Facile Fabrication of Platinum-Cobalt Alloy Nanoparticles with Enhanced Electrocatalytic Activity for a Methanol Oxidation Reaction

Synthesis of platinum nanoparticles functionalized with glutamine and conjugated with thiosemicarbazone and their cytotoxic effects on MDA-MB-231 breast cancer cell line and evaluation of CASP-8 gene expression

Breast cancer (BC) is the most prevalent form of cancer among women and is a major contributor to cancer-related fatalities. Nanotechnology has provided novel approaches to drug delivery to cancer cells. In this work, we synthesized platinum (Pt) nanoparticles, functionalized them with glutamine, conjugated them with thiosemicarbazone (TSC), and characterized their anticancer effects on the MDA-MB-231 breast cancer cell line. Characteristics of the nanoparticles were assessed by FT-IR, XRD, EDS mapping, SEM, TEM, DLS, and zeta potential measurement. Cell viability was characterized by MTT assay, and cell necrosis/apoptosis levels were determined by flow cytometry. The expression level of the CASP-8 gene was investigated by real-time PCR. Pt@Gln-TSC nanoparticles are spherical, 20-70 nm in diameter in dry form, 662 nm after hydration, and their zeta potential was - 6.6 mV. The 50% inhibitory concentration (IC50) for MDA-MB-231 (breast cancer) and HDF (normal) cell lines was 170 and 348µg/ml, respectively. Also, the IC50 of oxaliplatin drug and TSC on MDA-MB-231 cells was 184 µg/ml and 307 µg/ml, respectively. Treatment with Pt@Gln-TSC nanoparticles caused an increase in cell necrosis and primary apoptosis and elevated the expression of the CASP-8 gene by 2.54 folds. This study shows that Pt@Gln-TSC nanoparticles are significantly more toxic to breast cancer cells than to normal cells and can inhibit MDA-MB-231 cells by activating extrinsic apoptosis.

Environmentally friendly PtNiCo nanocatalysts enhanced with multi-walled carbon nanotubes for sustainable methanol oxidation in an alkaline medium

In this study, trimetallic PtNiCo/MWCNT and PtNiCo catalysts were synthesized using a microwave method to reduce the amount of precious Pt. The prepared catalysts were characterized using XRD, TEM, and EDX mapping and their electrochemical performances for methanol oxidation were investigated. The results showed that the MWCNT-supported catalyst showed 2.42 times higher electrochemical activity than the PtNiCo catalyst with a peak current density of 283.14 mA cm-2 at -0.2 V potential. Moreover, in long-term stability tests, it exhibited high stability and 4.97 times higher current density at the end of 3600 s. The results showed that the MWCNT-supported catalyst offered improved electron transfer, 4.7 times higher surface area, and resistance to CO poisoning. These performance improvements due to the trimetallic structure are mostly thought to help accelerate the dehydrogenation of methanol. This study contains important findings for future functional catalyst design in the fields of catalysis and energy conversion.

Self-Optimized Ligand Effect of Single-Atom Modifier in Ternary Pt-Based Alloy for Efficient Hydrogen Oxidation

Modifying the atomic and electronic structure of platinum-based alloy to enhance its activity and anti-CO poisoning ability is a vital issue in hydrogen oxidation reaction (HOR). However, the role of foreign modifier metal and the underlying ligand effect is not fully understood. Here, we propose that the ligand effect of single-atom Cu can dynamically modulate the d-band center of Pt-based alloy for boosting HOR performance. By in situ X-ray absorption spectroscopy, our research has identified that the potential-driven structural rearrangement into high-coordination Cu-Pt/Pd intensifies the ligand effect in Pt-Cu-Pd, leading to enhanced HOR performance. Thereby, modulating the d-band structure leads to near-optimal hydrogen/hydroxyl binding energies and reduced CO adsorption energies for promoting the HOR kinetics and the CO-tolerant capability. Accordingly, PtPdCu₁/C exhibits excellent CO tolerance even at 1,000 ppm impurity.

