Search

The wet impregnation of additive manufactured aluminum oxide cylinders with platinum is investigated. The influence of five parameters on the penetration depth and the platinum loading is evaluated. A smaller penetration depth is obtained by increasing pH, sodium chloride concentration in the impregnation solution, decreasing impregnation solution volume, heating rate during subsequent calcination, and no vacuum during prewetting before the impregnation. A pH range of 2 to 4, a low chloride concentration, a small liquid volume, and no vacuum drawing lead to high platinum uptake. This investigation is crucial in understanding and optimizing the wet impregnation process, providing practical guidance for future research with more complex structures. [ABSTRACT FROM AUTHOR]

Realization of the full potential of single‐atom photoelectrocatalysts in sustainable energy generation requires careful consideration of the design of the host material. Here, a comprehensive methodology for the rational design of photoelectrocatalysts using anodic titanium dioxide (TiO2) nanofilm as a model platform is presented. The properties of these nanofilms are precisely engineered to elucidate synergies across structural, chemical, optoelectronic, and electrochemical properties to maximize the efficiency of the hydrogen evolution reaction (HER). These findings clearly demonstrate that thicker TiO2 nanofilms in anatase phase with pits on the surface can accommodate single‐atom platinum catalysts in an optimal configuration to increase HER performance. It is also evident that the electrolyte temperature can further enhance HER output through thermochemical effect. A judicious design incorporating all these factors into one system gives rise to a ten‐fold HER enhancement. However, the reusability of the host photoelectrocatalyst is limited by the leaching of the Pt atom, worsening HER. Density‐functional theory calculations have provided insights into the mechanism underlying the experimental observations in terms of moderate hydrogen adsorption and enhanced gas generation. This improved understanding of the critical factors determining HER performance in a model photoelectrocatalyst paves the way for future advances in scalable and translatable photoelectrocatalyst technologies. [ABSTRACT FROM AUTHOR]

Rational construction of platinum (Pt)‐based single‐atom catalysts (SACs) with high utilization of active sites holds promise to achieve superior electrocatalytic alkaline HER performance, which requires the assistance of functional supports. In this work, a novel catalytic configuration is reported, namely, Pt SACs anchored on the nickel‐chromium oxides labeled as Pt SACs‐NiCrO3/NF. The mechanism associated with the metal‐support interaction (MSI) for synergy co‐catalysis that empowers efficient HER on Pt SACs‐NiCrO3/NF is clarified. Specifically, the modulated electron structure in Pt SACs‐NiCrO3 manipulates the interface microenvironment, mediating a more free water state, which is beneficial to accelerate front water dissociation behavior on the oxide support. Besides, the homogeneously distributed Pt sites with the created near‐acidic state ensure the subsequent fast proton‐involved reaction. All these determine the comprehensively accelerating HER kinetics. Consequently, Pt SACs‐NiCrO3/NF deliverers considerable HER performance, with overpotentials (η10/η100) of 23/122 mV, high mass activity of 382.77 mA mg−1Pt. When serving in an alkaline water‐based anion exchange membrane electrolytic cell (AEMWE), Pt SACs‐NiCrO3/NF also presents excellent performance (100 mA cm−2 at the cell voltage of 1.51 V and stable up to 100 h), confirming its good prospect. [ABSTRACT FROM AUTHOR]

In this paper, platinum nanoparticles with a size of less than 50 nm were rapidly and successfully synthesized in low-temperature molten salt using a microwave method. The morphology and structure of the product were characterized by SEM, TEM, EDX, XRD, etc. The TEM and SEM results showed that the prepared product was a nanostructure with concave and uniform size. The EDX result indicated that the product was pure Pt, and the XRD pattern showed that the diffraction peaks of the product were consistent with the standard spectrum of platinum. The obtained Pt/C nanoparticles exhibited remarkable electrochemical performance in a formic acid catalytic oxidation reaction (FAOR), with a peak mass current density of 502.00 mA·mg−1Pt and primarily following the direct catalytic oxidation pathway. In addition, in the chronoamperometry test, after 24 h, the mass-specific activity value of the Pt concave NPs/C catalyst (10.91 mA·mg−1Pt) was approximately 4.5 times that of Pt/C (JM) (2.35 mA·mg−1Pt). The Pt/C NPs exhibited much higher formic acid catalytic activity and stability than commercial Pt/C. The microwave method can be extended to the preparation of platinum-based alloys as well as other catalysts. [ABSTRACT FROM AUTHOR]

In this work hydrodeoxygenation of various lignin-derived model compounds and their mixture was studied over platinum catalysts based on porous aromatic frameworks (PAF) doped with Bronsted acid sites. Two catalysts, Pt-PAF-30-SO3H(5.0) and Pt-PAF-30-SO3H(7.5), with almost identical platinum loading of 5.1 and 4.7 wt. % but different sulfur concentration of 4.46 and 6.96 wt. % respectively, were synthesized using a method that allows to obtain highly uniform distribution of nanoparticles in the porous structure of the support. The HDO reaction pathways of lignin substrates with different structures were discussed, and the influence of the platinum source chosen for the synthesis of the catalyst on the activity and the selectivity of the latter was studied. We have demonstrated high stability of catalyst (for at least a 7 h reaction) and have confirmed the great activity of the Pt-PAF-30-SO3H(7.5) catalyst in HDO reactions with a large number of lignin bio-oil model compounds. Pt-PAF-30-SO3H(7.5) was also tested in the hydrodeoxygenation of a model mixture of aromatic substrates taken in proportions contained in lignin bio-oil. The selectivity to naphthenic hydrocarbons—products of the complete hydrodeoxygenation—was 54%. [ABSTRACT FROM AUTHOR]

Alloying and solid‐solution formation is a powerful technique that enhances and adds properties through elemental mixing, but unfortunately, some elements simply cannot mix as their chemical nature prevents a thermodynamically stable structure. For example, the inherent nobility of platinum group metals does not favor bond formation and precludes their incorporation into higher (boron‐rich) metal borides. However, we demonstrate that when using five or more constituents, the higher mixing entropy will overcome these chemical limitations and form a stable high‐entropy alloy, demonstrating the formation of new compounds with substituents that are seemingly impossible with a traditional metal alloying approach. The high‐entropy boride (HEB) Al0.2Nb0.2Pt0.2Ta0.2Ti0.2B2 was synthesized, where platinum was forced to occupy a 12‐coordinate site, sandwiched between honeycomb borophene sheets. In addition to the unusual coordination, the boron serves as a poison panacea. Pure platinum is strongly susceptible to sulfur poisoning by adsorption, rendering a platinum catalyst ineffective. Boron is known to be resistant to sulfur poisoning. The boron sheets present in the HEB shield the platinum from sulfur while maintaining high catalytic activity. This is confirmed with the facile hydrogenation of thiol‐containing nitro compounds, where the HEB resists sulfur poisoning while retaining its high catalytic activity. [ABSTRACT FROM AUTHOR]

