sputtering are beneficial for increasing Pt nanoparticle size beyond 2 nm. Better temperature control would allow for more control over the particle size in the future.

The development of a new platinum nanocatalyst to maximize the catalytic efficiency of the precious noble metal catalyst in releasing hydrogen from ammonia borane (AB) is reported. Platinum(0) nanoparticles are impregnated on a reducible cobalt(II,III) oxide surface, forming magnetically isolable Pt0/Co3O4 nanocatalysts, which have (i) superb catalytic activity providing a record turnover frequency (TOF) of 4366 min-1 for hydrogen evolution from the hydrolysis of AB at room temperature and (ii) excellent reusability, retaining the complete catalytic activity even after the 10th run of hydrolysis reaction. The outstanding activity and stability of the catalyst can be ascribed to the strong interaction between the platinum(0) nanoparticles and reducible cobalt oxide, which is supported by the results of XPS analysis. Pt0/Co3O4 exhibits the highest TOF among the reported platinum-nanocatalysts developed for hydrogen generation from the hydrolysis of AB.

The green synthesis of platinum nanoparticles between 3 and 7 nm was achieved using an aqueous extract, and then supported on high surface area carbon obtained from the pyrolysis of the same natural source, which is finally used as an electrocatalyst for the oxygen reduction reaction (ORR). The green synthesis is achieved by using a Sargassum sp. extract with a PtCl4 solution, which is confirmed through a UV–vis analysis. The electrocatalysts obtained are characterized by X-ray diffraction (XRD), Field Emission Scanning Electron Microscopy (FESEM), Transmission Electron Microscopy (TEM). The electrochemical characterization is determined in acidic media. The PtNPs (5% w/w) supported on commercial carbon Vulcan showed an excellent electrocatalytic activity up to 6.3 mA cm−2 (at 0.2 V vs. RHE), in comparison to the commercial catalyst Pt-Vulcan. Finally, the PtNPs supported on the Sargassum sp. carbon-based sample improve the kinetics of the ORR as it increases the amount of PtNPs loading.

Cyclic voltammetry (CV) is a powerful and popular electrochemical technique widely used to study the surface structure of materials through the electrochemical behaviors. Herein CV is utilized to study the electrochemical deposition of selenium (Se) on carbon black-supported Pt nanostructures. We synthesized carbon-loaded platinum nanoparticles (Pt/C) by microwave method and studied the electrochemical behavior of selenium on them. Through the experiment of changing the reverse potential, the corresponding relationship between the Se deposition peak and stripping peak was clarified and the deposition and stripping process of Se was proposed. Meanwhile, we synthesized cubic and octahedral nanocrystals of Pt, and used CV to study the Se deposition on these nanosctructures supported by carbon. It was found that the relative intensity of UPD peaks on Pt is different, as Ptcube@C is dominated by (100) and Ptoct@C electrode is dominated by (111) while Pt@C falls in between.

This work presents the synthesis of platinum and silver nanoparticles obtained on a support composed of the S-layer protein (SLP) isolated from Lactobacillus kefiri and polyurethane particles (PU). The support was obtained by adsorption of the protein on the polymer particles in aqueous dispersion. After combining the support with the platinum or silver salts and subsequently reducing with hydrogen, noble metal-based heterogeneous bionanocatalysts were obtained. Platinum or silver nanoparticles with diameters dn = 4.9 nm (ds = 4.9 nm; dv/dn = 1.05) or dn = 8.0 nm (ds = 10.6 nm; dv/dn = 1.63), respectively, were observed by TEM on the surface of the protein/polymer supports. Both nanocatalysts showed excellent catalytic activity in the reduction of p-nitrophenol with NaBH4 at room temperature, with conversions of 100% and 97% for platinum and silver bionanocatalysts, respectively. Noteworthy, both bionanocatalysts maintain their activity until 4 reuse cycles, being the platinum-based system the one showing the best performance. These results demonstrated that the developed bionanocatalysts are promising and emerging alternatives in the field of supported noble metal nanoparticle-based heterogeneous catalysts.

