Intermetallic Nanoparticles Research Articles

Evolution of Ductile L12 Phase in (FeCoNi)86-Al7Ti7 High-Entropy Alloy Aging at Various Temperatures and Its Strengthening Mechanism

Ductile participation with small lattice misfit against matrix has been a long-sought-after character in toughening alloys, and recently multicomponent intermetallic nanoparticle L12 phase was explored by compositional modification in FeCoNi-based alloys and reported its benefits on strength and ductility through 780 °C for 4h aging treatment. However, the L12 (A3B: Ni3Al) evolution in (FeCoNi)86-Al7Ti7 at a wide range of aging temperatures still lacks of comprehensive investigations. Herein, a series of aging temperatures (580 °C, 650 °C, 690 °C, 720 °C, 780 °C, and 820 °C) were carried out based on the synchrotron in-situ variable temperature XRD of the alloy. Results showed that both the composition and morphology of the L12 phase are dramatically dependent on the aging temperatures. Specifically, with aging temperature increased from 580 °C to 820 °C, A sites preferentially incorporated by more Co and Fe gradually turn into B sites partially substituted by Fe and Ti in the L12 phase, together with its morphology transforming from spherical to cuboidal. Meanwhile, the hierarchical microstructure induced by the precipitates of the tiny L12 phase at the aging temperature of 780 °C compensated the size departure of the primary L12 phase against the critical size to enhance the strength by enhancing its dislocation storage capacity. These hierarchical L12 phases strengthen the strong pair-coupling mechanism, ultimately illustrating its excellent strength-ductility balance aging at 780 °C against other aging temperatures.

The Formation of γ-Valerolactone from Renewable Levulinic Acid over Ni-Cu Fly Ash Zeolite Catalysts.

Zeolites with different structures (P1, sodalite, and X) were synthesized from coal fly ash by applying ultrasonically assisted hydrothermal and fusion-hydrothermal synthesis. Bimetallic catalysts, containing 5 wt.% Ni and 2.5 wt.% Cu, supported on the zeolites, were prepared by a post-synthesis incipient wetness impregnation method. The catalysts were characterized by X-ray powder diffraction (XRPD), N2 physisorption, transmission electron microscopy (TEM), Mössbauer and X-ray photoelectron spectroscopies (XPS), and H2-temperature-programmed reduction (H2-TPR) analyses. The XRPD results showed that crystalline Cu0 and NixCuy intermetallic nanoparticles were formed in the reduced catalysts. The presence of the intermetallic phase affected the reducibility of the nickel by shifting it to a lower temperature, as confirmed by the H2-TPR curves. Based on the Mössbauer spectroscopic results, it was established that the iron contamination of the coal fly ash zeolites (CFAZs) was distributed in ionic positions of the zeolite lattice and as a finely dispersed iron oxide phase on the external surface of the supports. The formation of the NiFe alloy, not detectable by XRPD, was also evidenced on the impregnated samples. The catalysts were studied in the upgrading of levulinic acid (LA), derived from lignocellulosic biomass, to γ-valerolactone (GVL), in a batch reactor under 30 bar H2 pressure at 150 and 200 °C, applying water as a solvent. The NiCu/SOD and NiCu/X catalysts showed total LA conversion and a high GVL yield (>75%) at a reaction temperature of 200 °C. It was found that the textural parameters of the catalysts have less influence on the catalytic activity, but rather the stable dispersion of metals during the reaction. The characterization of the spent catalyst found the rearrangement of the support structure. The high LA conversion and GVL yield can be attributed to the weak acidic character of the support and the moderate hydrogenation activity of the Ni-Cu sites with high dispersion.

Seed-Mediated Synthesis of High Loading PtCo Intermetallic Compounds Enhanced Catalytic Efficacy and Long-Term Stability for Oxygen Reduction Reaction.

Atomically ordered intermetallic Pt-based nanoparticles, recognized as advanced electrocatalysts, exhibit superior activity for the oxygen reduction reaction (ORR) in fuel cell cathodes. Nevertheless, the formation of these ordered structures typically necessitates elevated annealing temperatures, which can accelerate particle growth and diminished reactivity. In this study, we synthesized carbon-supported platinum-cobalt intermetallic compounds (PtCo-IMCs) with sub-4 nm particle sizes and uniform distribution. These catalysts, characterized by high platinum content and exceptional ORR activity, are specifically tailored for heavy-duty vehicle (HDV) applications. The PtCo-IMCs exhibited significantly enhanced catalytic performance and durability compared to conventional Pt-based catalysts, utilizing platinum nanoparticles as nucleation sites to promote growth. This method effectively retained smaller particle sizes while achieving a higher degree of ordering and alloying during high-temperature annealing. Optimization of the annealing temperature resulted in peak activity and stability at 800 °C. The mass activity (MA) of the PtCo-800 catalyst was 2.7-fold and 1.8-fold that of the commercial Pt/C and disordered PtCo catalysts, respectively. Additionally, the single cell employing the PtCo-800 catalyst showed a minimal voltage loss of only 27 mV at a current density of 2 A cm-2 after 30,000 cycles of the accelerated durability test (ADT), underscoring its long-term stability.