Wet biomass such as waste sludge in effluent treatment plants and microalgae can be effectively utilized by producing H 2 -rich gases through aqueous-phase reforming (APR). Polyols, carbohydrates, proteins and humic substances are some classes of compounds present in such biofeeds. In this work, platinum catalyst was supported on hydrotalcite (HTlc) carrier and applied for APR of the respective model compounds, viz. glycerol, glucose, glycine and humic acid. H 2 , CH 4 and carbon oxides were the gaseous products. It was found that the catalyst performance varied when it was made differently. The 1% Pt/HTlc and 5% Pt/HTlc catalysts were characterized using X-ray diffraction, N 2 -physisorption, scanning electron microscopy. The optimal catalyst, whose Pt content was 5 wt %, was characterized using electron microscopy and X-ray photoelectron spectroscopy techniques. Catalyst efficacy trials were performed between 215 and 245 °C using catalyst loadings (ω) between 2 and 6 kg/m3. The initial concentration of all substrates was 1 wt %. The system pressure was equal to 3.9 MPa. The values of carbon conversion to gas phase (C-to-G conversion) after 3 h at T = 245 °C and ω = 6 kg/m3 were so: glycerol-37.3, glucose-26.7 and glycine-15.6%. The respective values of H 2 yield (Y–H 2) were: glycerol-22.8, glucose-14.7 and glycine-5.4%. The values of Y–H 2 were very low for the reaction with humic acid. The results of this model compound study will provide useful insight into APR of wet biofeeds. • Pt/HTlc was applied for APR of glycerol, glucose, glycine and humic acid. • Pt (4.6%), Mg (17.7%) and Al (5.2%) content in Pt/HTlc was found using EDX. • H 2 , CH 4 and carbon oxides were the gaseous products. • C-to-G conversion at 245 °C after 3 h was glycerol-37, glucose-27 and glycine-16%. • Humic acid provided very low H 2 yield. [ABSTRACT FROM AUTHOR]

Hydrogen fuel cells and water electrolyzers hold significant potential for net zero emission and climate change mitigation, but their practical applications are limited by the use of the precious-metal platinum as catalysts. In this study, a one-pot method is developed for the synthesis of PtCo x alloys supported on hybrid carbon materials, and it is found that the developed catalysts with reduced Pt loading can act as excellent bifunctional catalysts for both oxygen reduction reaction (ORR) and hydrogen evolution reaction (HER). Morphology and composition characterizations indicate uniform dispersion and adjustable composition of PtCo x alloys with the particle size of ∼3 nm on the carbon support. Among them, Pt 3 Co/C achieves the highest ORR performance with a high mass activity of 179.23 A/g and a specific activity of 3.15 A/m2 in acidic condition, and an extremely low overpotential of 47.6 mV at 10 mA/cm2 in alkaline media as a HER catalyst. This study presents a cost-effective approach for the development of high performance PtCo x /C catalysts, and confirms their potential application in hydrogen energy technologies. [Display omitted] • A facile one-pot synthesis approach of PtCo x /C is developed. • The PtCo x particles with the size of ∼3 nm disperses uniformly on carbon support. • The Pt 3 Co/C exhibits excellent catalytic activity towards both ORR and HER. • Catalytic performance can be optimized by adjusting synthesis conditions. [ABSTRACT FROM AUTHOR]

We conducted an in‐depth exploration of the in vitro activities of the dinuclear Mn2L2Ac and Mn2L2 complexes (where HL=2‐{[di(2‐pyridyl)methylamino]‐methyl}phenol), possessing dual superoxide dismutase (SOD) and catalase (CAT) activity. We investigated these complexes both individually and in conjunction with various Pt(II)‐complexes, either as mixtures or as the Mn2‐Pt adducts. Our findings revealed a notable up to 50 % enhancement in the viability of healthy human breast cells, contrasted with a viability decrease as low as 50 % in breast cancer cells upon combined treatments with Mn2 SOD mimics and Pt(II) complexes. Specifically, we synthesized and characterized the self‐assembled Mn2‐Pt adducts (isolated Mn2L2Pt and in situMn2L2Pt'), linking Mn2L2‐core with the carboxylate group of PtDAPCl2 (dichloro(2,3‐diaminopropionic acid) platinum(II)). The SOD activity of the isolated Mn2L2Pt adduct (kSOD=1.7×107 M−1 s−1) remained intact. Through in vitro cell viability assessments, ROS levels, cellular Mn uptake and proteomics measurements, we elucidated key mechanisms underlying the observed biological effects. We demonstrated that Mn2‐containing formulations predominantly target mitochondrial processes, differently affecting the proteome of cancerous and healthy cells. They induced downregulation of H2S signaling and expression of mitochondrial complex I and III, as well as increased oxidative phosphorylation pathways and upregulation of EGFR in cancer cells. In contrast, healthy cells showed a decrease in EGFR expression and a moderate enrichment in oxidative phosphorylation pathways. [ABSTRACT FROM AUTHOR]

Phosphonic acid (PA) self‐assembled monolayers (SAMs) were deposited onto Pt/Al2O3 catalysts to modify the support to enable control over CO2 adsorption and CO2 hydrogenation activity. Significant differences in catalytic activity toward CO2 hydrogenation (reverse water‐gas shift, RWGS) were observed after coating Al2O3 with PAs, suggesting that the reaction was mediated by CO2 adsorption on the support. Amine‐functionalized PAs were found to outperform their alkyl counterparts in terms of activity, however there was little effect of amine location in the SAM (i. e., spacing between the amine functional group and phosphonate attachment group). One amine‐PA and one alkyl‐PA, aminopropyl phosphonic acid (C3NH2PA) and methyl phosphonic acid (C1PA), respectively, were investigated in more detail. The C3NH2PA‐modified catalyst was found to bind CO2 as a combination of carbamate and bicarbonate. Additionally, at 30 °C, both PAs were found to reduce CO2 adsorption uptake by approximately 50 % compared to unmodified 5 %Pt/Al2O3. CO2 adsorption enthalpy was measured for the catalysts and found to be strongly correlated with hydrogenation activity, with the trend in binding enthalpy and CO2 hydrogen rate trending as uncoated >C3NH2PA>C1PA. PA SAMs were found to have weaker effects on CO binding and CO selectivity, consistent with selective modification of the Al2O3 support by the PAs. [ABSTRACT FROM AUTHOR]

The quality of in situ XAS of electrochemical systems is highly sensitive to electrode disturbances, such as gas evolution and gas consumption at an electrolyte/catalyst interface. A novel in situ spectro‐electrochemical X‐ray absorption spectroscopy (SPEC‐XAS) cell is presented as a new tool for the characterisation of gas evolving and consuming electrocatalysts at high overpotentials. By utilising a thin, porous membrane with efficient electrolyte and gas circulating loops, an improved three phase interface is established that enabled efficient gas supply and minimised the interference from bubble formation. X‐ray absorption spectroscopy (XAS) measurements were conducted in fluorescence mode with three experiments selected to demonstrate the cell's performance. The first two reactions; an in‐situ study of a highly active amorphous iridium oxide catalyst during the oxygen evolution reaction (OER) and an in‐situ study of copper oxide during the carbon dioxide reduction reaction (CO2RR) are used to exemplify the XAS data quality achieved under operational conditions. Thirdly, a detailed XAS investigation of a highly dispersed platinum catalyst during the oxygen reduction reaction (ORR) is presented, along with comparative data in nitrogen. These measurements show the retention of oxygen on the surface of the platinum metal particles down to 0.48 V (vs. RHE), well below the platinum oxide reduction peak. [ABSTRACT FROM AUTHOR]

The combination of fluidity and metallic conductivity has attracted considerable attention to liquid metal (LM), but its development remains challenging due to enormous surface tension. Here, vinyl‐terminated silicone oil and platinum catalyst are added to LM to reduce its surface tension, which develops a special type of liquid‐metal‐silicone (LMS) ink with a catalyst diffusion effect. Combined with an embedded three‐dimentional (3D) printing method, the LMS ink is printed on the support matrix, and the catalyst diffuses outward along the print path to cure the silicone around it, directly constructing self‐encapsulated conductive composites with excellent conductivity and self‐encapsulated flexible tactile sensors based on triboelectric nanogenerator (TENG). The sensor exhibits excellent sensitivity (0.308 V kPa−1), high linearity (≈0.99), and good durability (over 10 000 cycles). Furthermore, when used in flexible wearable electronics, the sensor demonstrates a good performance with an accuracy of ≈96% in classifying different human postures using a convolutional neural network. Finally, through embedded 3D printing with LMS ink and silicone ink, a somatosensory soft robotic gripper with complex cavity structures is designed and manufactured in one step, achieving the all‐in‐one integration of sensors and actuators. This study shows great application potential in flexible electronics and soft robotic systems. [ABSTRACT FROM AUTHOR]