Effect of the Preparation Conditions on the Catalytic Properties of CoPt for Highly Efficient 4-Nitrophenol Reduction

CoPt alloys with Pt contents from 15 to 90% were prepared using low-cost electrochemical deposition. Different samples were synthesized from electrochemical baths at pH = 2.5 and 5.5 in a solution with and without saccharin as an additive. The morphology, composition and crystalline structure of the as-prepared samples were investigated by High Resolution-Scanning Electron Microscopy (HR-SEM), Atomic Force Microscopy (AFM), Ultra-high Resolution-Transmission Electron Microscopy (UHR-TEM), Energy-Dispersive X-ray Spectroscopy (EDX), and X-ray Diffraction (XRD). XRD investigations revealed that fcc crystalline structure transforms into hcp crystalline structure when the pH of the electrochemical bath is increased from 2.5 to 5.5 as well as when saccharin is added to the electrochemical bath. The catalytic performance of the CoPt alloys for the nitro to amino phenol compounds conversion was investigated for all the prepared samples, and the results show that the conversion degree increases (from 11.4 to 96.5%) even though the Pt content in the samples decreases. From the samples prepared from the electrochemical bath with saccharin, a study regarding the effect of contact time was performed. The results indicated that after only 5 min, the CoPt sample prepared at pH = 5.5 in the presence of saccharin completely converted the nitro compound to an amino compound.

Highly Efficient ZIF-67-Derived PtCo Alloy-CN Interface for Low-Temperature Aqueous-Phase Fischer-Tropsch Synthesis

Designing new materials for selective Fischer-Tropsch synthesis (FTS) is an elegant way to enhance local feedstock utilization like biomass and waste. In this approach, we have designed a thermally and chemically stable bimetallic PtCo/NC hybrid nanocomposite catalyst derived from a zeolitic imidazolate framework (ZIF-67, which contains cobalt as a metal center) through carbonization for low-temperature (413-473 K) aqueous-phase Fischer-Tropsch synthesis (AFTS). The selectivity of the desired range of hydrocarbons is adjusted using a highly dispersed PtCo bimetallic alloy, which facilitates extraordinary reduction of a metal oxide to active species by the synergic effect under the AFTS reaction conditions. The ZIF-derived catalyst tested in this study exhibited the highest activity to date for very low temperatures (433 K) in aqueous-phase Fischer-Tropsch synthesis with CO conversion rates between 0.61 and 1.20 mol_CO·mol_Co^-1·h^-1. Insights of the remarkable catalyst activity were examined by in situ X-ray photoelectron spectroscopy (XPS) studies corroborated by density functional theory (DFT) calculation. The bimetallic Co₃Pt (111) surface was found to be highly active for the C-C coupling reaction between surface-adsorbed C and CO, forming a CCO intermediate with a very low activation barrier (E_a = 0.37 eV), in comparison to the C-C coupling activation barrier obtained over the Co (111) surface (E_a = 0.87 eV). This unique approach and observations create a new path for developing next-generation advanced catalyst systems and processes for selective low-temperature FTS.

Pt@Metal-Organic Framework (ZIF-8) Thin Films Obtained at a Liquid/Liquid Interface as Anode Electrocatalysts for Methanol Fuel Cells: Different Approaches in the Synthesis

Smart membranes, nanodevices, chemical sensors, and catalytic coatings are some of the applications that make the metal-organic framework (MOF) thin films very important. Encapsulation of nanoparticles in the porous structure of MOFs can lead to the formation of effective catalysts with new unique properties and wide range of applications that may not be obtained by MOFs individually. Three main strategies, ship-in-a-bottle, bottle-around-the-ship, and in situ synthesis including the simultaneous formation of the two components, were applied for the synthesis of Pt(0)@zeolitic imidazolate framework-8 (ZIF-8) thin films at the toluene/water interface. The effects of platinum precursor transfer directions toward the interface on the properties of the films were investigated by using the [PtCl₂(cod)] (where cod = cis,cis-1,5-cyclooctadiene) complex soluble in toluene as the upper phase and K₂PtCl₄ soluble in water as the lower phase. The six obtained films with different morphologies were applied as electrocatalysts for the methanol oxidation reaction. Considerable current density, mass activity, catalyst stability, activation energy, exchange current density, maximum power, and long-term poisoning rate are some of the advantages of the Pt(0)@ZIF-8 catalysts synthesized using the in situ strategy and K₂PtCl₄ as the platinum precursor. Furthermore, we report the formation of Pt@ZIF-8 nanorods at the interfaces without using any stabilizer or template. Our results suggest that the in situ strategy at the liquid/liquid interface is one of the best procedures for the synthesis of Pt(0)@ZIF-8 thin films as a suitable anode electrocatalyst for methanol fuel cells.

