Search Results (214)

An anion exchange-assisted technique was used for the synthesis of platinum-decorated SnO₂ supports, providing nanocatalysts with enhanced activity for the reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP). In this study, a series of SnO₂ supports, namely SnA (synthesized almost at room temperature), SnB (hydrothermally treated at 180 °C), and SnC (annealed at 600 °C), are systematically investigated, all loaded with 1 mol% Pt from H₂PtCl₆ under identical mild conditions. The chloride ions from the SnCl₄ precursors were efficiently removed via a strong-base anion exchange reaction, resulting in highly dispersed, crystalline ~5 nm cassiterite SnO₂ particles. All Pt/SnO₂ composites displayed mesoporous structures with type IVa isotherms and H₂-type hysteresis, with SP1a (Pt on SnA) exhibiting the largest surface area (122.6 m²/g) and the smallest pores (~3.5 nm). STEM-HAADF imaging revealed well-dispersed PtOx domains (~0.85 nm), while XPS confirmed the dominant Pt⁴⁺ and Pt²⁺ species, with ~25% Pt⁰ likely resulting from photoreduction and/or interactions with Sn–OH surface groups. Raman spectroscopy revealed three new bands (260–360 cm⁻¹) that were clearly visible in the sample with 10 mol% Pt and were due to the vibrational modes of the PtOx species and Pt-Cl bonds introduced due the addition and hydrolysis of H₂PtCl₆ precursor. TGA/DSC analysis revealed the highest mass loss for SP1a (~7.3%), confirming the strong hydration of the PtOx domains. Despite the predominance of oxidized PtOx species, SP1a exhibited the highest catalytic activity (k_app = 1.27 × 10⁻² s⁻¹) and retained 84.5% activity for the reduction of 4-NP to 4-AP after 10 cycles. This chloride-free low-temperature synthesis route offers a promising and generalizable strategy for the preparation of noble metal-based nanocatalysts on oxide supports with high catalytic activity and reusability. Full article

The content of glutathione in the human body is crucial to human health, so a convenient and efficient method is needed to detect it. Herein, porous coordination network-224 (PCN-224) was modified by polydopamine to prepare polydopamine-modified PCN-224 (PCN-224-PDA) to improve the water dispersibility of the PCN-224. Monodispersed platinum nanoparticles were loaded into the PCN-224-PDA to prepare PCN-224-PDA-Pt. The PCN-224-PDA-Pt showed high peroxidase-like catalytic activity, and its catalytic activity was affected by pH and temperature. The PCN-224-PDA-Pt almost had no hemolysis of red blood cells. In addition, the PCN-224-PDA-Pt showed high affinity for 3,3′,5,5′-tetramethylbenzidine and catalytic efficiency in kinetic studies, and the type of reactive oxygen species generated during the catalytic process was hydroxyl radicals. More importantly, a colorimetric method for glutathione detection was developed based on the peroxidase-like activity of the PCN-224-PDA-Pt. The linear detection range was 1–600 μM and the detection limit reached 0.306 μM. This method shows good anti-interference capabilities and excellent recovery rates, indicating its strong potential for applications in biological detection. Full article

This paper presents the synthesis of La₂Ti₂O₇ nanoparticles by the sol–gel method starting from lanthanum nitrate and titanium alkoxide (noted as LTA). Subsequently, the lanthanum titanium oxide nanoparticles are modified with noble metals (platinum) using the chemical impregnation method, followed by a reduction process with NaBH₄. The comparative analysis of the structure and surface characteristics of the nanopowders subjected to thermal treatment at 900 °C is conducted using Fourier transform infrared spectroscopy (FT-IR), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) with energy-dispersive X-ray spectroscopy (EDX), transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray fluorescence (XRF), ultraviolet-visible (UV–Vis) spectroscopy, as well as specific surface area and porosity measurements. The photocatalytic activity is evaluated in the oxidative photodegradation of ethanol (CH₃CH₂OH) under simulated solar irradiation. The modified sample shows higher specific surfaces areas and improved photocatalytic properties, proving the better conversion of CH₃CH₂OH than the pure sample. The highest conversion of ethanol (29.75%) is obtained in the case of LTA-Pt after 3 h of simulated solar light irradiation. Full article