In this study, we report the hydrogen sensing properties of the Pt dispersed graphitic carbon nitride (g-C3N4) nanocomposite at room temperature and inert atmosphere. The nanocomposite was synthesized by a wet-chemical approach, where melamine and chloroplatinic acid hexahydrate were used as precursors. The fabrication of the sensor was done by jet nebulizer-based spray pyrolysis setup. Various characterizations were performed for the analysis of the synthesized nanocomposite. Electrical resistance in the presence and absence of the analyte gas was drastically different. The results at different concentrations and film thickness show Pt/g-C3N4 to possess good sensitivity towards the hydrogen gas, suggesting that it could be used for reliable hydrogen gas sensing.

Effecting the synergistic function of single metal atom sites and their supports is of great importance to achieve high-performance catalysts. Herein, we successfully fabricate polyoxometalates (POMs)-stabilized atomically dispersed platinum sites by employing three-dimensional metal-organic frameworks (MOFs) as the finite spatial skeleton to govern the accessible quantity, spatial dispersion, and mobility of metal precursors around each POM unit. The isolated single platinum atoms (Pt1) are steadily anchored in the square-planar sites on the surface of monodispersed Keggin-type phosphomolybdic acid (PMo) in the cavities of various MOFs, including MIL-101, HKUST-1, and ZIF-67. In contrast, either the absence of POMs or MOFs yielded only platinum nanoparticles. Pt1-PMo@MIL-101 are seven times more active than the corresponding nanoparticles in the diboration of phenylacetylene, which can be attributed to the synergistic effect of the preconcentration of organic reaction substrates by porous MOFs skeleton and the decreased desorption energy of products on isolated Pt atom sites., It is of great significance to exert the synergistic effect between single atom and support. Here, the authors prepare polyoxometalates-stabilized single-atom site catalysts in confined space with enhanced activity for alkynes diboration.

Platinum–carbon catalysts are widely used in the manufacturing of proton-exchange membrane fuel cells. Increasing Pt/C activity and stability is an urgent task and the optimization of their structure seems to be one of the possible solutions. In the present paper, Pt/C electrocatalysts containing small (2–2.6 nm) nanoparticles (NPs) of a similar size, uniformly distributed over the surface of a carbon support, were obtained by the original method of liquid-phase synthesis. A comparative study of the structural characteristics, catalytic activity in the oxygen electroreduction reaction (ORR), and durability of the synthesized catalysts, as well as their commercial analogs, was carried out. It was shown that the uniformity of the structural and morphological characteristics of Pt/C catalysts makes it possible to reduce the negative effect of the small size of NPs on their stability. As a result, the obtained catalysts were significantly superior to their commercial analogs regarding ORR activity, but not inferior to them in terms of stability.

This work has to purpose decrease the value of the cell potential (Ecell) of an electrochemical reactor with a separate compartment with an anionic membrane designed for electro-leaching electronic waste (E-waste). In the anodic compartment using a titanium plate in HNO3 as an anolyte, while the electro-leaching of the metals and the evaluation of the oxygen evolution reaction (OER) was studied. Three different cathodes (Platinum; Pt, titanium coated with ruthenium oxide; RuO2|Ti and titanium coated with platinum nanoparticles; nPt/C|Ti) were used for the catalysis of the evolution reaction of hydrogen (HER) in a solution of H2SO4. The results obtained by voltammetry indicate that the electrodes modified with RuO2 and nPt/C, promote a greater cathodic current for the HER, decreasing the cell potential and increase the current density of the induced metallic electro-leaching. This implies the decrease of the electrical power that the reactor requires during its operation. Obtaining Space-time yield (STY) values of 123.4 and 64 mol·L-1·h-1·cm-2 for the carbon and platinum nanoparticle and the ruthenium oxide catalysts respectively.

Understanding the size- and shape-dependent properties of platinum nanoparticles is critical for enabling the design of nanoparticle-based applications with optimal and potentially tunable functionality. Toward this goal, we evaluated nine different empirical potentials with the purpose of accurately modeling faceted platinum nanoparticles using molecular dynamics simulation. First, the potentials were evaluated by computing bulk and surface properties-surface energy, lattice constant, stiffness constants, and the equation of state-and comparing these to prior experimental measurements and quantum mechanics calculations. Then, the potentials were assessed in terms of the stability of cubic and icosahedral nanoparticles with faces in the {100} and {111} planes, respectively. Although none of the force fields predicts all the evaluated properties with perfect accuracy, one potential -- the embedded atom method formalism with a specific parameter set -- was identified as best able to model platinum in both bulk and nanoparticle forms., 20 pages, 8 figures