Surfactant-Free Monodispersed Pd Nanoparticles Template for Core-Shell Pd@PdPt Nanoparticles as Electrocatalyst towards Methanol Oxidation Reaction (MOR)

An eco-friendly two-step synthetic method for synthesizing Pd@PdPt/CNTs nanoparticles was introduced and studied for the methanol oxidation reaction. The Pd@PdPt alloy core-shell structure was synthesized by preparing a surfactant-free monodispersed Pd/CNTs precursor through the hydrolysis of tetrachloropalladate (II) ion ([PdCl₄]²⁻) in the presence of carbon nanotubes (CNTs) and the subsequent hydrogen reduction and followed by a galvanic replacement reaction. This method opens up an eco-friendly, practical, and straightforward route for synthesizing monometallic or bimetallic nanoparticles with a clean surfactant-free electrocatalytic surface. It is quite promising for large-scale preparation. The Pd@PdPt/CNTs electrocatalyst demonstrated a high specific mass activity for methanol oxidation (400.2 mAmg_Pt⁻¹) and excellent stability towards direct methanol oxidation compared to its monometallic counterparts.

Polyquaternium enhances the colloidal stability of chitosan-capped platinum nanoparticles and their antibacterial activity

Here, for the first time, we have developed a novel green synthesis method where chitosan acts as a reducing agent and as a colloidal stabilizer, together with polyquaternium for the synthesis of platinum nanoparticles (PtNPs). It was observed that only chitosan-stabilized PtNPs (Ch@PtNPs) were stable up to pH 5, with a diameter of around 89 nm. The diameter of the Ch@PtNPs increased with the increase in pH, indicating the instability of Ch@PtNPs at neutral and alkaline mediums. However, when polyquaternium (PQ) (a cationic polymer) was added as a stabilizer along with chitosan, the diameter of chitosan/polyquaternium stabilized PtNPs (Ch/PQ@PtNPs), i.e. 87 nm, remained almost constant up to pH 9. Similarly, the pH-dependent decrease in the surface charge of Ch@PtNPs was also attenuated with the addition of polyquaternium. This indicates high colloidal stability of Ch/PQ@PtNPs in acidic, neutral, as well as alkaline mediums. It was observed that Ch/PQ@PtNPs exhibited high antibacterial activity againstStaphylococcus aureus, as compared to uncapped PtNPs and Ch@PtNPs. Thus, the addition of PQ increases the antibacterial properties of Ch/PQ@PtNPs againstStaphylococcus aureusby enhancing the stability of PtNPs at neutral pH.

DNA-Modified Cobalt Tungsten Oxide Hydroxide Hydrate Nanochains as an Effective Electrocatalyst with Amplified CO Tolerance during Methanol Oxidation