Background: Hyaluronicacid (HA)-conjugated nanocarriers leverage CD44 receptor overexpression on tumor cells for targeted delivery of platinum chemotherapeutics. Methods: This study compares non-functionalized (DDS1) versus HA-conjugated single-walled carbon nanotubes (DDS2) for encapsulation stability and CD44 binding of Cisplatin, Carboplatin, and Lobaplatin. Density Functional Theory calculations employed PBE-GGA with Tkatchenko–Scheffler dispersion and ZORA relativistic treatment, using a finite (8,8) armchair SWCNT (24.6 Å, H-capped) for DDS1 and an EDC/NHS-coupled HA oligomer for DDS2. We computed binding energies, HOMO–LUMO gaps, Molecular Electrostatic Potentials, and energy decompositions. Molecular docking to CD44 (PDB ID: 4PZ3) used Molegro Virtual Docker, validated by re-docking the native HA fragment (RMSD 1.79 Å). Results: DFT binding energies (eV) for DDS2 versus DDS1 were −7.92/−7.48 (Cisplatin), −8.93/−8.30 (Carboplatin), and −9.72/−9.25 (Lobaplatin), indicating enhanced stabilization by HA functionalization. Energy decomposition showed increases of ∼0.4 eV (vdW) and ∼0.2 eV (electrostatic) in DDS2. MEP maps confirmed additional negative-potential regions on DDS2, complementing drug-positive sites. Molecular docking yielded MolDock scores of −171.26 for DDS2 versus −106.68 for DDS1, reflecting stronger CD44 affinity. Docking scores indicate that HA conjugation notably strengthens the predicted affinity of CNT carriers toward the CD44 receptor ($\Delta$Score ≈ −65 kcal mol⁻¹). Conclusions: These results motivate experimental follow-up to confirm whether DDS2 can translate the in silico affinity gains into improved targeted delivery of platinum chemotherapeutics. Full article

Magnetic materials with intriguing structural and functional modifications demonstrate broad application potential in various fields, including drug delivery, absorption, extraction, separation, and catalysis. In particular, the catalytic hydrogenation of functionalized organic nitro compounds represents a significant research focus in contemporary catalysis studies. A facile synthesis of Fe₃O₄@C–Pt core-shell nanocatalysts was developed in this work through a sequential process involving (1) one-pot hydrothermal synthesis followed by N₂-annealing to obtain the Fe₃O₄@C core and (2) subsequent solvothermal deposition of platinum nanoparticles. Comprehensive characterization was performed using FT-IR, XRD, Raman spectroscopy, TEM, XPS, BET surface area analysis, TGA, and VSM techniques. The resulting magnetic nanocatalysts exhibited uniformly dispersed Pt nanoparticles and demonstrated exceptional catalytic performance in nitroarene hydrogenation reactions. Remarkably, the system showed excellent functional group tolerance across all 20 substituted nitroarenes, consistently yielding corresponding aromatic amine products with >93% conversion efficiency. Furthermore, the magnetic responsiveness of Fe₃O₄@C–Pt enabled convenient catalyst recovery through simple magnetic separation, with maintained catalytic activity over 10 consecutive reuse cycles without significant performance degradation. Full article

In conventionally used carbon-supported heterogeneous platinum catalysts for hydrogen evolution reaction (HER), low Pt utilization efficiency and poor stability, resulting from weak interactions with the carbon supports, are crucial issues. Here, we report a novel hierarchical structure of TiO_x nanoparticles embedded in porous carbon with the in situ growth of highly dispersed Pt on the TiO_x surface (Pt-TiO_x@C). The as-prepared Pt-TiO_x@C electrocatalyst showed excellent catalytic activity during HER with an overpotential of only 10 mV when the current density reached 10 mA cm⁻² and the mass activity was 9.24 A mg_Pt⁻¹ at an overpotential of 30 mV in 0.5 M H₂SO₄ solution, thus outperforming commercial Pt/C catalysts. Furthermore, it also exhibited highly stable catalytic activity over 10,000 CV cycles of an accelerated degradation test (ADT). This high HER activity and durability could be ascribed to the highly dispersed Pt feature and the strong metal–support interaction (SMSI) between Pt and TiO_x. This study also provides a simple and effective method for designing highly active and stable electrocatalysts. Full article

This study investigates the dehydrogenation of perhydrobenzyltoluene, a Liquid Organic Hydrogen Carrier (LOHC), using sulfur-doped bimetallic PtMo/Al₂O₃ catalysts. Based on previous research that highlighted the superior performance of PtMo catalysts over monometallic Pt catalysts, this work focuses on minimizing byproduct formation, specifically methylfluorene, through sulfur doping. Catalysts with low platinum content (<0.3 wt.%) were synthesized using the wet impregnation method by varying sulfur concentrations to study their impact on catalytic activity. Characterization techniques, including CO–DRIFT and CO–TPD, revealed the role of sulfur in selectively blocking low-coordinated Pt sites, thus improving selectivity and maintaining high dispersion. Catalytic tests revealed that samples with ≥0.1 wt.% sulfur achieved up to a threefold reduction in methylfluorene formation compared to the unpromoted PtMo/Al₂O₃ sample, with a molar fraction below 2% at 240 min. In parallel, these samples reached a degree of dehydrogenation (DoD) above 85% within 240 min, demonstrating that improved selectivity can be achieved without compromising catalytic performance. Full article