Phosphonic acid (PA) self‐assembled monolayers (SAMs) were deposited onto Pt/Al2O3 catalysts to modify the support to enable control over CO2 adsorption and CO2 hydrogenation activity. Significant differences in catalytic activity toward CO2 hydrogenation (reverse water‐gas shift, RWGS) were observed after coating Al2O3 with PAs, suggesting that the reaction was mediated by CO2 adsorption on the support. Amine‐functionalized PAs were found to outperform their alkyl counterparts in terms of activity, however there was little effect of amine location in the SAM (i. e., spacing between the amine functional group and phosphonate attachment group). One amine‐PA and one alkyl‐PA, aminopropyl phosphonic acid (C3NH2PA) and methyl phosphonic acid (C1PA), respectively, were investigated in more detail. The C3NH2PA‐modified catalyst was found to bind CO2 as a combination of carbamate and bicarbonate. Additionally, at 30 °C, both PAs were found to reduce CO2 adsorption uptake by approximately 50 % compared to unmodified 5 %Pt/Al2O3. CO2 adsorption enthalpy was measured for the catalysts and found to be strongly correlated with hydrogenation activity, with the trend in binding enthalpy and CO2 hydrogen rate trending as uncoated >C3NH2PA>C1PA. PA SAMs were found to have weaker effects on CO binding and CO selectivity, consistent with selective modification of the Al2O3 support by the PAs. [ABSTRACT FROM AUTHOR]

The growing demand for hydrogen–air fuel cells with a proton-exchange membrane has increased interest in the development of scalable technologies for the synthesis of Pt/C catalysts that will allow us to fine-tune the microstructure of such materials. We have developed a new in situ technique for controlling the kinetics of the transformation of a platinum precursor into its nanoparticles and deposited Pt/C catalysts, which might be applicable during the liquid-phase synthesis in concentrated solutions and carbon suspensions. The technique is based on the analysis of changes in the redox potential and the reaction medium coloring during the synthesis. The application of the developed technique under conditions of scaled production has made it possible to obtain Pt/C catalysts with 20% and 40% platinum loading, containing ultra-small metal nanoparticles with a narrow size distribution. The electrochemically active surface area of platinum and the mass activity of synthesized catalysts in the oxygen electroreduction reaction have proved to be significantly higher than those of commonly used commercial analogs. At the same time, despite the small size of nanoparticles, the catalysts' degradation rate turned out to be the same as that of commercial analogs. [ABSTRACT FROM AUTHOR]

The catalytic activity of platinum for CO oxidation depends on the interaction of electron donation and back‐donation at the platinum center. Here we demonstrate that the platinum bromine nanoparticles with electron‐rich properties on bromine bonded with sp‐C in graphdiyne (PtBr NPs/Br‐GDY), which is formed by bromine ligand and constitutes an electrocatalyst with a high CO‐resistant for methanol oxidation reaction (MOR). The catalyst showed peak mass activity for MOR as high as 10.4 A mgPt−1, which is 20.8 times higher than the 20 % Pt/C. The catalyst also showed robust long‐term stability with slight current density decay after 100 hours at 35 mA cm−2. Structural characterization, experimental, and theoretical studies show that the electron donation from bromine makes the surface of platinum catalysts highly electron‐rich, and can strengthen the adsorption of CO as well as enhance π back‐donation of Pt to weaken the C−O bond to facilitate CO electrooxidation and enhance catalytic performance during MOR. The results highlight the importance of electron‐rich structure among active sites in Pt‐halogen catalysts and provide detailed insights into the new mechanism of CO electrooxidation to overcome CO poisoning at the Pt center on an orbital level. [ABSTRACT FROM AUTHOR]

In a polymer electrolyte membrane (PEM) fuel cell, the following degradation mechanisms are associated with the catalyst particles and their support: carbon support corrosion triggered by carbon and platinum oxidation, platinum dissolution with redeposition, and particle detachment with agglomeration. In this work, an electrochemical model for those degradation effects is presented as well as its coupling with a three‐dimensional computational fluid dynamics PEM fuel cell performance model. The overall model is used to calculate polarization curves and current density distributions of a PEM fuel cell in a fresh and aged state as well as the degradation process during an accelerated stress test with 30 000 voltage cycles. The obtained simulation results are compared to measurements on a three‐serpentine channel PEM fuel cell with an active area of 25 cm2 under various temperatures and humidities. The experimental data are obtained with a segmented test cell using respective degradation protocols and test conditions proposed by the United States Department of Energy. In addition to the temperature and humidity changes, the influence of geometry and material parameters on the degree of degradation and the resulting fuel cell performance is explored in detail. [ABSTRACT FROM AUTHOR]

Internal combustion engine fueled by carbon-free hydrogen (H2-ICE) offers a promising alternative for sustainable transportation. Herein, we report a facile and universal strategy through the physical mixing of Pt catalyst with zeolites to significantly improve the catalytic performance in the selective catalytic reduction of nitrogen oxides (NOx) with H2 (H2-SCR), a process aiming at NOx removal from H2-ICE. Via the physical mixing of Pt/TiO2 with Y zeolite (Pt/TiO2 + Y), a remarkable enhancement of NOx reduction activity and N2 selectivity was simultaneously achieved. The incorporation of Y zeolite effectively captured the in-situ generated water, fostering a water-rich environment surrounding the Pt active sites. This environment weakened the NO adsorption while concurrently promoting the H2 activation, leading to the strikingly elevated H2-SCR activity and N2 selectivity on Pt/TiO2 + Y catalyst. This study provides a unique, easy and sustainable physical mixing approach to achieve proficient heterogeneous catalysis for environmental applications. The integration of Pt-oxide catalyst systems with zeolites demonstrates considerable promise for reducing nitrogen oxide emissions at low temperatures from fossil-fuel or hydrogen-powered internal combustion engines. [ABSTRACT FROM AUTHOR]

A high‐efficiency PtZnCd nanozyme was screened with density functional theory (DFT) and unique d‐orbital coupling features for sensitive enrichment and real‐time analysis of CO‐releasing molecule‐3 (CORM‐3). Multicatalytic sites in the nanozyme showed a high reactivity of up to 72.89 min−1 for peroxidase (POD)‐like reaction, which was 2.2, 4.07, and 14.67 times higher than that of PtZn (32.67 min−1), PtCd (17.89 min−1), and Pt (4.97 min−1), respectively. Normalization of the catalytic sites showed that the catalytic capacity of the active site in PtZnCd was 2.962 U μmol−1, which was four times higher than that of a pure Pt site (0.733 U μmol−1). DFT calculations showed that improved d‐orbital coupling between different metals reduces the position of the center of the shifted whole d‐band relative to the Fermi energy level, thereby increasing the contribution of the sites to the electron transfer from the active center, accompanied by enhanced substrate adsorption and intermediate conversion in the catalytic process. The potential adsorption principle and color development mechanism of CORM‐3 on PtZnCd were determined, and its practical application in drug metabolism was validated in vitro and in zebrafish and mice models, demonstrating that transition‐metal doping effectively engineers high‐performance nanozymes and optimizes artificial enzymes. [ABSTRACT FROM AUTHOR]