Direct methanol fuel cell technology implementation mainly depends on the development of non-platinum catalysts with good CO tolerance. Among the widely studied transition-metal catalysts, cobalt oxide with distinctively higher catalytic efficiency is highly desirable. Here, we have evolved a simple method of synthesizing cobalt tungsten oxide hydroxide hydrate nanowires with DNA (CTOOH/DNA) and without incorporating DNA (CTOOH) by microwave irradiation and subsequently employed them as electrocatalysts for methanol oxidation. Following this, we examined the influence of incorporating DNA into CTOOH by cyclic voltammetry, chronoamperometry, and electrochemical impedance spectroscopy. The enhanced electrochemical surface area of CTOOH offered readily available electroactive sites and resulted in a higher oxidation current at a lower onset potential for methanol oxidation. On the other hand, CTOOH/DNA exhibited improved CO tolerance and it was evident from the chronoamperometric studies. Herein, we noticed only a 2.5 and 1.8% drop at CTOOH- and CTOOH/DNA-modified electrodes, respectively, after 30 min. Overall, from the results, it was evident that the presence of DNA in CTOOH played an important role in the rapid removal of adsorbed intermediates and regenerated active catalyst centers possibly by creating high density surface defects around the nanochains than bare CTOOH.

A Robust PtNi Nanoframe/N-Doped Graphene Aerogel Electrocatalyst with Both High Activity and Stability

Insufficient catalytic activity and stability and high cost are the barriers for Pt-based electrocatalysts in wide practical applications. Herein, a hierarchically porous PtNi nanoframe/N-doped graphene aerogel (PtNiNF-NGA) electrocatalyst with outstanding performance toward methanol oxidation reaction (MOR) in acid electrolyte has been developed via facile tert-butanol-assisted structure reconfiguration. The ensemble of high-alloying-degree-modulated electronic structure and correspondingly the optimum MOR reaction pathway, the structure superiorities of hierarchical porosity, thin edges, Pt-rich corners, and the anchoring effect of the NGA, endow the PtNiNF-NGA with both prominent electrocatalytic activity and stability. The mass and specific activity (1647 mA mg_Pt ^-1 , 3.8 mA cm^-2 ) of the PtNiNF-NGA are 5.8 and 7.8 times higher than those of commercial Pt/C. It exhibits exceptional stability under a 5-hour chronoamperometry test and 2200-cycle cyclic voltammetry scanning.

Pt-Co3O4 Superstructures by One-Pot Reduction/Precipitation in Bicontinuous Microemulsion for Electrocatalytic Oxygen Evolution Reaction

Bicontinuous microemulsions (BCME) were used to synthesize hierarchical superstructures (HSs) of Pt-Co3O4 by reduction/precipitation. BCMEs possess water and oil nanochannels, and therefore, both hydrophilic and lipophilic precursors can be used. Thus, PtAq-CoAq, PtAq-CoOi, PtOi-CoAq and PtOi-CoOi were prepared (where Aq and Oi stand for the precursor present in aqueous or oily phase, respectively). The characterization of the Pt-Co3O4-HS confirmed the formation of metallic Pt and Co3O4 whose composition and morphology are controlled by the initial pH and precursor combination, determining the presence of the reducing/precipitant species in the reaction media. The electrocatalytic activity of the Pt-Co3O4-HSs for oxygen evolution reaction (OER) was investigated using linear sweep voltammetry in 0.1 M KOH and compared with Pt-HS. The lowest onset overpotentials for Pt-Co3O4-Hs were achieved with PtOi-CoOi (1.46 V vs. RHE), while the lowest overpotential at a current density of 10 mA cm−2 (η10) was obtained for the PtAq-CoAq (381 mV). Tafel slopes were 102, 89, 157 and 92 mV dec−1, for PtAq-CoAq, PtAq-CoOi, PtOi-CoAq and PtOi-CoOi, respectively. The Pt-Co3O4-HSs showed a better performance than Pt-HS. Our work shows that the properties and performance of metal–metal oxide HSs obtained in BCMEs depend on the phases in which the precursors are present.