This study presents a straightforward hydrothermal synthesis approach to fabricate uniform and highly dispersed nanoscale Fe₃O₄ electrocatalysts for the oxygen reduction reaction (ORR). FeSO₄·7H₂O is used as the precursor, and sodium dodecyl sulfate (SDS) is incorporated as a dispersing agent to optimize particle size and dispersion. The SDS concentration plays a crucial role in controlling the particle size and distribution, with higher SDS concentrations resulting in smaller, well-dispersed particles (30–40 nm), compared to the agglomerated particles formed without SDS. The Fe₃O₄ catalyst demonstrates significant enhancement in ORR performance, with a half-wave potential of 0.091 V vs. Hg/HgO and a limiting diffusion current density of −5.50 mA cm², surpassing the performance of agglomerated Fe₃O₄ and approaching that of state-of-the-art 20% Pt/C catalysts. Additionally, the Fe₃O₄ catalyst exhibits superior stability and resistance to methanol and CO poisoning, presenting a promising alternative to platinum-based catalysts for ORR applications. This work introduces an efficient approach for the synthesis of high-performance and evenly distributed Fe₃O₄ electrocatalysts, offering a new pathway for the development of metal oxide-based ORR catalysts with enhanced activity and durability. Full article

The electrocatalytic reduction of nitric oxide and nitrogen dioxide (NOx) remains a significant challenge due to the need for stable, efficient, and cost-effective materials. This study presents a novel support system for NOx reduction in alkaline media, composed of ZrO₂-WO₃-C (ZWC), synthesized via coprecipitation. Platinum nanoparticles (10 wt.%) were loaded onto ZWC and Vulcan carbon support, using similar methods for comparison. Comprehensive physicochemical and electrochemical analyses (N₂ physisorption, XRD, XPS, SEM, TEM, and cyclic and linear voltammetry) revealed that PtZWC outperformed PtC and commercial PtEtek in NOx electrocatalysis. Notably, PtZWC exhibited the highest total electric charge for NOx reduction. At the same time, the hydrogen evolution reaction (HER) was shifted to more negative cathodic potentials, indicating reduced hydrogen coverage and a modified dissociative Tafel mechanism on platinum. Additionally, the combination of WO₃ and ZrO₂ in ZWC enhanced electron transfer and suppressed HER by reducing NO and hydrogen atom adsorption competition. While the incorporation of WO₃ and ZrO₂ lowered the surface area to 96 m²/g, it significantly improved pore properties, facilitating better Pt nanoparticle dispersion (3.06 ± 0.85 nm, as confirmed by SEM and TEM). XRD analysis identified graphite and Pt phases, with monoclinic WO₃ broadening PtZWC peaks (20–25°). At the same time, XPS confirmed oxidation states of Pt, W, and Zr and tungsten-related oxygen vacancies, ensuring chemical stability and enhanced catalytic activity. 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

How important is the support during the rational design of a catalyst? Herein, doped ceria (Zr; Pr and Tb) was used as an active support to prepare Pt catalysts (0.5 wt%) for glycerol selective oxidation. A thorough characterization of achieved catalytic systems showed that the nature of doping elements led to different physicochemical properties. The presence of surface Pr³⁺ and Tb³⁺ not only increased oxygen vacancies but also electron mobility, modifying the oxidation state of platinum particles. The redox properties of the catalyst were also affected, achieving a close interaction between the support and metal particles even in the form of Pt-O-Pr(Tb) solid solutions. Furthermore, the combination of medium-sized metal particle dispersion, strong metal–support interaction and a synergy between the amount of oxygen vacancies and Pt⁰, observed in the Pt/CeTb catalyst, led to a high turnover frequency (TOF) and increased selectivity to glyceric acid. Thus, the present study reveals how a simple structural modification of active supports, such as cerium oxide, by means of doping elements is capable of improving the catalytic performance during glycerol selective oxidation, avoiding the cumbersome methods of synthesis and activation treatments. Full article