Carbon materials have been widely utilized as supports in different catalytic reactions; however, it has been rarely reported that carbon supports were used in the catalytic oxidation of volatile organic compounds because they have no catalytic activity and poor catalytic stability compared to metal supports. Herein, fabricating optimal carbon supports to facilitate the catalytic oxidation of benzene has become a great concern of research. A novel activated carbon (biomass–HCO) was prepared from different waste biomass via a three-stage route without the participation of harmful chemical reagents. The successful synthesis of C–O bonds and C═O bonds through this method could greatly increase oxygen-enriched functional groups and defects of the biomass–HCO surface, which could effectively promote the nucleation and growth of platinum. Benzene oxidation reactions were performed to evaluate the activity of catalysts. The results demonstrated that Pt/biomass–HCO catalyst made the reaction temperature sharply decrease to 160 °C at T₉₀. The 150 h on-stream reaction exhibited great thermal stability of Pt/biomass–HCO. The DFT calculations verified the strong interaction between Pt nanoparticles and carbon supports. Moreover, our demonstration of the superior benzene oxidation activity of Pt/biomass–HCO catalysts revealed that it is feasible to utilize oxygen-enriched biomass carbon as catalytic supports toward the oxidation of volatile organic compounds.

Shape-controlled platinum nanoparticles exhibit extremely high oxygen reduction activity. Platinum nanoparticles were synthesized by the reduction of a platinum complex in the presence of a soft template formed by organic surfactants in oleylamine. The formation of platinum nanoparticles was investigated using in situ small-angle X-ray scattering experiments. Time-resolved measurements revealed that different particle shapes appeared during the reaction. After the nuclei were generated, they grew into anisotropic rod-shaped nanoparticles. The shape, size, number density, reaction yield, and specific surface area of the nanoparticles were successfully determined using small-angle X-ray scattering profiles. Anisotropic platinum nanoparticles appeared at a low reaction temperature (∼100 °C) after a short reaction time (∼30 min). The aspect ratio of these platinum nanoparticles was correlated with the local packing motifs of the surfactant molecules and their stability. Our findings suggest that the interfacial structure between the surfactant and platinum nuclei can be important as a controlling factor for tailoring the aspect ratio of platinum nanoparticles and further optimizing the fuel cell performance.

Understanding the formation of nanomaterials down to the atomic level is key to rational design of advanced materials. Despite their widespread use and intensive study over the years, the detailed formation mechanism of platinum (Pt) nanoparticles remains challenging to explore and rationalize. Here, various in situ characterization techniques, and in particular X-ray total scattering with pair distribution function (PDF) analysis, are used to follow the structural and chemical changes taking place during a surfactant-free synthesis of Pt nanoparticles in alkaline methanol. Polynuclear structures form at the beginning of the synthesis, and Pt-Pt pair distances are identified before any nanoparticles are generated. The structural motifs best describing the species formed change with time, e.g., from [PtCl5-PtCl5] and [PtCl6-Pt2Cl6-PtCl6] to [Pt2Cl10-Pt3Cl8-Pt2Cl10]. The formation of these polynuclear structures with Pt-Pt coordination before the formation of the nanoparticles is suggested to account for the fast nucleation observed in the synthesis.

The bioavailability of dissolved Pt(IV) and polyvinylpyrrolidone-coated platinum nanoparticles (PtNPs) of five different nominal hydrodynamic diameters (20, 30, 50, 75, and 95 nm) was characterized in laboratory experiments using the model freshwater snail Lymnaea stagnalis. Dissolved Pt(IV) and all nanoparticle sizes were bioavailable to L. stagnalis. Platinum bioavailability, inferred from conditional uptake rate constants, was greater for nanoparticulate than dissolved forms and increased with increasing nanoparticle hydrodynamic diameter. The effect of natural organic matter (NOM) composition on PtNP bioavailability was evaluated using six NOM samples at two nanoparticle sizes (20 and 95 nm). NOM suppressed the bioavailability of 95 nm PtNPs in all cases, and DOM reduced sulfur content exhibited a positive correlation with 95 nm PtNP bioavailability. The bioavailability of 20 nm PtNPs was only suppressed by NOM with a low reduced sulfur content. The physiological elimination of Pt accumulated after dissolved Pt(IV) exposure was slow and constant. In contrast, the elimination of Pt accumulated after PtNP exposures exhibited a triphasic pattern likely involving in vivo PtNP dissolution. This work highlights the importance of PtNP size and interfacial interactions with NOM on Pt bioavailability and suggests that in vivo PtNP transformations could yield unexpectedly higher adverse effects to organisms than dissolved exposure alone.