Enhanced H2 production from dehydrogenation of sodium borohydride over the ternary Co0.97Pt0.03/CeO x nanocomposite grown on CGO catalytic support

The development of low-cost materials for the 100% dehydrogenation of metal hydrides is highly essential to vitalize the chemical hydride-based hydrogen economy. In this context, the ternary Co-Ce-Pt nanocomposite immobilized on functionalized catalytic support CGO is synthesized by the one step chemical reduction approach and has been directly employed for the ethanolysis of sodium borohydride. The co-operative effect of CGO and the synergy between metallic nanoparticles is investigated to determine the highest rate of hydrogen (H2) production. The maximum hydrogen generation rate (HGR) of 41.53 L (min g M )-1 is achieved with the Co0.97Pt0.03/CeO x /CGO nanohybrid from the alkaline ethanolysis of sodium borohydride (SB). In addition, the resultant nanohybrid exhibited a relatively low activation energy of 21.42 kJ mol-1 for the ethanolysis of SB. This enhanced catalytic activity may be attributed to the intermetallic charge transport among metallic Pt, Co/Co3O4, and CeO x counterparts. Moreover, the catalytic support CGO provides mesoporous functionalized surface and its intercalated GO layers promote charge transport. These results indicate that the resultant catalytic system described here for the dehydrogenation of SB can offer a portable and low-cost H2 supply for various fuel cell applications.

Effect of Metal Substrate on Electrocatalytic Property of Palladium Nanowire Array for High Performance Ethanol Electro-Oxidation

In this research, a high performance, ionomer-free electrocatalyst based on vertically aligned palladium (Pd) nanowire array was developed as an anode electrode toward ethanol oxidation reaction (EOR) in an alkaline environment. Using a one-step electrodeposition method, the Pd nanowires with controlled length were obtained by varying the electrodeposition current density and the synthesis time. Scanning electron microcopy (SEM), energy dispersive X-ray spectroscopy (EDS), and X-ray powder diffraction (XRD) were employed to characterize the morphology, chemical composition, and crystal structure of the Pd nanowires. The length effects of the nanowires, in the range of 0.8-4.5 μm, and various metal substrates, such as Ag, Cu, Ni, and Ti, were investigated for their electrochemical activities. The results demonstrated that Ag was the most active substrate to facilitate the ethanol oxidation reaction of the Pd nanowire array (NWA) electrocatalyst, which could be related to its good electrical conductivity. The stability test of the Pd NWA/Ag over time for EOR was also carried out, and the catalytic activity was recovered after the electrode was replaced with a new ethanol solution. Electrochemical impedance spectroscopy (EIS) measurements were performed to provide insights in the electron transfer resistance between the electrode and analyte. Gas chromatography and UV-vis spectroscopy were employed to measure the concentration of chemical species, which helped elucidate the overall reaction mechanism on the electrode surfaces.

Synthesis of Hollow Pt-Ni Nanoboxes for Highly Efficient Methanol Oxidation

In direct methanol fuel cell technology, highly stable electrochemical catalysts are critically important for their practical utilization at the commercial scale. In this study, sub ~10 nm hollow Pt-Ni (1:1 at. ratio) nanoboxes supported on functionalized Vulcan carbon (Pt-Ni/C-R2) were synthesized through a facile method for the efficient electrooxidation of methanol. Two reaction procedures, namely, a simultaneous reduction and a modified sequential reduction method using a reverse microemulsion (RME) method, were adopted to synthesize solid Pt-Ni NPs and hollow nanoboxes, respectively. To correlate the alloy composition and surface structure with the enhanced catalytic activity, the results were compared with the nanocatalyst synthesized using a conventional NaBH₄ reduction method. The calculated electroactive surface area for the Pt-Ni/C-R2 nanoboxes was 190.8 m².g^-1, which is significantly higher compared to that of the Pt-Ni nanocatalyst (96.4 m².g^-1) synthesized by a conventional reduction method. Hollow nanoboxes showed 34% and 44% increases in mass activity and rate of methanol oxidation reaction, respectively, compared to solid NPs. These results support the nanoreactor confinement effect of the hollow nanoboxes. The experimental results were supported by Density Functional Theory (DFT) studies, which revealed that the lowest CO poisoning of the Pt₁Ni₁ catalyst among all Pt_m-Ni_n mixing ratios may account for the enhanced methanol oxidation. The synthesized hollow Pt-Ni/C (R2) nanoboxes may prove to be a valuable and highly efficient catalysts for the electrochemical oxidation of methanol due to their low cost, numerous catalytically active sites, low carbon monoxide poisoning, large electroactive surface area and long-term stability.

