Search Results (34)

The importance and challenges of ethylene detection based on combustion-type low-cost commercial sensors for agricultural and industrial applications are well-established. This work summarizes the significant progress in ethylene detection based on an innovative Gas Metal Oxide Semiconductor (GMOS) sensor and a new catalytic composition of metallic nanoparticles. The paper presents a study on ethylene and ethanol sensing using a miniature catalytic sensor fabricated by Complementary Metal Oxide Semiconductor–Silicon-on-Insulator–Micro-Electro-Mechanical System (CMOS-SOI-MEMS) technology. The GMOS performance with bimetallic palladium–platinum (Pd-Pt) and monometallic palladium (Pd) and platinum (Pt) catalysts is compared. The synergetic effect of the Pd-Pt catalyst is observed, which is expressed in the shift of combustion reaction ignition to lower catalyst temperatures as well as increased sensitivity compared to monometallic components. The optimal catalysts and their temperature regimes for low and high ethylene concentrations are chosen, resulting in lower power consumption by the sensor. Full article

In this study, mono- and bimetallic platinum (Pt), palladium (Pd) and Pt-Pd nanoparticles were synthesized using the wet sol–gel method, employing a carbon-based XC72R as catalytic carrier. The overall metal content was set at 40 wt.% at varying Pt:Pd ratios. Characterization of the morphology and surface structure was conducted through scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), Brunauer–Emmett–Teller (BET) and X-ray diffraction (XRD) analyses. The electrochemical performance and catalytic activity against the hydrogen evolution reaction (HER) were assessed in a three-electrode cell for screening purposes, as well as in a prototype cell of an electrochemical hydrogen pump/compressor (EHP/C) where the catalysts served as cathodes, while the anode was Pt/XC72 40% wt. with 0.38 mg_Pt·cm⁻² within a membrane electrode assembly (MEA) with a 180 µm thick Nafion 117 proton-conductive membrane. The results obtained indicated superior catalytic activity of the bimetallic catalysts in comparison to the pure metal samples. Further electrochemical tests in an EHP/C cell at varying differential pressures in the range of 0–3 bar revealed stable behavior and high current density, reaching approximately 0.7 A cm⁻² at 60 °C. The accelerated durability tests performed demonstrated excellent stability of the synthesized composite catalysts. These findings underscore the potential of Pt-Pd nanoparticles as efficient catalysts with sustainable performance for electrochemical hydrogen pumping/compressing applications. Full article

Declining natural resources make the recovery of metals from waste solutions a promising alternative. Moreover, processing waste into a finished product has its economic justification and benefits. Thus, the aim of this research was developing a Waste for Product strategy, indicating the possibility of processing solutions with a low content of platinum-group metals for catalyst synthesis. The results obtained confirmed that diluted synthetic waste solutions containing trace amount of valuable metal ions (Pd, Pt) can be used for the process of catalyst synthesis. Catalysts produced in the form of palladium and platinum nanoparticles were successfully deposited on a Ni foam due to the galvanic displacement mechanism. Synthesized catalysts were characterized using UV-Vis spectrophotometry, SEM/EDS, and XRD techniques. Electro- and catalytic properties were tested for hydrogen/oxygen evolution reactions and methyl orange degradation, respectively. The results obtained from electrocatalytic tests indicated that the modification of the nickel foam surface by waste solutions consisting of noble metals ions as Pd and Pt can significantly increase the activity in hydrogen and oxygen evolution reactions in comparison to non-treated samples. Catalytic tests performed for the process of methyl orange degradation shorten the time of the process from several hours to 15 min. The most favorable results were obtained for the catalysts in the following order Pd1.0Pt0@Ni > Pd0Pt1.0@Ni > Pd0.5Pt0.5@Ni > Ni foam > no catalyst, indicating the best catalytic performance for catalyst containing pure palladium nanoparticles deposited on the nickel surface. Full article