We report, for the first time, polypyrrole-derived nitrogen-containing tubular hollow carbon (NTHC) frameworks for hydrogen (H2) gas sensing application. NTHC was synthesized simply by pyrolysis of tubular polypyrrole nanostructure, which developed carbon nanostructure of high surface area with numerous micromesopores. The surface of the carbon nanostructure was uniformly decorated with platinum nanoparticles (Pt NPs). The Pt/NTHC sensor, fabricated using a facile drop-casting method, shows good repeatability and complete recovery at room temperature and achieves twofold higher sensitivity compared to Pt NPs dispersed multiwalled carbon nanotubes. The sensor shows interesting gas sensing behavior (conversion of p-type to n-type) during exposure to H2. The possible role of N-doping type in the sensing behavior is discussed.

Nanomaterials are materials in which at least one of the dimensions of the particles is 100 nm and below. There are many types of nanomaterials, but noble metal nanoparticles are of interest due to their uniquely large surface-to-volume ratio, high surface area, optical and electronic properties, high stability, easy synthesis, and tunable surface functionalization. More importantly, noble metal nanoparticles are known to have excellent compatibility with bio-materials, which is why they are widely used in biological applications. The synthesis method of noble metal nanoparticles conventionally involves the reduction of the noble metal salt precursor by toxic reaction agents such as NaBH4, hydrazine, and formaldehyde. This is a major drawback for researchers involved in biological application researches. Hence, the bio-synthesis of noble metal nanoparticles (NPs) by bio-materials via bio-reduction provides an alternative method to synthesize noble metal nanoparticles which are potentially non-toxic and safer for biological application. In this review, the bio-synthesis of noble metal nanoparticle including gold nanoparticle (AuNPs), silver nanoparticle (AgNPs), platinum nanoparticle (PtNPs), and palladium nanoparticle (PdNPs) are first discussed. This is followed by a discussion of these biosynthesized noble metal in biological applications including antimicrobial, wound healing, anticancer drug, and bio-imaging. Based on these, it can be concluded that the study on bio-synthesized noble metal nanoparticles will expand further involving bio-reduction by unexplored bio-materials. However, many questions remain on the feasibility of bio-synthesized noble metal nanoparticles to replace existing methods on various biological applications. Nevertheless, the current development of the biological application by bio-synthesized noble metal NPs is still intensively ongoing, and will eventually reach the goal of full commercialization.

The specific monitoring of serotonin (ST) has provoked massive interest in therapeutic and biological science since it has been recognized as the third most significant endogenous gastrointestinal neurotransmitter. Hence, there is a great need to develop a sensitive and low-cost sensing platform for the detection of a clinically relevant ST level in biological matrices. Herein, we develop a simple two-step approach for an ultrasensitive electrochemical (EC) sensor with the Cu2O metal oxide (MO)-incorporated CNT core that has been further deposited with a transitional amount of platinum nanoparticles (Pt NPs). We presented, for the first time, the deposition of Pt NPs on the (CNTs-Cu2O-CuO) nanopetal composite via the galvanic replacement method, where copper not only acts as a reductant but a sacrificial template as well. The electrocatalytic aptitude of the fabricated EC sensing platform has been assessed for the sensitive detection of ST as a proficient biomarker in early disease diagnostics. The synergy of improved active surface area, remarkable conductivity, polarization effect induced by Pt NPs on CNTs-Cu2O-CuO nanopetals, fast electron transfer, and mixed-valence states of copper boost up the redox processes at the electrode-analyte junction. The CNTs-Cu2O-CuO@Pt-modified electrode has unveiled outstanding electrocatalytic capabilities toward ST oxidation in terms of a low detection limit of 3 nM (S/N = 3), wide linear concentration range, reproducibility, and incredible durability. Owing to the amazing proficiency, the proposed EC sensor based on the CNTs-Cu2O-CuO@Pt heterostructure has been applied for ST detection in biotic fluids and real-time tracking of ST efflux released from various cell lines as early disease diagnostic approaches.