Given her unrivalled proficiency in the synthesis of all molecules of life, nature has been an endless source of inspiration for developing new strategies in organic chemistry and catalysis. However, one feature that remains thus far beyond chemists' grasp is her unique ability to adapt the productivity of metabolic processes in response to triggers that indicate the temporary need for specific metabolites. To demonstrate the remarkable potential of such stimuli‐responsive systems, we present a metabolism‐inspired network of multicatalytic processes capable of selectively synthesising a range of products from simple starting materials. Specifically, the network is built of four classes of distinct catalytic reactions—cross‐couplings, substitutions, additions, and reductions, involving three organic starting materials—terminal alkyne, aryl iodide, and hydrosilane. All starting materials are either introduced sequentially or added to the system at the same time, with no continuous influx of reagents or efflux of products. All processes in the system are catalysed by a multifunctional heteronuclear PdII/PtII complex, whose performance can be controlled by specific additives and external stimuli. The reaction network exhibits a substantial degree of orthogonality between different pathways, enabling the controllable synthesis of ten distinct products with high efficiency and selectivity through simultaneous triggering and suppression mechanisms. [ABSTRACT FROM AUTHOR]

To reduce the manufacturing cost of polymer electrolyte membrane fuel cells (PEMFCs), tests targeting the decrease of reaction temperature and the amount of reducing agent in the polyol method for the synthesis of Pt/C catalysts were conducted. The reaction temperature in the polyol method was changed from 50 to 160 °C. Through XRD and TGA, it was determined that the reduction of platinum ions by the oxidation of ethylene glycol started at 70 °C. Below a 60 °C reaction temperature, Pt (1 1 1) peaks in XRD were barely visible, indicating that no deposition occurred. TEM revealed that Pt particles were well-dispersed above a 100 °C reaction temperature. For manufacturing platinum catalysts using the polyol method, it was found that 100 °C is the optimal synthesis temperature. Additionally, it was found that similar performance can be achieved by adding water to decrease the amount of ethylene glycol during synthesis. Finally, considering various analyses, it is evident that the dispersion, size, and crystallinity of platinum particles had the most significant impact on performance. [ABSTRACT FROM AUTHOR]

The authors reveal aspects of the formation of platinum nanoparticles and chemical coating of carbon support surfaces when preparing model (0.5%Pt/Sibunite) and industrial (0.5%Pt/Graphite) catalysts for synthesizing hydroxylamine sulfate via the hydrogenation of NO in a solution of H2SO4. It is shown that functionalizing the surfaces of supports with nitrogen-containing groups while depositing platinum ensures not only the dispersion of metal but a strong increase in its selectivity toward hydroxylamine sulfate. It is assumed that maximum selectivity is characteristic of active sites being single atoms or small platinum clusters bound to the nitrogen-containing ligands of a carbon surface. [ABSTRACT FROM AUTHOR]

Platinum nanoclusters (PtNCs) are promising in catalysis due to their large specific surface area and unique physicochemical properties. Here, ultrasmall and uniform PtNCs are facilely synthesized with the mediation of amidine‐functionalized polyamines patched on mesoporous poly(divinylbenzene‐4‐vinylbenzyl chloride) beads. When each ligand patch has 14 amidines, ultrafine PtNCs (with the size as low as 1.1±0.1 nm) are formed as a result of several factors: deprotonated amidines (carbenes) strongly passivate on Pt atoms, amidines act as co‐stabilizers along with weak polyamine ligands, and PtNCs are confined to discrete ligand patches. When one ligand patch contains 9.3 amidines, the resulting PtNCs (1.7±0.3 nm) reach the highest turnover frequency of 536 h−1 for the catalytic reduction of 4‐nitrophenol in a batch reaction. This catalyst remains rather stable in a continuous flow test as a 4‐nitrophenol conversion of over 95 % is still achieved after running consecutively for 10 h. [ABSTRACT FROM AUTHOR]

Transition metal sulfide catalysts with abundant reserves and low prices exhibit high activity for hydrogen production from photocatalytic water splitting and are ideal choices to replace precious metal platinum catalysts. The preparation methods, structural morphologies and hydrogen production rates of transition metal sulfide catalysts for hydrogen production from photocatalytic water splitting were reviewed. Strategies for improving the efficiency of hydrogen production from photocatalytic water splitting by transition metal sulfide catalysts and their composite catalysts were discussed, including expanding the light absorption range, enhancing the separation of photogenerated electron-hole pairs and promoting catalyst surface reactions, to prepare more efficient transition metal sulfide catalysts that meet commercial requirements. At last, the future research trends in the field of hydrogen production from photocatalytic water splitting by transition metal sulfide catalysts were prospected. [ABSTRACT FROM AUTHOR]

Copyright of Precious Metals / Guijinshu is the property of Precious Metals Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The S-doped PtMn concave cubes enclosed with high index facet and regulatable surface strain are successfully fabricated by two steps hydrothermal method. The PtMnS 1.1 catalyst exhibits superior catalytic properties for ethanol electrooxidation reaction in acidic and alkaline media, which is ascribed to the optimal surface strain and unsaturated surface-active sites. [Display omitted] Surface strain engineering has proven to be an efficient strategy to enhance catalytic properties of platinum (Pt)-based catalysts for electrooxidation reactions. Herein, the S-doped PtMn concave cubes (CNCs) enclosed with high index facets (HIFs) and regulatable surface strain are successfully fabricated by two steps hydrothermal method. The S element with electrophilic property can modify the near-surface of PtMn nanocrystals, altering the electronic structure of Pt to effectively regulate the adsorption/desorption of intermediates in the ethanol electrooxidation reaction (EOR). The PtMnS 1.1 catalyst with optimal surface strain delivered extraordinary catalytic performance on EOR in acidic media, with a specific activity of 2.88 mA/cm2 and mass activity of 1.10 mA/μg Pt , which is 4.1 and 2.2 times larger than that of state-of-the-art Pt/C catalyst, respectively. Additionally, the PtMnS 1.1 catalyst also achieve excellent catalytic properties in alkaline electrolyte for EOR. The results of kinetic studies indicated that the surface strain and modified electronic structure can degrade the activation energy barrier during the process of EOR, which is beneficial for enhance the reaction rate. This work provides a promising approach to construct highly efficient electrocatalysts with tunable surface strain effects for clean energy electro-chemical reactions. [ABSTRACT FROM AUTHOR]

In order to improve the dispersibility of inorganic fillers and enhance its ceramifiable flame‐retardant efficiency, the ceramifiable flame‐retardant silicone rubber composites were prepared using glass powder, zinc borate, ammonium polyphosphate, mica powder, platinum catalyst as ceramifiable flame‐retardant agent, and various silane coupling agents as interfacial modifier. The micromorphology, mechanical properties, flame retardancy, thermal stability, and combustion behavior of ceramifiable flame‐retardant silicone rubber composites, as well as the flexural strength of the corresponding ceramics generated after pyrolysis of the composites were examined. The results reveal that the inclusion of silane coupling agents improves the dispersibility of ceramifiable flame‐retardant agents substantially. The mechanical properties, flame retardancy, thermal stability, and combustion behavior of ceramifiable flame‐retardant silicone rubber composites are all improved. When compared to a composite without a silane coupling agent, the tensile strength of the composite can be improved by up to 1.9 times. Only 0.5phr silane coupling agent is required to raise the vertical combustion rating from V‐1 to V‐0, and the composite with 3 phr KH570 has a LOI value of 38.6. Meanwhile, the heat release rate of the composite is reduced to a certain extent, and the time to ignition and residue are dramatically enhanced after the addition of silane coupling agent in the cone calorimetry test. Moreover, flexural strength of the corresponding ceramics generated after pyrolysis of the composites rapidly increases with increasing silane coupling agent content, which can reach to 24.7 MPa with addition of 3 phr KH570. [ABSTRACT FROM AUTHOR]