Integrated Catalyst ZnNC⊂PtZn for High‐performance Ethanol Electrooxidation and DEFC

We report here an electrocatalyst that exhibits superior performance in the electrooxidation of ethanol. The reactive centers of the catalyst have a nest‐type configuration with outer Zn‐NxC nest covering inner PtZn intermetallic compound nanoparticle loaded on carbon support (ZnNC⊂PtZn/C). The high‐energy stepped facets of the inner PtZn nanoparticle confined and shaped by the outer Zn‐NxC nest is highly active for the critical C‐C bond cleavage of ethanol in oxidation, confirmed by experimental characterizations and density functional theory calculations. The catalyst shows a rare high‐performance and demonstrates a mass activity of 3.7 A mgPt‐1 and a Faradaic efficiency of 78.2%, following the C1 pathway of reaction and the retention of initial activity remains 97% after 5,000 cycles. The unique configuration, also mitigating the concentration polarization, endows the catalyst with innate ethanol electrooxidation property by inner‐outer synergic interactions, leading to unexpected power output of an acidic direct ethanol fuel cell.

Integrated Catalyst ZnNC⊂PtZn for High-Performance Ethanol Electrooxidation and DEFC.

We report here an electrocatalyst that exhibits superior performance in the electrooxidation of ethanol. The reactive centers of the catalyst have a nest-type configuration with outer Zn-NxC nest covering inner PtZn intermetallic compound nanoparticles loaded on carbon support (ZnNC⊂PtZn/C). The high-energy stepped facets of the inner PtZn nanoparticles confined and shaped by the outer Zn-NxC nest is highly active for the critical C-C bond cleavage of ethanol in oxidation, confirmed by experimental characterizations and density functional theory calculations. The catalyst shows a rare high-performance and demonstrates a mass activity of 3.7 A mgPt -1 and a Faradaic efficiency of 78.2 %, following the C1 pathway of reaction and the retention of initial activity remains 97 % after 5,000 cycles. The unique configuration, also mitigating the concentration polarization, endows the catalyst with innate ethanol electrooxidation property by inner-outer synergic interactions, leading to unexpected power output of an acidic direct ethanol fuel cell.

High-Loading Intermetallic PtCo Nanoparticles Supported on S-Doped Carbon for Oxygen Reduction Reaction Catalysts

Improving catalysts for the oxygen reduction reaction (ORR) is crucial for commercialization of proton exchange membrane fuel cells (PEMFCs) due to the sluggish kinetics of ORR at the cathode. Current ORR catalysts face challenges such as high costs associated with precious metals and poor durability. A common approach to improve catalyst activity is to alloy Pt with transition metals, such as cobalt and nickel, to control the d-band center. Instead of the disordered PtM, Pt intermetallic compounds show improved ORR intrinsic activity and enhanced stability. Also, doping carbon supports with heteroatoms such as nitrogen and sulfur is a feasible strategy to enhance the interaction between the metal nanoparticles of the catalyst and its support, which leads to improved performance and stability of the catalysts.In this study, we synthesized high-loading intermetallic PtCo nanoparticles supported on sulfur-doped carbon. High metal loading catalysts have significant advantages for practical PEMFC applications as they accelerate mass transport, leading to a reduction in voltage loss, especially under high current densities. To synthesize high-loading intermetallic PtCo nanoparticles, uniform sulfur doping on commercial carbon support is introduced, since sulfur sites can anchor metal nanoparticles even during a harsh heat treatment process. The sulfur sites not only minimize sintering, but also improve the electrochemical performance. Using this approach, high-loading (52.5 wt%) sub-5 nm PtCo intermetallic compounds with a Pt-rich shell (PtCo@Pt/S-BP) were successfully synthesized. The morphology and characteristics of the PtCo nanoparticles were confirmed through various techniques, including XRD, TEM, ICP-OES, HAADF-STEM, EDS mapping, and XPS analysis. In the half-cell test, PtCo@Pt/S-BP exhibited over 5-fold enhancement in mass activity and 6-fold increase in specific activity compared to commercial Pt/C. Additionally, the performance of PtCo@Pt/S-BP was maintained even after 50,000 cycles due to thermodynamically stable structure of the intermetallic phase and Pt-rich shell. This synthesis strategy provides a promising pathway for practical application of Pt-based catalysts in future PEMFCs.