Ternary composite photocatalysts based on titania and solid solutions of CdS and ZnS were prepared and studied by a set of physicochemical methods including XRD, XPS, HRTEM, UV-vis spectroscopy, and electrochemical tests. Two synthetic techniques of platinization of Cd1−xZnxS/TiO2 were compared. In the first case, platinum was deposited on the surface of synthesized Cd1−xZnxS (x = 0.2–0.3)/TiO2 P25; in the second one, Cd1−xZnxS (x = 0.2–0.3) was deposited on the surface of Pt/TiO2 P25. The photocatalytic properties of the obtained samples were compared in the hydrogen evolution from TEOA aqueous solution under visible light (λ = 425 nm). The Cd1−xZnxS (10–50 wt%; x = 0.2–0.3)/Pt (1 wt%)/TiO2 photocatalysts demonstrated much higher photocatalytic activity than the Pt (1 wt%)/Cd1−xZnxS (10–50 wt%; x = 0.2–0.3)/TiO2 ones. It turned out that the arrangement of platinum nanoparticles precisely on the titanium dioxide surface in a composite photocatalyst makes it possible to achieve efficient charge separation according to the type II heterojunctions and, accordingly, a high rate of hydrogen formation. The highest photocatalytic activity was demonstrated by 20% Cd0.8Zn0.2S/1% Pt/TiO2 in the amount of 26 mmol g−1 h−1 (apparent quantum efficiency was 7.7%) that exceeds recently published values for this class of photocatalysts.

Selective oxidation of the secondary hydroxyl group of glycerol to dihydroxyacetone (DHA) is an extremely challenging yet important reaction. The main difficulty is that the three hydroxyl groups in glycerol are prone to randomly oxidize, resulting in an unsatisfactory DHA selectivity. We show here that an assembly of platinum nanoparticles (NPs, ∼2 nm) and N-stabilized single-atom bismuth (Bi), namely Pt/Bi@NC, shows a record-high DHA selectivity of ∼95.0% towards glycerol oxidation under optimized reaction conditions. Characterization and theoretical calculations confirm that single-atom Bi in the vicinity of Pt NPs provides a preferred site to chelate with the primary –OH of glycerol, and its secondary –OH is prone to bind to a surface Pt atom of a Pt NP with a shorter Pt–H bond length. This as-formed unique adsorption configuration of glycerol on the Pt–Bi dual site significantly facilitates the oxidation of the secondary –OH of glycerol, thus contributing to a record-high selectivity to DHA.

We propose the fabrication of a novel ready-to-use electrochemical sensor based on a screen-printed graphene paste electrode (SPGrE) modified with platinum nanoparticles and coated with a molecularly imprinted polymer (PtNPs@MIP) for sensitive and cost-effective detection of paraquat (PQ) herbicide. Successive coating of the PtNPs surface with SiO2 and vinyl end-groups formed the PtNPs@MIP. Next, we terminated the vinyl groups with a molecularly imprinted polymer (MIP) shell. MIP was attached to the PtNPs cores using PQ as the template, methacrylic acid (MAA) as the monomer, ethylene glycol dimethacrylate (EGDMA) as the cross-linker, and 2,2′-azobisisobutyronitrile (AIBN) as the initiator. Coating the SPGrE surface with PtNPs@MIP furnished the PQ sensor. We studied the electrochemical mechanism of PQ on the MIP sensor using cyclic voltammetry (CV) experiments. The PQ oxidation current signal appears at −1.08 V and −0.71 V vs. Ag/AgCl using 0.1 M potassium sulfate solution. Quantitative analysis was performed by anodic stripping voltammetry (ASV) using a deposition potential of −1.4 V for 60 s and linear sweep voltammetric stripping. The MIP sensor provides linearity from 0.05 to 1000 μM (r2 = 0.999), with a lower detection limit of 0.02 μM (at −0.71 V). The compact imprinted sensor gave a highly sensitive and selective signal toward PQ. The ready-to-use MIP sensor can provide an alternative approach to the determination of paraquat residue on vegetables and fruits for food safety applications.