Tailoring and optimizing Pt-based catalysts for the hydrogen evolution reaction (HER) is crucial for efficient energy conversion and storage. Reducing the amount of Pt used in HER catalysts is of paramount importance to enhance their application potential. It is highly challenging to precisely tailor Pt-based catalysts with the desired composition, uniform size, and homogeneous distribution, all while maintaining high catalytic activity and stability. Herein, the reducibility of H x MoO 3 is meticulously controlled by the incorporated amount of H+ ions into MoO 3 , enabling the preparation of size-controllable Au nano-cores. Furthermore, a low-loading PtCo shell is constructed on the surface of the Au nano-cores to generate Au@PtCo core-shell heterostructures. The distinctive core-shell structure not only augments the utilization of the Pt atom but also facilitates the alteration of the electronic configuration in PtCo, thereby escalating the catalytic efficiency for HER. By utilizing the dual-active sites of PtCo shell, the overpotential is reduced to only 95 mV at a current density of 10 mA/cm2, accompanied by significant improvements in kinetics and enhanced stability. Furthermore, the presented method is universal and can be utilized to fabricate analogous Au@PtFe, Au@PtNi, and Au@PtCu catalysts. Tailored preparation of Pt-based catalysts using sacrificial template method is presented. H x MoO 3 exhibits controllable reducibility, making it an ideal template for size-controllable Au nanoparticle synthesis. These Au nanoparticles support PtCo dual catalytic sites, forming the Au@PtCo structure with exceptional catalytic activity and stability for alkaline HER. The method is also extendable to prepare Au@PtM (M = Fe, Ni, Cu, etc.) catalysts. [Display omitted] • H x MoO 3 exhibits controllable reducibility. • H x MoO 3 as a template for metal preparation. • Au@PtCo exhibits exceptional catalytic activity and stability for HER. [ABSTRACT FROM AUTHOR]

Single-atomic metal catalysts are attractive for green chemistry in terms of their outstanding catalytic performance and savings in precious metal usage owing to maximized metal utilization, including anode catalysts in polymer electrolyte fuel cells (PEFCs). Heteroatom-doped porous carbons are extensively used as supports, where the heteroatoms contribute to the immobilization of single-atomic metals. However, high-content doping of heteroatoms, especially sulphur (S), into carbon supports is still challenging because S species can be readily desorbed during heat treatment. Herein, we present a bottom-up fabrication approach for S-rich porous carbons from molecular precursors via a thermal polymerization process. A simple carbonization of molecules with thermally stable S-containing building blocks and polymerizable ethynyl moieties at 900 °C yields microporous carbon materials with record-high S content (over 15 wt%). The abundant S species function as an effective anchoring site for single-atomic platinum (Pt) species. Toward anode catalysts in PEFCs, the prepared single-atomic Pt catalysts efficiently promote the electrochemical hydrogen oxidation reaction, whose activity is comparable to that of commercial Pt/C, despite the significantly low Pt loading amount. [ABSTRACT FROM AUTHOR]

The oxygen reduction reaction (ORR) catalyzed by efficient and economical catalysts is critical for sustainable energy devices. Although the newly-emerging atomically dispersed platinum catalysts are highly attractive for maximizing atomic utilization, their catalytic selectivity and durability are severely limited by the inflexible valence transformation between Pt and supports. Here, we present a structure by anchoring Pt atoms onto valence-adjustable CuOx/Cu hybrid nanoparticle supports (Pt1-CuOx/Cu), in which the high-valence Cu (+2) in CuOx combined with zero-valent Cu (0) serves as a wide-range valence electron reservoir (0‒2e) to dynamically adjust the Pt 5d valence states during the ORR. In situ spectroscopic characterizations demonstrate that the dynamic evolution of the Pt 5d valence electron configurations could optimize the adsorption strength of *OOH intermediate and further accelerate the dissociation of O = O bonds for the four-electron ORR. As a result, the Pt1-CuOx/Cu catalysts deliver superior ORR performance with a significantly enhanced four-electron selectivity of over 97% and long-term durability. The electrochemical oxygen reduction reaction catalyzed by efficient and economical catalysts is critically important for sustainable energy devices. Here the authors report anchoring Pt atoms onto valence-adjustable CuOx/Cu hybrid nanoparticle to dynamically tune the Pt 5d valence states at the initial reaction stage for optimizing oxygen reduction performance. [ABSTRACT FROM AUTHOR]

This document discusses the importance of renewable and sustainable energy sources in light of the negative impact of fossil fuels on climate change. It focuses on the development of advanced catalytic materials for fuel cells, batteries, electrolysers, and solar cells. The research explores various types of fuel cells and investigates the mechanisms and kinetics of energy conversion reactions. Specific contributions include the oxidation of borohydride and the oxygen evolution reaction. The document also explores the use of PET bottle waste and perovskite-structured catalysts for energy conversion. The goal is to develop cost-effective and efficient catalysts for renewable energy generation and storage. The article discusses several studies on the development of catalytic materials for energy conversion reactions. These studies highlight the importance of diverse catalysts in renewable energy applications. [Extracted from the article]

AbstractA non-isothermal, two-dimensional, two-phase fuel cell agglomerate model is used, and studies are done on how platinum loading and catalyst layer thickness affect heat transfer in fuel cells. Results indicate that as the cathode platinum content and catalyst layer (CL) thickness rise, the electrical property is improved. The maximum power density corresponding to the platinum loading of 0.40 mg/cm2 increases by 8.92% compared with 0.20 mg/cm2, and the maximum power density corresponding to the CL thickness of 17.5 µm increases by 4.63% compared with 10.0 µm. Temperature variation trends in CLs from entry to exit and inside the cell along the thickness direction do not change. Furthermore, with the CL thickness as well as platinum content increasing, the temperature increment inside cathode gas diffusion layer as well as CL is more obvious, and temperature distribution uniformity within the cell deteriorates. The impact of platinum loading on the temperature in the cell is more obvious than that of CL thickness. In the selection about platinum content and thickness of CL, temperature distribution uniformity and electrical property should be weighed. [ABSTRACT FROM AUTHOR]

The progress of proton exchange membrane fuel cells (PEMFCs) in the clean energy sector is notable for its efficiency and eco-friendliness, although challenges remain in terms of durability, cost and power density. The oxygen reduction reaction (ORR) is a key sluggish process and although current platinum-based catalysts are effective, their high cost and instability is a significant barrier. Single-atom catalysts (SACs) offer an economically viable alternative with comparable catalytic activity for ORR. The primary concern regarding SACs is their operational stability under PEMFCs conditions. In this article, we review current strategies for increasing the catalytic activity of SACs, including increasing active site density, optimizing metal center coordination through heteroatom doping, and engineering porous substrates. To enhance durability, we discuss methods to stabilize metal centers, mitigate the effects of the Fenton reaction, and improve graphitization of the carbon matrix. Future research should apply computational chemistry to predict catalyst properties, develop in situ characterization for real-time active site analysis, explore novel catalysts without the use of platinum-based catalysts to reduce dependence on rare and noble metal, and investigate the long-term stability of catalyst under operating conditions. The aim is to engineer SACs that meet and surpass the performance benchmarks of PEMFCs, contributing to a sustainable energy future. [ABSTRACT FROM AUTHOR]