Crystallography of Intermetallic Pt Nanoparticle Catalysts on Engineered Carbon Supports

Platinum-based electrocatalysts represent the state-of-the-art for many fuel cell and electrolyzer applications due to their relatively high activity for both the hydrogen oxidation reaction (HOR) and the oxygen reduction reaction (ORR). Due to the high cost of Pt metal, Pt utilization is maximized by dispersing the Pt on a carbon support as nanoparticles, but further improvements to catalyst activity and durability, as well as further cost reductions, are required for commercialization of fuel cell and electrolyzer technologies. Essential to the improvement of such catalysts is the design and preparation of Pt-based crystalline nanostructures, which can enhance the activity and durability of an electrocatalyst without increasing Pt loading. Furthermore, by alloying Pt with other, more earth-abundant transition metals, ordered intermetallic nanoparticles can be prepared which display not only enhanced electrocatalytic properties, but also require less of the expensive Pt metal for fabrication. Here, we crystallographically describe various intermetallic Pt catalysts supported on a new class of carbon materials developed by Pajarito Powder known as the Engineered Catalyst Support (ECS). ECS materials can disperse up to 50% Pt by weight of the catalyst by virtue of the high support surface area (400-900 m2/g), ideal for structural study by bulk crystallographic methods. Through correlation of crystalline Pt structures with electrochemical performance data, structure/function relationships are established to inform the high performance of Pt/ECS catalysts.

Atomic Ordering Promoted L10-Zn-PtCo Intermetallic Nanocatalysts for Enhanced Oxygen Reduction Reaction in PEMFCs

The sluggish oxygen reduction reaction (ORR) kinetics has inhibited the widespread commercialization of polymer electrolyte membrane fuel cells (PEMFCs). Therefore, there has been a great need for catalysts that promote the ORR. PtCo intermetallic nanoparticles supported on conductive carbon, which have superior activity and durability toward the ORR, have been considered promising catalysts for the cathode in PEMFCs. In general, high-temperature annealing is required to synthesize intermetallic catalysts, which accompanies the sintering of the nanoparticles, leading to a decrease in electrochemical active surface area (ECSA). Therefore, a sophisticated strategy is required to enhance the ordering degree of PtCo intermetallic compound nanoparticles without making the annealing process extreme. Here, we present L10-Zn-PtCo intermetallic nanocatalysts (Zn-PtCo/Zn-NC) in which the Zn incorporation strategy enhances the ordering degree. Computational calculation using machine learning force field (MLFF) elucidates that introducing Zn atoms can promote diffusion kinetics within the crystal structure of PtCo. X-ray diffraction (XRD) patterns and extended X-ray absorption fine structure (EXAFS) quantitatively confirm the enhancement of the ordering degree due to incorporating Zn atoms. In the half-cell configuration, the synthesized Zn-PtCo/Zn-NC catalyst shows an initial mass activity of 1.76 A mgPt -1 at 0.9 VRHE. In addition, it maintains 93.8% of its initial ECSA after the accelerated durability test (ADT). In H2-Air fuel cells, the Zn-PtCo/Zn-NC cathode achieves a high peak power density of 0.64 W cm-2, compared to that of the Pt/C (0.50 W cm-2), even with a low Pt usage of 0.05 mgPt cm-2 at the cathode.

Pt Ternary Alloy with Rare Earth Metal - Pt5Ce-Co Intermetallic Nanoparticles as Highly Active Catalyst for Oxygen Reduction Reaction in PEMFCs