Wire-like Pt on mesoporous Ti0.7W0.3O2 Nanomaterial with Compelling Electro-Activity for Effective Alcohol Electro-Oxidation

Finding out robust active and sustainable catalyst towards alcohol electro-oxidation reaction is major challenges for large-scale commercialization of direct alcohol fuel cells. Herein, a robust Pt nanowires (NWs)/Ti_0.7W_0.3O₂ electrocatalyst, as the coherency of using non-carbon catalyst support and controlling the morphology and structure of the Pt nanocatalyst, was fabricated via an effortless chemical reduction reaction approach at room temperature without using surfactant/stabilizers or template to assemble an anodic electrocatalyst towards methanol electro-oxidation reaction (MOR) and ethanol electro-oxidation reaction (EOR). These observational results demonstrated that the Pt NWs/Ti_0.7W_0.3O₂ electrocatalyst is an intriguing anodic electrocatalyst, which can alter the state-of-the-art Pt NPs/C catalyst. Compared with the conventional Pt NPs/C electrocatalyst, the Pt NWs/Ti_0.7W_0.3O₂ electrocatalyst exhibited the lower onset potential (~0.1 V for MOR and ~0.2 for EOR), higher mass activity (~355.29 mA/mg_Pt for MOR and ~325.01 mA/mg_Pt for EOR) and much greater durability. The outperformance of the Pt NWs/Ti_0.7W_0.3O₂ electrocatalyst is ascribable to the merits of the anisotropic one-dimensional Pt nanostructure and the mesoporous Ti_0.7W_0.3O₂ support along with the synergistic effects between the Ti_0.7W_0.3O₂ support and the Pt nanocatalyst. Furthermore, this approach may provide a promising catalytic platform for fuel cell technology and a variety of applications.

A Review on the Promising Plasma-Assisted Preparation of Electrocatalysts

Electrocatalysts are becoming increasingly important for both energy conversion and environmental catalysis. Plasma technology can realize surface etching and heteroatom doping, and generate highly dispersed components and redox species to increase the exposure of the active edge sites so as to improve the surface utilization and catalytic activity. This review summarizes the recent plasma-assisted preparation methods of noble metal catalysts, non-noble metal catalysts, non-metal catalysts, and other electrochemical catalysts, with emphasis on the characteristics of plasma-assisted methods. The influence of the morphology, structure, defect, dopant, and other factors on the catalytic performance of electrocatalysts is discussed.

Oxidatively induced exposure of active surface area during microwave assisted formation of Pt3Co nanoparticles for oxygen reduction reaction

The oxygen reduction reaction (ORR), the rate-limiting reaction in proton exchange membrane fuel cells, can efficiently be facilitated by properly manufactured platinum catalysts alloyed with late 3d transition metals. Herein we synthesize a platinum : cobalt nanoparticulate catalyst with a 3 : 1 atomic ratio by reduction of a dry metalorganic precursor blend within a commercial household microwave oven. The formed nanoparticles are simultaneously anchored to a carbon black support that enables large Pt surface area. Two separate microwave treatment steps were employed, where step one constitutes a fast oxidative treatment for revealing active surface area while a reductive secondary annealing treatment promotes a Pt rich surface. The resulting Pt₃Co/C catalyst (∼3.4 nm) demonstrates an enhanced ORR activity directly attributed to incorporated Co with a specific and mass activity of 704 μA cm_Pt⁻² and 352 A g_Pt⁻¹ corresponding to an increase by 279% and 66% respectively compared to a commercial Pt/C (∼1.8 nm) catalyst measured under identical conditions. The method's simplicity, scalability and novelty is expected to further assist in Pt–Co development and bring the catalyst one step closer toward commercialization and utility in fuel cells.

The oxygen reduction reaction (ORR) is efficiently facilitated platinum catalysts alloyed with Co and reveal high electrochemically active surface area via rapid microwave synthesis.