Developing and fabricating a heterogeneous material for efficient dehydrogenation of formic acid (FA) to H2 coupled with hydrogenation of CO2 back to FA is a promising strategy to forming a carbon‐neutral CO2‐mediated hydrogen energy release‐storage system, which remains challenging. Herein, a facile one‐step ultrahigh‐temperature method of arc‐discharge route for synthesizing efficient single‐crystal α‐MoC supported platinum catalysts with high dispersion of Pt single atoms (SAs), nanoclusters (NCs), and nanoparticles (NPs) is reported. These catalysts exhibit remarkable performance for the adsorption properties and chemical conversion of small molecules including room‐temperature FA dehydrogenation, CO2 hydrogenation to FA (formate), and low‐temperature CO oxidation reactions. The enhanced electron transfer from MoC to active Pt species improves catalyst's surface electron density, thus modulating the chemical adsorption of these small molecules. The engineered 0.1Pt/MoC with Pt SAs shows an outstanding FA dehydrogenation efficiency, with ca. 100% FA conversion and an initial TOF of up to 7739 h−1 at 25 °C. The versatile 0.1Pt/MoC also displays the ability for converting CO2 hydrogenation back to the hydrogen storage carrier FA (formate) with 88.3% yield under mild conditions. Moreover, in‐depth insights into the material microstructure, Pt−MoC electronic interactions, reaction‐dependent particle size effect, and adsorption energy are comprehensively investigated. [ABSTRACT FROM AUTHOR]

This study explores the synthesis of cyclopenta‐fused polyaromatic hydrocarbons (CP‐PAHs) via Pt‐catalyzed cyclization in water, focusing on the formation of fused pentagonal rings within heavily fused PAH frameworks. Utilizing platinum catalysts at lower temperatures (200‐260 °C) in water, led to the successful synthesis of singly cyclized CP‐PAHs. The reaction conditions facilitated the mono‐cyclization of substrates such as dibenzo[g,p]chrysene and its isomers, yielding the desired products while suppressing the formation of bis‐cyclized compounds. The use of Fe2O3 as an additive in conjunction with PtO2 was effective to suppress hydrogenation of the substrates and products. The products exhibited a redshift in UV‐visible absorption and photoluminescence bands due to a decrease in the HOMO−LUMO energy gap. These findings highlight the potential of Pt‐catalyzed cyclization for the controlled synthesis of CP‐PAHs, with implications for various applications in materials science. [ABSTRACT FROM AUTHOR]

Solar and wind energy for water electrolysis are gaining interest in contemporary times. In this context, platinum catalysts are commonly recognized as the standard for the hydrogen evolution reaction (HER), yet their effectiveness is constrained by their high cost and inadequate stability. Combining Ru and Ni lowers the material expense and greatly improves the electrocatalytic performance. Therefore, in the present study, a 3D nanostructured amorphous RuO2 aerogel is doped with various concentrations of Ni for enhanced HER activity. The results indicate that the 4% Ni‐RuO2 aerogel exhibits a 0D colloidal network featuring interconnected mesopores, with a high specific surface area of 241.5 m2·g−1. In addition, the 4% Ni‐RuO2 aerogel catalyst exhibits the lowest overpotentials of 63 and 122 mV at current densities of 10 and 50 mA·cm−2, respectively, along with enhanced hydrogen adsorption activity for the HER due to the 3D porous structure of the aerogel. However, a further increase in Ni doping leads to a decrease in HER activity due to a reduction in the number of catalytic Ru sites. The study found that doping with the optimum amount of Ni causes a redistribution of charges on the sample surface, thereby uncovering more reaction sites and enhancing the electrocatalytic performance. [ABSTRACT FROM AUTHOR]

UV-activated catalytic hydrosilation is a low-temperature crosslinking process that has attracted attention for its high efficiency and lower energy demand relative to thermal curing. In this study, formulations comprising industrially relevant model silanes and Pt photocatalysts trimethyl(methylcyclopentadienyl)platinum(IV) and trimethyl(pentamethylcyclopentadienyl)platinum(IV) (MeCpPtMe3 and Cp*PtMe3, respectively) were prepared with and without a photosensitizer (PS) and assessed for catalytic performance by a novel strategy. Photopolymerizations were initiated using different wavelengths from LEDs and monitored in real-time using an Attenuated Total Reflectance-Fourier Transform Infrared (ATR-FTIR) "well" strategy to track the degree of cure in ultra-thin films by consumption of hydride via the disappearance of the Si-H bending absorption band at 915 cm−1. Irradiation of formulations with 365 nm excitation showed higher conversions relative to 400 nm light and improvements to calculated initial reaction rates by incorporation of a PS suggested increased sensitization to 365 nm irradiation. To the best of our knowledge, this is the first study to report catalytic performance, electronic absorption spectroscopic data, and the crystal structure of Cp*PtMe3. [ABSTRACT FROM AUTHOR]

Search for a Platinum metal-free catalyst for Proton Exchange Membrane Fuel Cells (PEMFCs) is a concern to scientists as the Pt-catalyzed electrode comprises about 45% of the entire fuel cell stack cost. Due to layered structure, Two-dimensional (2D) MoS2 nanostructured materials have recently drawn attention as effective catalysts for oxygen reduction reaction (ORR). The 1T-phase of MoS2 (1T-MoS2) has higher electronic conductivity than the 2H-phase (2H-MoS2); high surface area 1T-MoS2 can have high electrocatalytic activity towards PEFFCs. Here, we report hydrothermally synthesized 2H-MoS2 and solvothermally synthesized mixed 1T/2H-MoS2 phases as a catalyst for ORR in PEM Fuel Cells. Owing to the high BET-specific surface area, hybrid 1T/2H-MoS2 showed better ORR activity than 2H-MoS2. The limiting current density of the 1T/2H-MoS2 hybrid structure is ‒7.1 mA cm−2 compared to Pt/C (‒8.2 mA cm−2) at 1600 rpm. The Tafel slope values of 2H-MoS2, 1T/2H-MoS2, and Pt/C are 92.7 mV dec−1, 57.5 mV dec−1, and 39.3 mV dec−1, respectively. The electron transferred during ORR are 3.8 and 1.8, respectively, for 1T/2H-MoS2 and 2H-MoS2 (in 0.1 M KOH) ; suggesting less formation of undesirable peroxide formation than 2H-MoS2. The 1T/2H-MoS2 displays better electrochemical durability compared to 2H-MoS2 (after 2000 CV cycles). [ABSTRACT FROM AUTHOR]

[Display omitted] • Pt-NiCoMnO 4 catalysts are firstly prepared for FA oxidation in air. • 1 %Pt-NiCoMnO 4 achieves 100 % FA conversion at RT (GHSV: 5,964 h−1). • FA is converted into CO 2 with diverse forms of intermediates, e.g., DOM and HCOO–. • FA and O 2 are adsorbed preferably on the Pt and nearby Ni sites, respectively. • Platinum-nickel sites offer favorable electronic structures for FA oxidation. Formaldehyde (FA), a carcinogenic oxygenated volatile organic compound, is present ubiquitously in indoor air. As such, it is generally regarded as a critical target for air quality management. The oxidative removal of FA under dark and room-temperature (RT) conditions is of practical significance. A series of ternary nickel–cobalt-manganese oxide–supported platinum catalysts (Pt/NiCoMnO 4) have been synthesized for FA oxidative removal at RT in the dark. Their RT conversion values for 50 ppm FA (X FA) at 5,964 h−1 gas hourly space velocity (GHSV) decrease in the following order: 1 wt% Pt/NiCoMnO 4 (100 %) > 0.5 wt% Pt/NiCoMnO 4 (25 %) > 0.05 wt% Pt/NiCoMnO 4 (14 %) > NiCoMnO 4 (6 %). The catalytic performance of 1 wt% Pt/NiCoMnO 4 has been examined further under the control of various process variables (e.g., catalyst mass, flow rate, relative humidity, FA concentration, time on stream, and molecular oxygen content). The catalytic oxidation of FA at low temperatures (e.g., RT and 60 °C) is accounted for by Langmuir–Hinshelwood mechanism (single-site competitive-adsorption), while Mars van Krevelen kinetics is prevalent at higher temperatures. In situ diffuse-reflectance infrared Fourier-transform spectroscopy reveals that FA oxidation proceeds through a series of reaction intermediates such as DOM, HCOO–, and CO 3 2–. Based on the density functional theory simulations, the unique electronic structures of the nearest surface atoms (platinum and nickel) are suggested to be responsible for the superior catalytic activity of Pt/NiCoMnO 4. [ABSTRACT FROM AUTHOR]