Herein, a new type of highly-active platinum (Pt) nanoparticle encapsulated alumina-doped resorcinol–formaldehyde carbon composite (Al@RFC) is fabricated based on resorcinol–formaldehyde (RF) resin and aluminum acetylacetonate using a one-step carbonization approach and evaluated for an asymmetric hydrogenation (AH) reaction. The carbonization process of RF is essentially completed at 700 °C and resulted in Al@RFC with uniform and ordered porous structures. The Pt/Al@RFC catalysts are decorated with uniformly dispersed Pt nanoparticles of around 4 nm diameter over the Al@RFC support. The prepared catalysts are chirally modified with cinchonidine (CD) to explore the catalytic efficiency of AH of ethyl 2-oxo-4-phenylbutanoate (EOPB). The Pt/Al@RFC catalysts have substantially circumvented the shortcomings of poor repeatability of Pt/Al2O3 and low ee values of Pt/C catalysts, displaying conversion efficiencies and ee values of 99% and 82%, respectively. Furthermore, the catalyst could be reused 16 times. Notably, the optimized catalyst displayed turn-over frequency (TOF) values of more than 80 000 h−1, which is the highest reported activity in this hydrogenation reaction. Graphene formation during the high temperature (700 °C) carbonization process is proposed to play a role in its exceptionally high activity.

A novel sonochemical approach to synthesize platinum (Pt) nanoparticles has been developed to produce smaller, and more monodisperse particles than traditional chemical reduction methods such as the sodium borohydride (NaBH4) reduction method. It was also found that careful experimental manipulation of the ultrasonic conditions such as the ultrasonic frequency (f), the acoustic power (Pacoustic) and the solution volume (V) may be employed to tailor the sonochemical radical yield to the same value for two different ultrasonic systems (20 kHz provided by an ultrasonic probe or sonifier, and 408 kHz by an ultrasonic plate transducer) leading to a similar reduction rate, and as a consequence, to Pt-nanoparticles with similar sizes. The reduction of Pt(IV) was found to be a first order reaction with a rate constant (k) of 0.062 min−1 for both ultrasonic systems, and the particle sizes from TEM measurements were found to be (2.2 ± 0.5) nm and (2.3 ± 0.4) nm for the 20 kHz and the 408 kHz samples, respectively. In comparison, the chemical reduction method resulted in particle sizes of (3.0 ± 0.5) nm. It was also found that the sonochemical synthesis at 408 kHz was more efficient than at 20 kHz with an initial sonochemical efficiency of (0.20 ± 0.04) μmol kJ−1 at 408 kHz and (0.060 ± 0.004) μmol kJ−1 at 20 kHz. The sonochemical synthesis at 408 kHz also yielded nanoparticles of higher purity. Interestingly, direct sonication into the reaction vessel using the 20 kHz sonication probe produced impurities of Ti, V and Al in the solution, indicating that direct sonication at lower frequencies led to (i) probe material (made of Ti alloy – Ti-6Al-4V) erosion induced by cavitation and (ii) a continuous supply of micro meter sized impurities. It was also observed that the introduction of impurities increased the reduction rate constant of Pt(IV) through heterogeneous nucleation (k = 0.12 min−1) as was demonstrated for the 408 kHz system under controlled addition of Ti/Al/V seed microparticles. Direct sonication using a sonifier should therefore be avoided when high purity catalytic materials are required.

Effective transfer and utilization of the photogenerated electrons are a key factor for achieving highly efficient H2 generation by photocatalytic water splitting. Apart from the activity of the co-catalyst, the interface between the co-catalyst and semiconductor is of particular importance. Guided by DFT calculations, single-atom (SA) Pt doped carbon nitride (CN) is successfully synthesized for use as the co-catalyst to the semiconducting CuS. The catalyst system (Pt1-CN@CuS) exhibits an enhanced photocatalytic performance for water splitting with a H2 production rate of 25.4 μmol h-1 and an apparent quantum yield (AQY) of 50.3 % under the illumination of LED-530. Solar-to-hydrogen (STH) conversion efficiency is calculated to be 0.5 % under AM 1.5 illumination. This is the very first investigation of SA as the co-catalyst, which decreases the overpotential of CN during the water splitting and lowers interfacial resistance of the catalyst/co-catalyst and co-catalyst/electrolyte.

Efficient dehydrogenation of cyclohexane at low temperatures is of great importance in the field of liquid organic hydrogen carriers (LOHCs). In this paper, a series of Pt nanoparticles with a size...

Toluene (TL)/methylcyclohexane (MCH) is an attractive organic hydride couple for secure storage and transportation of large amounts of hydrogen. Electrochemical hydrogenation of TL to MCH can achie...