Highly Efficient Polydopamine-coated Poly(methyl methacrylate) Nanofiber Supported Platinum⁻nickel Bimetallic Catalyst for Formaldehyde Oxidation at Room Temperature

We fabricated one fibrous-membrane type of flexible and lightweight supported catalyst via loading platinum–nickel nanoparticles (PtNi NPs) directly on the polydopamine-coated polymethylmethacrylate electrospun-fibers (PMMA@PDA). The polymer support with the PDA layer provided numerous active sites, leading to well-monodispersed and sized PtNi NPs on the nanofibers. Through the rational design of PtNi NPs, the resultant catalyst system exhibited 90% conversion for decomposing HCHO (10 ppm) at room temperature with only a low dosage (0.02 g), retaining the high activity for 100 h. This superior catalytic performance stems from the formate oxidation, which was the key intermediate during HCHO decomposition, and was promoted by the existence of a sufficient Pt–OH–Ni interface in the PtNi NPs with an appropriate Pt/Ni ratio of 1:5. Such tailored Pt-based nanoparticles ideally work together with the polymer nanofibers as a support for catalytic reaction. Compared with classical catalysts, our system can handle a comparable efficiency with much lower air resistance and remarkably lower dosage. Furthermore, the membrane-like morphology provides easy handling and minimizes the leaching of catalyst nanoparticles.

Chromium-Ruthenium Oxides Supported on Gamma-Alumina as an Alternative Catalyst for Partial Combustion of Methane

Catalyst screening of γ-Al2O3-supported, single-metal and bimetallic catalysts revealed several bimetallic catalysts with activities for partial combustion of methane greater than a benchmark Pt/γ-Al2O3 catalyst. A cost analysis of those catalysts identified that the (2 wt%Cr + 3 wt% Ru)/γ-Al2O3 catalyst, denoted as 2Cr3Ru/Al2O3, was about 17.6 times cheaper than the benchmark catalyst and achieved a methane conversion of 10.50% or 1.6 times higher than the benchmark catalyst based on identical catalyst weights. In addition, various catalyst characterization techniques were performed to determine the physicochemical properties of the catalysts, revealing that the particle size of RuO2 became smaller and the binding energy of Ru 3d also shifted toward a lower energy. Moreover, the operating conditions (reactor temperature and O2/CH4 ratio), stability, and reusability of the 2Cr3Ru/Al2O3 catalyst were investigated. The stability test of the catalyst over 24 h was very good, without any signs of coke deposition. The reusability of the catalyst for five cycles (6 h for each cycle) was noticeably excellent.

Low Pt Alloyed Nanostructures for Fuel Cells Catalysts

Low-noble metal electrocatalysts are attracting massive attention for anode and cathode reactions in fuel cells. Pt transition metal alloy nanostructures have demonstrated their advantages in high performance low-noble metal electrocatalysts due to synergy effects. The basic of designing this type of catalysts lies in understanding structure-performance correlation at the atom and electron level. Herein, design threads of highly active and durable Pt transition metal alloy nanocatalysts are summarized, with highlighting their synthetic realization. Microscopic and electron structure characterization methods and their prospects will be introduced. Recent progress will be discussed in high active and durable Pt transition metal alloy nanocatalysts towards oxygen reduction and methanol oxidation, with their structure-performance correlations illustrated. Lastly, an outlook will be given on promises and challenges in future developing of Pt transition metal alloy nanostructures towards fuel cells catalysis uses.

Laser-Assisted Production of Carbon-Encapsulated Pt-Co Alloy Nanoparticles for Preferential Oxidation of Carbon Monoxide

C-encapsulated highly pure Pt_xCo_y alloy nanoparticles have been synthesized by an innovative one-step in-situ laser pyrolysis. The obtained X-ray diffraction pattern and transmission electron microscopy images correspond to Pt_xCo_y alloy nanoparticles with average diameters of 2.4 nm and well-established crystalline structure. The synthesized Pt_xCo_y/C catalyst containing 1.5 wt% of Pt_xCo_y nanoparticles can achieve complete CO conversion in the temperature range 125–175°C working at weight hourly space velocities (WHSV) of 30 L h⁻¹g⁻¹. This study shows the first example of bimetallic nanoalloys synthesized by laser pyrolysis and paves the way for a wide variety of potential applications and metal combinations.