Carbon shell encapsulation has emerged as an effective strategy for enhancing the durability of Pt-based electrocatalysts for polymer electrolyte membrane fuel cells (PEFCs). Here, a nitrogen-doped carbon shell-encapsulated Pt catalyst supported on Ketjen black (Pt@C/KB) was synthesized, and its catalytic performance was characterized. The oxygen reduction reaction (ORR) performance and anti-poisoning properties were investigated in 0.1 M HClO 4 with and without H 2 SO 4 or H 3 PO 4 poisoning, using a rotating ring-disk electrode (RRDE) technique. Despite a decrease in the electrochemical surface area (ECSA), Pt@C/KB encapsulated by a thin graphene-like carbon shell (<1 nm thick) showed high selectivity for the four-electron reaction due to its superior anti-poisoning properties, as well as improved ORR activity and durability. The H 2 O 2 yield of Pt@C/KB, the precursor of hydroxyl radicals, was decreased approximately one third compared to bare Pt catalyst and the gap was more pronounced in the low potential (E ≤ 0.1 V/RHE) where close to practical anode potential, suggesting that Pt@C/KB can be applied as a new anode catalyst. Applying carbon core-shell catalysts to both the cathode and anode is a prospectively effective approach for improving the cell performance by improving the ORR activity and anti-poisoning properties, as well as for extending the lifespan of PEFCs. • Carbon shell mitigate the degradation of ORR performance by anion poisoning without blocking ORR active sites. • Carbon shell imparts anti-poisoning property to Pt catalyst against H 2 SO 4 or H 3 PO 4 poisoning. • Carbon shell encapsulation contributes low H 2 O 2 yield at PEFC anode potential region. • Application of the carbon core-shell catalyst to both the anode and cathode may be effective to expand lifespan of PEFC. [ABSTRACT FROM AUTHOR]

Platinum catalysts are widely used in electrocatalytic water splitting for the hydrogen evolution reaction and in hydrogen fuel cells for the oxygen reduction. Nonetheless, the practical use of the noble metal platinum in commercial applications faces significant challenges due to its exorbitant cost and the intricate nature of its synthetic methods. In this work, nitrogen-doped carbon layers covering platinum particles (Pt@NCL) are uniformly distributed on carbon nanofiber (CNF) substrates to synthesize heterojunction catalysts (Pt@NCL-CNF). Multiple characterization methods reveal that the nanoscale ultra-thin carbon layer successfully activates platinum nanoparticles and creates a tremendous accumulation of valence electrons at the interface of the heterojunction catalysts. Furthermore, the greater the number of defects produced in the ultra-thin carbon layer of Pt@NCL-CNF during the reaction, the more active sites are exposed. Therefore, Pt@NCL- CNF exhibits much better hydrogen evolution reaction and oxygen reduction reaction performance in pH-universal electrolytes than the commercial carbon-supported platinum (Pt/C) catalyst. This study elucidates the reaction mechanism, highlighting the crucial role of the ultra-thin carbon layer within the catalyst, and also confirms the catalyst performance in device applications. The proposed method can provide a simple and feasible mass-produced approach for the preparation and application of high performance low platinum catalyst. A heterogeneous bifunctional catalyst (Pt@NCL-CNF) is engineered with a core-shell architecture, incorporating a Platinum core ensconced within an ultra-thin carbon shell, all mounted on supportive carbon nanofibers. [Display omitted] • Pt@NCL-CNF catalysts have better PH-universal HER/ORR performance than commercial Pt/C. • Illustrate the reaction mechanism for Pt@NCL-CNF heterojunction. • Reveal the interface electronic interaction and ultra-thin carbon surface formative defects. • Confirm the feasible route of ultra-thin carbon layer covering Pt-based catalysts. • Validation of the application potential of Pt@NCL-CNF in devices. [ABSTRACT FROM AUTHOR]

Herein, we present catalyst‐regulated switchable site‐selective hydrosilylation of enynes, which are suitable for a wide range of alkyl and aryl substituted polar enynes and exhibit excellent functional group compatibility. Under the optimized conditions, silyl groups can be precisely installed at various positions of 1,3‐dienes. While α‐ and γ‐silylation products were obtained under platinum‐catalytic systems, β‐silylation products were delivered with [Cp*RuCl]4 as catalyst. This process lead to the formation of 1,3‐dienoates with diverse substitutions, which would pose challenges with other methodologies. [ABSTRACT FROM AUTHOR]

The synthesis, characterization and photocatalytic hydrogen evolution reaction (HER) performance of a series of metal–organic gels (MOGs) constructed from titanium(IV)-oxo clusters and dicarboxylato linkers (benzene-1,4-dicarboxylato and 2-aminobenzene-1,4-dicarboxylato) are described. All the MOGs exhibit a microstructure comprised of metal–organic nanoparticles intertwined into a highly meso-/macroporous structure, as demonstrated by cryogenic transmission electron microscopy and gas adsorption isotherms. Comprehensive chemical characterization enabled the estimation of the complex formula for these defective materials, which exhibit low crystallinity and linker vacancies. To gain deeper insights into the local structure, X-ray absorption fine structure (XAFS) spectroscopy experiments were performed and compared to that of the analogous crystalline metal–organic framework. Additionally, the ultraviolet–visible absorption properties and optical band gaps were determined from diffuse reflectance spectroscopy data. The MOGs were studied as light absorbers for the sacrificial photocatalytic HER under simulated solar light irradiation using a platinum co-catalyst by either (1) in situ photodeposition or (2) ex situ doping process, through a post-synthetic metalation of the MOG structure. The chemical analysis of the metalation, along with high-angle annular dark-field scanning transmission electron microscopy, revealed that although the in situ addition of the co-catalyst led to greater HER rates (227 vs. 110 μmolH2 gMOG−1 h−1 for in situ and ex situ, respectively), the ex situ modification provided a finer distribution of platinum nanoparticles along the porous microstructure and, as a result, it led to a more efficient utilization of the co-catalyst (45 vs. 110 mmolH2 gPt−1 h−1). [ABSTRACT FROM AUTHOR]

Proton exchange membrane fuel cells (PEMFCs) and alkaline membrane fuel cells (AEMFCs) have received great attention as energy devices of the next generation. Accelerating oxygen reduction reaction (ORR) kinetics is the key to improve PEMFC and AEMFC performance. Platinum‐based catalysts are the most widely used catalysts for the ORR, but their high price and low abundance limit the commercialization of fuel cells. Non‐noble metal‐nitrogen‐carbon (M−N−C) is considered to be the most likely material class to replace Pt‐based catalysts, among which Fe−N−C and Co−N−C have been widely studied due to their excellent intrinsic ORR performance and have made great progress in the past decades. With the improvement of synthesis technology and a deeper understanding of the ORR mechanism, some reported Fe−N−C and Co−N−C catalysts have shown excellent ORR activity close to that of commercial Pt/C catalysts. Inspired by the progress, regulation strategies for Fe−N−C and Co−N−C catalysts are summarized in this Review from 5 perspectives: (1) coordinated atoms, (2) environmental heteroatoms and defects, (3) dual‐metal active sites, (4) metal‐based particle promoters, and (5) curved carbon layers. We also make suggestions on some challenges facing Fe−N−C and Co−N−C research. [ABSTRACT FROM AUTHOR]