An efficient method for the deposition of ionic platinum species PtOx onto a TiO2 surface was developed on the basis of light-induced activation of the [Pt(NO3)6]2- anion. The deposited PtOx species with an effective Pt oxidation state between +4 and +2 have an oxygen-made environment and include single ion centers {PtOn} and polyatomic ensembles {PtnOm} connected to a TiO2 surface with Pt-O-Ti bonds. The resulting PtOx/TiO2 materials were tested as photocatalysts for the hydrogen evolution reaction (HER) from a water ethanol mixture and have shown uniquely high activity with the rate of H2 evolution achieving 11 mol h-1 per gram of Pt, which is the highest result for such materials reported to date. A combination of spectral methods shows that, under HER conditions, reduction of the supported PtOx species leads to the formation of well-dispersed nanoparticles of metallic platinum attached on the surface of TiO2 by Ti-O-Pt bonds. The high activity of the PtOx/TiO2 materials is believed to result from a combination of uniform distribution of small platinum nanoparticles over the titania surface and their close interaction with TiO2.

In this work, the extract of Nymphaea alba flowers was used as a reducing agent to synthesize platinum nanoparticles (Pt NPs), being such NPs characterized by different methods such as XRD, SEM and FT-IR. Crystal size of prepared Pt NPs was determined by SEM round circa 35 nm. Such characterized NPs were then applied to modify carbon paste electrodes (CPE/Pt NPs), which were electrochemically investigated by cyclic voltammetric method. The active surface area of CPE/Pt NPs was calculated about 0.027 cm2. Finally, the ability of this modified electrode was assessed to determine of hydrogen peroxide by amperometric technique. This modified electrode has shown a linear dynamic range of 1.5–250 μmol L−1 with detection limit of 0.7 μmol L−1. In addition, the electron transfer coefficient for hydrogen peroxide at the surface of CPE/Pt NPs was found to be 0.74. The simple preparation method, low costs (free enzyme), good stability, and efficient response are the advantages of this novel modified electrode as a sensor for determination of hydrogen peroxide.

In this report, polygonal angle platinum nanoparticles (PtNPs) anchored on nitrogen doping reduced graphene oxide (NrGO) as oxygen reduction reaction (ORR) catalyst was synthesized by gamma irradiation assisted with in situ hydrolysis of urea without using any shape inducer, seed, or template. Urea was not only employed as the nitrogen source, but also offered more reductive radicals in the gamma system. The uniform dispersion and homogeneous size distribution of PtNPs are obtained on reduced graphene oxide (rGO), which is attributed to the synergy of restriction effects of GO and crush capacity of high energy gamma rays. In addition, the method simultaneously offers PtNPs with polygonal angle structure and doping nitrogen in rGO, thus provides more surface and corner defects on PtNPs and heteroatomic defects on rGO, which synergistically improve the ORR performance of the samples. The obtained polygonal angle PtNPs modified NrGO exhibit fantabulous ORR activity in alkaline media with enhanced onset potential (906 mV), half-wave potential (783 mV) and superior limit current density (6.74 mA·cm−2) compared to the commercial Pt/C and those PtNPs supported on rGO composites. The results indicate that gamma irradiation assisted with in situ hydrolysis of urea can be a promising candidate method for preparation of high performance Pt-based catalysts in practical application.

Metal-organic framework (MOF)-related derivatives have generated significant interest in numerous energy conversion and storage applications, such as adsorption, catalysis, and batteries. However, such materials' real-world applicability is hindered because of scalability and reproducibility issues as they are produced by multistep postsynthesis modification of MOFs, often with high-temperature carbonization and/or calcination. In this process, MOFs act as self-sacrificial templates to develop functional materials at the expense of severe mass loss, and the resultant materials exhibit complex process-performance relationships. In this work, we report the direct applicability of a readily synthesized and commercially available MOF, a zeolitic imidazolate framework (ZIF-8), in a rechargeable zinc-air battery. The composite of cobalt-based ZIF-8 and platinum carbon black (ZIF-67@Pt/CB) prepared via facile solution mixing shows a promising bifunctional electrocatalytic activity for oxygen evolution reaction (OER) and oxygen reduction reaction (ORR), the key charge and discharge mechanisms in a battery. ZIF-67@Pt/CB exhibits long OER/ORR activity durability, notably, a significantly enhanced ORR stability compared to Pt/CB, 85 versus 52%. Interestingly, a ZIF-67@Pt/CB-based battery delivers high performance with a power density of >150 mW cm-2 and long stability for 100 h of charge-discharge cyclic test runs. Such remarkable activities from as-produced ZIF-67 are attributed to the electrochemically driven in situ development of an active cobalt-(oxy)hydroxide nanophase and interfacial interaction with platinum nanoparticles. This work shows commercial feasibility of zinc-air batteries as MOF-cathode materials can be reproducibly synthesized in mass scale and applied as produced.