The activities of Pt electrocatalysts modified with a prepared silica powder (with SiO₂ contents of 3 and 7 wt%) in the oxygen reduction reaction in the temperature range from 0 °C to 50 °C were investigated by the rotating disk electrode technique to evaluate their efficiency in the process of the cold start of a proton-exchange membrane fuel cell (PEMFC). An increase in the mass activity of the Pt-SiO₂/C electrocatalyst in comparison with Pt/C was observed, which can be attributed to a more dispersed distribution of platinum particles on the support surface and a decrease in their size. The activity values of the silica-modified electrocatalysts in the oxygen reduction reaction were approximately two-fold higher at 1 °C and four-fold higher at elevated temperatures of up to 50 °C in comparison with Pt/C, which makes their application in PEMFCs at low temperatures, including in the process of cold start, a promising avenue for further investigation. Full article

This study explores the development of core–shell electrocatalysts for efficient glycerol oxidation in alkaline media. Carbon-supported M@Pt/C (M = Co, Ni, Sn) catalysts with a 1:1 atomic ratio of metal (M) to platinum (Pt) were synthesized using a facile sodium borohydride reduction method. The analysis confirmed the formation of the desired core–shell structure, with Pt dominating the surface as evidenced by energy-dispersive X-ray spectroscopy (EDS). X-ray diffraction (XRD) revealed the presence of a face-centered cubic (fcc) Pt structure for Co@Pt/C and Ni@Pt/C. Interestingly, Sn@Pt/C displayed a PtSn alloy formation indicated by shifted Pt peaks and the presence of minor Sn oxide peaks. Notably, no diffraction peaks were observed for the core metals, suggesting their amorphous nature. Electrocatalytic evaluation through cyclic voltammetry (CV) revealed superior glycerol oxidation activity for Co@Pt/C compared to all other catalysts. The maximum current density followed the order Co@Pt/C > Ni@Pt/C > Sn@Pt/C > Pt/C. This highlights the effectiveness of the core–shell design in enhancing activity. Furthermore, Sn@Pt/C displayed remarkable poisoning tolerance attributed to a combined effect: a bifunctional mechanism driven by Sn oxides and an electronic effect within the PtSn alloy. These findings demonstrate the significant potential of core–shell M@Pt/C structures for designing highly active and poisoning-resistant electrocatalysts for glycerol oxidation. The presented approach paves the way for further development of optimized catalysts with enhanced performance and stability aiming at future applications in direct glycerol fuel cells. Full article

Platinum (Pt)-based heterogeneous catalysts show excellent performance for the electrocatalytic hydrogen evolution reaction (HER); however, the high cost and earth paucity of Pt means that efforts are being directed to reducing Pt usage, whilst maximizing catalytic efficiency. In this work, a two-step laser annealing process was employed to synthesize Pt single-atom catalysts (SACs) on a MOF-derived carbon substrate. The laser irradiation of a metal–organic framework (MOF) film (ZIF67@ZIF8 composite) by rapid scanning of a ns pulsed infrared (IR; 1064 nm) laser across the freeze-dried MOF resulted in a metal-loaded graphitized film. This was followed by loading this film with chloroplatinic acid (H₂PtCl₆), followed by further irradiation with an ultraviolet (UV; 355 nm) laser, resulting in pyrolysis of H₂PtCl₆ to form the SAC, along with a further reduction of the MOF to form a Pt-decorated laser-induced annealed MOF (Pt-LIA-ZIF8@ZIF67). The Pt-LIA-ZIF8@ZIF67 catalyst with a Pt loading of 0.86 wt. % exhibited exceptionally high activity for the HER in acidic conditions. The atomically dispersed Pt on the carbon substrate exhibited a small overpotential of 68.8 mV at 10 mA cm⁻² for the hydrogen evolution reaction with a mass activity 20.52 times that of a commercial Pt/C catalyst at an overpotential of 50 mV vs. RHE. Finally, we note that the synthesis method is simple, fast, and versatile, and potentially scalable for the mass production of SACs for electrocatalytic applications. Full article

This paper gives a brief description of all structural–formational zones in the Southern Urals. Riphean and Paleozoic black shale sediments with strong positive anomalies of gold and a number of other elements are widely developed within this region. This paper reports that carbonaceous shales are a very favorable geochemical environment for the primary accumulation of many industrially important elements. Under certain conditions (in the areas of magmatism, zonal metamorphism, and tectonic activity), they can serve as a source of metals and concentrate deposits, and occurrences of gold, silver, and platinoids. Among these deposits, a new type of vein-embedded gold–sulfide mineralization with dispersed gold and platinum metals, localized in rocks rich in organic carbon, has been detected. In this study, we made an attempt to summarize and systematize research materials on this issue. The presented data indicate a high potential of carbonaceous sediments in the Southern Urals, providing a good basis for further prospecting works and analytical studies. Full article