Platinum (Pt) and palladium (Pd) are crucial in hydrogen energy technologies, especially in fuel cells, due to their high catalytic activity and chemical stability. Pt-Pd nanoparticles, produced through various methods, enhance catalytic performance based on their size, shape, and composition. These nanocatalysts excel in direct methanol fuel cells (DMFCs) and direct ethanol fuel cells (DEFCs) by promoting alcohol oxidation and reducing CO poisoning. Pt-Pd catalysts are also being explored for their oxygen reduction reaction (ORR) on the cathodic side of fuel cells, showing higher activity and stability than pure platinum. Molecular dynamics (MD) simulations have been conducted to understand the structural and surface energy effects of PdPt nanoparticles, revealing phase separation and chemical ordering, which are critical for optimizing these catalysts. Pd migration to the surface layer in Pt-Pd alloys minimizes the overall potential energy through the formation of Pd surface monolayers and Pt-Pd bonds, leading to a lower surface energy for intermediate compositions compared to that of the pure elements. The potential energy, calculated from MD simulations, increases with a decreasing particle size due to surface creation, indicating higher reactivity for smaller particles. A general contraction of the average distance to the nearest neighbour atoms was determined for the top surface layers within the nanoparticles. This research highlights the significant impact of Pd segregation on the structural and surface energy properties of Pt-Pd nanoparticles. The formation of Pd monolayers and the resulting core–shell structures influence the catalytic activity and stability of these nanoparticles, with smaller particles exhibiting higher surface energy and reactivity. These findings provide insights into the design and optimization of Pt-Pd nanocatalysts for various applications. Full article

The presented research is the seed of a vision for the development of a waste-for-product strategy. Following this concept, various synthetic solutions containing low concentrations of platinum group metals were used to model their recovery and to produce catalysts. This is also the first report that shows the method for synthesis of a pyramid-like structure deposited on activated carbon composed of Pd and Pt. This unique structure was obtained from a mixture of highly diluted aqueous solutions containing both metals and chloride ions. The presence of functional groups on the carbon surface and experimental conditions allowed for: the adsorption of metal complexes, their reduction to metal atoms and enabled further hierarchical growth of the metal layer on the carbon surface. During experiments, spherical palladium and platinum nanoparticles were obtained. The addition of chloride ions to the solution promoted the hierarchical growth and formation of palladium nanopyramids, which were enriched with platinum nanoparticles. The obtained materials were characterized using UV–Vis, Raman, IR spectroscopy, TGA, SEM/EDS, and XRD techniques. Moreover, Pd@ROY, Pt@ROY, and Pd-Pt@ROY were tested as possible electrocatalysts for hydrogen evolution reactions. Full article

PAPLAL, a mixture of platinum (nPt) and palladium (nPd) nanoparticles, is widely used as a topical agent because of its strong antioxidant activity. Allergic contact dermatitis (ACD) is one of the most common occupational skin diseases worldwide. However, the role of oxidative stress in ACD remains unclear. In the present study, we investigated the protective effects of topical PAPLAL treatment on 2,4-dinitrofluorobenzene (DNFB)-induced ACD. DNFB treatment increased 8-isoprostane content; upregulated Xdh, Nox2, and Nox4, pro-oxidant genes; and downregulated Sod1, an antioxidant gene, indicating oxidative damage in the ear skin. PAPLAL therapy significantly reduced ear thickness associated with the downregulation of inflammatory cytokine-related genes. PAPLAL also significantly increased the expression of the stress-response-related genes Ahr and Nrf2, as well as their target genes, but failed to alter the expression of redox-related genes. Furthermore, Sod1 loss worsened ACD pathologies in the ear. These results strongly suggest that PAPLAL protects against ACD through its antioxidant activity and activation of the AHR and NRF2 axes. The antioxidant PAPLAL can be used as a novel topical therapy for ACD that targets oxidative stress. Full article

In this study, we investigated the catalytic properties of mono- and bimetallic palladium (Pd) and platinum (Pt) nanoparticles deposited via supercritical fluid reactive deposition (SFRD) on titanium dioxide (TiO₂) powder. Transmission electron microscopy analyses verified that SFRD experiments performed at 353 K and 15.6 MPa enabled the deposition of uniform mono- and bimetallic nanoparticles smaller than 3 nm on TiO₂. Electron-dispersive X-ray spectroscopy demonstrated the formation of alloy-type structures for the bimetallic PdPt nanoparticles. H₂O₂ is an excellent oxidizing reagent for the production of fine and bulk chemicals. However, until today, the design and preparation of catalysts with high H₂O₂ selectivity and productivity remain a great challenge. The focus of this study was on answering the questions of (a) whether the catalysts produced are suitable for the direct synthesis of hydrogen peroxide (H₂O₂) in the liquid phase and (b) how the metal type affects the catalytic properties. It was found that the metal type (Pd or Pt) influenced the catalytic performance strongly; the mean productivity of the mono- and bimetallic catalysts decreased in the following order: Pd > PdPt > Pt. Furthermore, all catalysts prepared by SFRD showed a significantly higher mean productivity compared to the catalyst prepared by incipient wetness impregnation. Full article