For di-nitroaromatics hydrogenation, it is a challenge to achieve the multi-step hydrogenation with high activity and selectivity due to the complexity of the process involving two nitro groups. Consequently, many precious metal catalysts suffer from low activity for this multi-step hydrogenation reaction. Herein, we employ a fully exposed Pt clusters catalyst consisting of an average of four Pt atoms on nanodiamond@graphene (Ptn/ND@G), demonstrating excellent catalytic performance for the multi-step hydrogenation of 2,4-dinitrotoluene. The TOF (40647 h−1) of Ptn/ND@G is significantly superior to that of single Pt atoms catalyst, Pt nanoparticles catalyst, and even all the known catalysts. Density functional theory calculations and absorption experiments reveal that the synergetic interaction between the multiple active sites of Ptn/ND@G facilitate the co-adsorption/activation of reactants and H2, as well as the desorption of intermediates/products, which is the key for the higher catalytic activity than single Pt atoms catalyst and Pt nanoparticles catalyst. Hydrogenating di-nitroaromatics with high activity and selectivity is challenging due to the process's complexity. Here the authors present a fully exposed Pt clusters catalyst for 2,4-dinitrotoluene hydrogenation, suggesting that the synergy between multiple active sites and moderate adsorption behavior is crucial for the high catalytic activity. [ABSTRACT FROM AUTHOR]

Metal–support interaction plays a critical role in determining the eventual catalytic activity of metals loaded on supporting substrates. This interaction can sometimes cause a significant drop in the metallic property of the loaded metal and, hence, a drop in catalytic activity in the reactions, especially in those for which low charge carrier transfer resistance is a necessary parameter. Therefore, there should be a case-by-case experimental or theoretical (or both) in-depth investigation to understand the role of support on each metal. Here, onto a layered porous carbon nitride (g-CN), we grew single crystalline Pt nanodisks (Pt@g-CN) with a lateral average size of 21 nm, followed by various characterisations such as electron microscopy techniques, and the measurement of electrocatalytic activity in the O2 reduction reaction (ORR). We found that intercalating Pt nanodisks in the g-CN interlayers causes an increase in electrocatalytic activity. We investigated the bonding mechanism between carbon support and platinum using density functional theory and applied the d-band theory to understand the catalytic performance. Analysis of Pt's density of states and electronic population across layers sheds light on the catalytic behaviour of Pt nanoparticles, particularly in relation to their thickness and proximity to the g-CN support interface. Our simulation reveals an optimum thickness of ~11 Å, under which the catalytic performance deteriorates. [ABSTRACT FROM AUTHOR]

The development of effective and stable electrocatalysts for the hydrogen evolution reaction (HER) in acidic electrolytes is a significant challenge. In this work, homogeneous Pt nanodendrites (Pt NDs) with a PtIr shell were successfully synthesized by a two-step wet chemical method. This open three-dimensional (3D) dendritic structure exhibited exceptional electrocatalytic characteristics, exposing as many active sites as feasible. Furthermore, by alloying Ir with Pt on the surface, catalytic activity was greatly enhanced while ensuring extremely high stability. Iridium surface-enriched platinum nanodendritic catalysts (Pt@PtIr NDs) outperformed the control samples and the commercial catalysts. In acidic HER test, Pt@PtIr NDs had a lower overpotential (22 mV) than Pt NDs (26 mV) and commercial Pt/C (31 mV) at 10 mA/cm2, and the activity of Pt@PtIr NDs remained consistent even after undergoing a continuous durability test for at least 168 h, which was much superior to the performance of commercial Pt/C (10 h) under identical test conditions. This study revealed that the application of 3D Pt dendritic metal alloys may offer a chance for the development of enhanced electrocatalysts in acidic HER. [ABSTRACT FROM AUTHOR]

Owing to good chemical stability, high catalytic activity and selectivity for target products as well as long service life, platinum alloy gauzes are irreplaceable catalysts for the synthesis of nitric acid, hydrocyanic acid and other chemicals via the ammonia oxidation process. In this paper, the preparation and processing of platinum alloy catalyst gauzes were briefly summarized from alloying to knitting. And then the mechanism of ammonia oxidation involved in the production of nitric acid and hydrocyanic acid was explored and the recent progress in the reaction-induced surface reconstruction was also introduced. Finally, the future development trends for the catalyst gauzes and ammonia oxidation method were proposed. [ABSTRACT FROM AUTHOR]

Exploring advanced platinum (Pt)-based electrocatalysts is vital for the widespread implementation of proton exchange membrane fuel cells (PEMFCs). Morphology control represents an effective strategy to optimize the behavior of Pt catalysts. In this work, an attempt is made to comprehensively review the effect of morphology control on the catalytic behavior of catalysts in the oxygen reduction reaction (ORR). First, the fundamental physicochemical changes behind morphology control, including exposing more active sites, generating appropriate lattice strains, and forming different crystalline surfaces, are highlighted. Then, recently developed strategies for tuning the morphologies of electrocatalysts, including core-shell structures, hollow structures, nanocages, nanowires, and nanosheets, are comprehensively summarized. Finally, an outlook on the future development of morphology control of Pt catalysts is presented, including rational design strategies, advanced in situ characterization techniques, novel artificial intelligence, and mechanical learning. This work is intended to provide valuable insights into designing the morphology and technological innovation of efficient redox electrocatalysts in fuel cells. [ABSTRACT FROM AUTHOR]

The quest for efficient hydrogen production via electrochemical water splitting has led to extensive research on catalytic materials. This work focuses on enhancing the catalytic functionality of metal-organic frameworks (MOFs) by incorporating platinum (Pt) to improve the performance of the hydrogen evolution reaction (HER). Fe-based MOFs mixed with platinum precursors were altered through laser treatment, which caused considerable changes in their structure and catalytic activity in just 3 min. This was achieved without the need for vacuum or an inert atmosphere. Characterization techniques including X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, and electrochemical measurements were used to characterize the synthesized materials. The laser-treated Pt–Fe MOF demonstrated outstanding HER performance with 3.5 wt% Pt content, outperforming commercial 20 wt% Pt/C catalysts, and exhibiting good stability even after prolonged cycling. These results highlight the potential of laser-treated MOFs for efficient and cost-effective electrochemical hydrogen generation. • The catalytic activity of MOFs incorporating Pt improved for HER. • The laser-treated Pt–Fe MOF contained 3.5 wt% Pt content. • 3 min of short laser irradiation for catalyst anchoring. [ABSTRACT FROM AUTHOR]

Iron‐nitrogen‐carbon (Fe‐N‐C) single‐atom catalysts are promising sustainable alternatives to the costly and scarce platinum (Pt) to catalyze the oxygen reduction reactions (ORR) at the cathode of proton exchange membrane fuel cells (PEMFCs). However, Fe‐N‐C cathodes for PEMFC are made thicker than Pt/C ones, in order to compensate for the lower intrinsic ORR activity and site density of Fe‐N‐C materials. The thick electrodes are bound with mass transport issues that limit their performance at high current densities, especially in H2/air PEMFCs. Practical Fe‐N‐C electrodes must combine high intrinsic ORR activity, high site density, and fast mass transport. Herein, it has achieved an improved combination of these properties with a Fe‐N‐C catalyst prepared via a two‐step synthesis approach, constructing first a porous zinc‐nitrogen‐carbon (Zn‐N‐C) substrate, followed by transmetallating Zn by Fe via chemical vapor deposition. A cathode comprising this Fe‐N‐C catalyst has exhibited a maximum power density of 0.53 W cm−2 in H2/air PEMFC at 80 °C. The improved power density is associated with the hierarchical porosity of the Zn‐N‐C substrate of this work, which is achieved by epitaxial growth of ZIF‐8 onto g‐C3N4, leading to a micro‐mesoporous substrate. [ABSTRACT FROM AUTHOR]