This work describes a novel and portable pressure-based point-of-care (POC) testing strategy for the sensitive and rapid detection of carcinoembryonic antigen (CEA) via a flexible pressure sensor constructed by three-dimensional (3D) polypyrrole (PPy) foam. Initially, platinum nanoparticles (PtNPs) were conjugated to the detection antibodies, which were used to form sandwich-type immunocomplexes with targets and capture antibodies in the reaction cell. Then, the carried PtNPs catalyzed the dissociation of hydrogen peroxide (H2O2) for the generation of oxygen (O2) in a sealed device, translating the biomolecule recognition event into gas pressure. With the increase of pressure, a flexible pressure sensor with 3D polypyrrole foam as the sensing layer was used to sensitively monitor the pressure variations in this system. Thus, the concentration of the target could be quantitatively determined by the pressure response. Under optimal conditions, the pressure-based immunosensor showed good sensing performance for CEA in the dynamic working range from 0.2 to 60 ng/mL with a detection limit of 0.13 ng/mL. The reproducibility, specificity, and accuracy compared with commercial enzyme-linked immunosorbent assay (ELISA) kit were also acceptable. Therefore, this work provides a promising approach for developing portable and sensitive POC testing in the future.

Electrocatalyst supports stable to high potential are required for the proton exchange membrane fuel cell cathode. Electrocatalyst supports based on tantalum doped tin oxide (Ta: SnO2) were prepare...

Platinum ions and nanoparticles applications in the biomedical field include a number of pathologies. In particular, platinum ions are useful in the preparation of antitumoral drugs, whereas Pt nanoparticles (PtNPs) are known to reduce cellular oxidative stress. Herein, we developed composite materials using poly(ethylenimine) functionalized hydroxyapatite (HAPEI) as support for platinum. The presence of polyelectrolyte promotes interaction with platinum ion, which is loaded in greater amount than on pure hydroxyapatite. The dimensions of PtNPs are very small (about 1 nm), but increase up to about 20–30 nm on heat treatment. Loading Pt(II) ion on the apatitic supports provide a material with cytotoxic properties towards osteosarcoma derived cell lines (SaOS2 and MG63). On the contrary, PtNPs loaded apatitic supports display good anti-oxidant properties, in agreement with their quenching activity towards H2O2. Moreover, they promote differentiation of both primary osteoblast and osteoblast cell line, as shown by the increase of the levels of Alkaline Phosphatase and Collagen type 1, and reduce the level of reactive oxygen species with a consequent decrease of cellular oxidative stress.

Purpose Metal-based nanoparticles (M-NPs) have attracted great attention in nanomedicine due to their capacity to amplify and improve the tumor targeting of medical beams. However, their simple, efficient, high-yield and reproducible production remains a challenge. Currently, M-NPs are mainly synthesized by chemical methods or radiolysis using toxic reactants. The waste of time, loss of material and potential environmental hazards are major limitations. Materials and methods This work proposes a simple, fast and green strategy to synthesize small, non-toxic and stable NPs in water with a 100% production rate. Ionizing radiation is used to simultaneously synthesize and sterilize the containing NPs solutions. The synthesis of platinum nanoparticles (Pt NPs) coated with biocompatible poly(ethylene glycol) ligands (PEG) is presented as proof of concept. The physicochemical properties of NPs were studied by complementary specialized techniques. Their toxicity and radio-enhancing properties were evaluated in a cancerous in vitro model. Using plasmid nanoprobes, we investigated the elementary mechanisms underpinning radio-enhancement. Results and discussion Pt NPs showed nearly spherical-like shapes and an average hydrodynamic diameter of 9 nm. NPs are zero-valent platinum successfully coated with PEG. They were found non-toxic and have the singular property of amplifying cell killing induced by γ-rays (14%) and even more, the effects of carbon ions (44%) used in particle therapy. They induce nanosized-molecular damage, which is a major finding to potentially implement this protocol in treatment planning simulations. Conclusion This new eco-friendly, fast and simple proposed method opens a new era of engineering water-soluble biocompatible NPs and boosts the development of NP-aided radiation therapies.