Electrochemical synthesis of AuPt nanoflowers in deep eutectic solvent at low temperature and their application in organic electro-oxidation

Deep eutectic solvents (DESs), called a new generation of green solvents, have broad applied in synthesis of nanomaterials due to their remarkable physicochemical properties. In this work, we used a unique strategy (adding moderate water (10%) to DES) to effectively prepare nanomaterials. Flower-like AuPt alloy nanoparticles were successfully synthesized using one-step electrochemical reduction method at a low potential of −0.30 V (vs. Pt) and a low temperature of 30 °C. In this process, the DES acted as solvent and shape-directing agent. More importantly, we used the electrode modified with the as-prepared nanomaterials as the anode to the electrochemical oxidation synthesis. The glassy carbon electrode modified with the AuPt nanoflowers was directly employed to the electro-oxidation of xanthene (XT) to xanthone (XO) under a constant low potential of 0.80 V (vs. Ag/AgCl) and room temperature, with a high yield of XO. Moreover, the synthesis process was milder and more environment-friendly than conventional organic syntheses. This new strategy would have a promising application in electroorganic synthesis fields.

Random Alloyed versus Intermetallic Nanoparticles: A Comparison of Electrocatalytic Performance

As synthetic methods advance for metal nanoparticles, more rigorous studies of structure-function relationships can be made. Many electrocatalytic processes depend on the size, shape, and composition of the nanocatalysts. Here, the properties and electrocatalytic behavior of random alloyed and intermetallic nanoparticles are compared. Beginning with an introduction of metallic nanoparticles for catalysis and the unique features of bimetallic compositions, the discussion transitions to case studies of nanoscale electrocatalysts where direct comparisons of alloy and intermetallic compositions are undertaken for methanol electrooxidation, formic acid electrooxidation, the oxygen reduction reaction, and the electroreduction of carbon dioxide (CO2 ). Design and synthesis strategies for random alloyed and intermetallic nanoparticles are discussed, with an emphasis on Pt-M and Cu-M compositions as model systems. The differences in catalytic performance between alloys and intermetallic nanoparticles are highlighted in order to provide an outlook for future electrocatalyst design.

Comparative Study of the ORR Activity and Stability of Pt and PtM (M = Ni, Co, Cr, Pd) Supported on Polyaniline/Carbon Nanotubes in a PEM Fuel Cell

The oxygen reduction reaction (ORR) activity and stability of platinum (Pt) and PtM (M = Ni, Co, Cr, Pd) supported on polyaniline/carbon nanotube (PtM/PANI-CNT) were explored and compared with the commercial Pt/C catalyst (ETEK). The Pt/PANI-CNT catalyst exhibited higher ORR activity and stability than the commercial Pt/C catalyst even though it had larger crystallite/particle sizes, lower catalyst dispersion and lower electrochemical surface area (ESA), probably because of its high electrical conductivity. The addition of second metal (M) enhanced the ORR activity and stability of the Pt/PANI-CNT catalyst, because the added M induced the formation of a PtM alloy and shifted the d-band center to downfield, leading to a weak chemical interaction between oxygenated species and the catalyst surface and, therefore, affected positively the catalytic activity. Among all the tested M, the addition of Cr was optimal. Although it improved the ORR activity of the Pt/PANI-CNT catalyst slightly less than that of Pd (around 4.98%) in low temperature (60 °C)/pressure (1 atm abs), it reduced the ESA loss by around 14.8% after 1000 cycles of repetitive cyclic voltammetry (CV). In addition, it is cheaper than Pd metal. Thus, Cr was recommended as the second metal to alloy with Pt on the PANI-CNT support.

Broadening the sunlight response region with carbon dot sensitized TiO2 as a support for a Pt catalyst in the methanol oxidation reaction

Carbon dots with upconversion properties harness unused visible light and act as sensitizers for a TiO₂ supported Pt catalyst in MOR.