The exploration into nanomaterial-based nonenzymatic biosensors with superb performance in terms of good sensitivity and anti-interference ability in disease marker monitoring has always attained undoubted priority in sensing systems. In this work, we report the design and synthesis of a highly active nanocatalyst, i.e., palladium and platinum nanoparticles (Pt&Pd-NPs) decorated ultrathin nanoporous gold (NPG) film, which is modified on a homemade graphene paper (GP) to develop a high-performance freestanding and flexible nanohybrid electrode. Owing to the structural characteristics the robust GP electrode substrate, and high electrochemically catalytic activities and durability of the permeable NPG support and ultrafine and high-density Pt&Pd-NPs on it, the resultant Pt&Pd-NPs–NPG/GP electrode exhibits excellent sensing performance of low detection limitation, high sensitivity and anti-interference capability, good reproducibility and long-term stability for the detection of small molecular biomarkers hydrogen peroxide (H₂O₂) and glucose (Glu), and has been applied to the monitoring of H₂O₂ in different types of live cells and Glu in body fluids such as urine and fingertip blood, which is of great significance for the clinical diagnosis and prognosis in point-of-care testing. Full article

The search for alternatives to cisplatin has led to the development of new metal complexes where thiazoline derivatives based on platinum(II) and palladium(II) stand out. In this sense, the Pt(II) and Pd(II) complexes coordinated with the thiazoline derivative ligand 2-(3,4-dichlorophenyl)imino-N-(2-thiazolin-2-yl)thiazolidine (TdTn), with formula [PtCl₂(TdTn)] and [PdCl₂(TdTn)], have previously shown good results against several cancer lines; however, in this work, we have managed to improve their activity by supporting them on mesoporous silica nanoparticles (MSN). The incorporation of metal compounds with a melatonin derivative (5-methoxytryptamine, 5MT), which is a well-known antioxidant and apoptosis inducer in different types of cancer, has been able to increase the cytotoxic activity of both MSN-supported and isolated complexes with only a very low amount (0.35% w/w) of this antioxidant. The covalently functionalized systems that have been synthesized are able to increase selectivity as well as accumulation in HeLa cells. The final materials containing the metal complexes and 5MT (MSN-5MT-PtTdTn and MSN-5MT-PdTdTn) required up to nine times less metal to achieve the same cytotoxic activity than their corresponding non-formulated counterparts did, thus reducing the potential side effects caused by the use of the free metal complexes. Full article

We demonstrate a simple, low-energy method whereby tomato mosaic virus (ToMV) particles can be used to template the production of nanowires and particles consisting of alloys of gold (Au), platinum (Pt) and palladium (Pd) in various combinations. Selective nanowire growth within the inner channel of the particles was achieved using the polymeric capping agent polyvinylpyrrolidone (PVP_K30) and the reducing agent ascorbic acid. The reaction conditions also resulted in the deposition of alloy nanoparticles on the external surface of the rods in addition to the nanowire structures within the internal cavity. The resulting materials were characterized using a variety of electron microscopic and spectroscopic techniques, which revealed both the structural and chemical composition of the alloys within the nanomaterials. Full article

With the unprecedented development of green and renewable energy sources, the proportion of clean hydrogen (H₂) applications grows rapidly. Since H₂ has physicochemical properties of being highly permeable and combustible, high-performance H₂ sensors to detect and monitor hydrogen concentration are essential. This review discusses a variety of fiber-optic-based H₂ sensor technologies since the year 1984, including: interferometer technology, fiber grating technology, surface plasma resonance (SPR) technology, micro lens technology, evanescent field technology, integrated optical waveguide technology, direct transmission/reflection detection technology, etc. These technologies have been evolving from simply pursuing high sensitivity and low detection limits (LDL) to focusing on multiple performance parameters to match various application demands, such as: high temperature resistance, fast response speed, fast recovery speed, large concentration range, low cross sensitivity, excellent long-term stability, etc. On the basis of palladium (Pd)-sensitive material, alloy metals, catalysts, or nanoparticles are proposed to improve the performance of fiber-optic-based H₂ sensors, including gold (Au), silver (Ag), platinum (Pt), zinc oxide (ZnO), titanium oxide (TiO₂), tungsten oxide (WO₃), Mg₇₀Ti₃₀, polydimethylsiloxane (PDMS), graphene oxide (GO), etc. Various microstructure processes of the side and end of optical fiber H₂ sensors are also discussed in this review. Full article

Many diseases in the human body are related to the level of L-cysteine. Therefore, it is crucial to establish an efficient, simple and sensitive platform for L-cysteine detection. In this work, we synthesized platinum palladium bimetallic nanoparticles (Van-Pt_m/Pd_n NPs) using vancomycin hydrochloride (Van) as a stabilizer, which exhibited high oxidase-like catalytic activity. In addition, the catalytic kinetics of the Van-Pt₁/Pd₁ NPs followed the typical Michaelis–Menten equation, exhibiting a strong affinity for 3,3′,5,5′-tetramethylbenzidine substrates. More importantly, we developed a simple and effective strategy for the sensitive colorimetric detection of L-cysteine using biocompatible Van-Pt₁/Pd₁ NPs. The detection limit was low, at 0.07 μM, which was lower than the values for many previously reported enzyme-like detection systems. The colorimetric method of the L-cysteine assay had good selectivity. The established method for the detection of L-cysteine showed promise for biomedical analysis. Full article

Up till now, there have been extremely contradictory opinions and inadequate results concerning surface segregation in binary platinum–palladium (Pt–Pd) nanoparticles, including the problems regarding segregating components, as well as the size and temperature dependences of segregation. Taking into account such a situation, we investigated the surface segregation in Pt–Pd nanoparticles by combining atomistic (molecular dynamics) and thermodynamic simulations. For molecular dynamics experiments, the well-known program LAMMPS and the embedded atom method were employed. In the course of the atomistic simulations, two different sets of parameterizations for the Pt–Pt, Pd–Pd, and Pt–Pd interatomic interaction potentials were used. The thermodynamic simulation was based on solving the Butler equation by employing several successive approximations. The results obtained via atomistic simulation and thermodynamic simulation on the basis of the Butler equation were compared with each other, as well as with predictions that were based on the Langmuir–McLean equation and some experimental data. Both simulation methods (atomistic and thermodynamic) predicted the surface segregation of Pd, which diminishes with the nanoparticle size and with increasing temperature. Our simulation results do not confirm the predictions of some authors on surface segregation inversion, i.e., the reversal from the surface segregation of Pd to the surface segregation of Pt when diminishing the nanoparticle size. Full article

Surface plasmon resonance (SPR) photocatalysts have attracted considerable attention because of their strong absorption capacity of visible light and enhanced photogenic carrier separation efficiency. However, the separate production of metal nanoparticles (NPs) and semiconductors limits the photogenic charge transfer. As one of the most promising organic photocatalysts, porphyrin self-assemblies with a long-range ordered structure-enhance electron transfer. In this study, plasmonic noble metal-based porphyrin hexagonal submicrowires composites (M-HW) loaded with platinum (Pt), silver (Ag), gold (Au), and palladium (Pd) NPs were synthesized through a simple in situ photocatalytic method. Homogeneous and uniformly distributed metal particles on the M-HW composites enhanced the catalytic or chemical properties of the organic functional nanostructures. Under the same loading of metal NPs, the methyl orange photocatalytic degradation efficiency of Ag-HW [k_Ag-HW (0.043 min⁻¹)] composite was three times higher than that of HW, followed by Pt-HW [k_Pt-HW (0.0417 min⁻¹)], Au-HW [k_Au-HW (0.0312 min⁻¹)], and Pd-HW [k_Pd-HW (0.0198 min⁻¹)]. However, the rhodamine B (RhB) and eosin B photocatalytic degradations of Pt-HW were 4 times and 2.6 times those of HW, respectively. Finally, the SPR-induced electron injection, trapping, and recombination processes of the M-HW system were investigated. These results showed that M-HW plasmonic photocatalysts exhibited excellent photocatalytic performances, making them promising materials for photodegrading organic pollutants. Full article

Eliminating clogging in capillary tube reactors is critical but challenging for enabling continuous-flow microfluidic synthesis of nanoparticles. Creating immiscible segments in a microfluidic flow is a promising approach to maintaining a continuous flow in the microfluidic channel because the segments with low surface energy do not adsorb onto the internal wall of the microchannel. Herein we report the spontaneous self-agglomeration of reduced graphene oxide (rGO) nanosheets in polyol flow, which arises because the reduction of graphene oxide (GO) nanosheets by hot polyol changes the nanosheets from hydrophilic to hydrophobic. The agglomerated rGO nanosheets form immiscible solid segments in the polyol flow, realizing the liquid–solid segmented flow to enable clogging aversion in continuous-flow microfluidic synthesis. Simultaneous reduction of precursor species in hot polyol deposits nanocrystals uniformly dispersed on the rGO nanosheets even without surfactant. Cuprous oxide (Cu₂O) nanocubes of varying edge lengths and ultrafine metal nanoparticles of platinum (Pt) and palladium (Pd) dispersed on rGO nanosheets have been continuously synthesized using the liquid–solid segmented flow microfluidic method, shedding light on the promise of microfluidic reactors in synthesizing functional nanomaterials. Full article