Platinum-based alloy catalysts have been extensively studied for oxygen reduction reaction (ORR) in polymer electrolyte membrane fuel cells (PEMFCs) because their superior enhancement in activity and durability. Alloying with rare earth (RE) elements is an important direction of exploring in Pt-based alloy design, due to its electronic configurations that can provide additional pathways for tailoring the electronic structures of active elements through alloying. Pt-RE alloys show more negative formation enthalpy than the widely applied late transition metal-based Pt alloys, which makes them thermodynamically and kinetically stable. The recently developed solid-phase synthesis strategy makes the nanoscale RE-based alloys more applicable. Here we reported a ternary intermetallic alloy of Pt5CeCo/C synthesized by two step-reduction method, annealing in diluted H2 under high temperature. Due to the unique 4f orbital of Lanthanoids Ce and the contraction effect, the electronic valence state of Pt alloys was modified, thus, optimizing the adsorption energy of the the reaction intermediates over the catalyst active sites, and effectively improving the electrocatalytic performance of the catalysts. It appears that the introduction of Ce greatly improves the ORR activity and fuel cell performance of Pt5CeCo/C, which achieved 2.8 A∙mgPt -1 of mass activity and 78.1 m2∙gPt -1 of ECSA using rotating disk electrode (RDE), while it is only 0.62 A∙mgPt -1 and 75.2 m2∙gPt -1 for Pt3Co/C, respectively. After 30k of accelerated stress test (AST) on RDE, Pt5CeCo/C can maintain 1.4 A∙mgPt -1 of mass activity, far exceeding Pt3Co/C and commercial Pt/C. For membrane electrode assembly (MEA) test, Pt5CeCo/C shows an initial mass activity of 724 mA∙mgPt -1, and a current density of 1876 mA∙cm-2 at 0.7 V under heavy-duty vehicle (HDV) testing conditions, while it still remains 1400 mA∙cm-2 at 0.7 V after 30k AST. This work provides an avenue to design advanced PGM ternary alloys by incorporating rare-earth metals to promote the catalyst performance.

Tandem Upgrading of Bio-Furans to Benzene, Toluene, and p-xylene by Pt1Sn1 Intermetallic Coupling Ordered Mesoporous SnO2 Catalyst.

Benzene, toluene, and p-xylene (BTpX) are among the most important commodity chemicals, but their productions still heavily rely on fossil resources and thus pose serious environmental burdens and energy crisis. Herein, the tandem upgrading of bio-furans is reported to high-yield BTpX by rationally constructing a versatile Pt1Sn1 intermetallic coupling ordered-mesoporous SnO2 (OM-SnO2) catalyst. It is shown that with increasing reduction temperature from 200 to 350°C, Pt nanoparticles (NPs) are first formed on OM-SnO2, then converted to Pt3Sn1 intermetallic nanoparticles (iNPs), and finally to Pt1Sn1 iNPs with a gradually-thickened SnO2 overlayer. Impressively, the Pt1Sn1 iNPs and defect-rich OM-SnO2 in the optimized Pt@OM-SnO2 can serve as the highly-active species for the hydrogenolysis of 5-hydroxymethylfuran to 2,5-dimethylfuran and the aromatization of 2,5-dimethylfuran with acrylic acid to p-xylene, affording the highest yields of 99.1% and 96.1%, respectively. More importantly, it can perfectly realize the tandem upgrading of furan, furfural and 5-hydroxymethylfuran to benzene, toluene and p-xylene with high yields of 94.6%, 94.2% and 95.2%, respectively, representing a new tandem catalytic system to realize the high-yield BTpX productions from their corresponding bio-furans. This catalyst also shows good recyclability and excellent scalability, which together with its superior activity/selectivity suggest a high potential for sustainable BTpX productions.

Non‐Oxidative Dehydroaromatization of Linear Alkanes on Intermetallic Nanoparticles

AbstractThere has been significant interest in developing new catalytic systems to convert linear chain alkanes into olefins and aromatics. In the case of higher alkanes (≥C6), the production of aromatic compounds such as benzene‐toluene‐xylenes is highly desirable. However, as the length of the carbon chain increases, the dehydrogenation process becomes more complex, not only due to the challenges of C−H activation but also the need for selectivity towards the desired products by the possibility of side reactions such as isomerization and cracking. Here, we present a detailed analysis of the dehydroaromatization of n‐hexane, n‐heptane, and n‐octane, using PtSn intermetallic nanoparticles supported on SBA‐15 as the catalyst. Through in situ spectroscopic and kinetic analysis, we have probed the reaction kinetics and catalyst deactivation, and provided a mechanistic understanding of the dehydroaromatization process on the surface of the PtSn intermetallic nanoparticles. Introducing Sn has been shown to be crucial not only for enhancement of catalytic activity, but also for higher aromatics selectivity and stability on stream. Furthermore, the analysis of dehydroaromatization reaction rates of reactant and possible intermediates indicates that the dehydroaromatization of n‐hexane to benzene likely proceeds through initial dehydrogenation steps followed by ring closing.

Oxygen Vacancy-Mediated Synthesis of Inter-Atomically Ordered Ultrafine Pt-Alloy Nanoparticles for Enhanced Fuel Cell Performance.

Pt-based intermetallics are expected to be the highly active catalysts for oxygen reduction reaction (ORR) in proton-exchange membrane fuel cells but still face great challenges in controllable synthesis of interatomically ordered and ultrafine intermetallic nanoparticles. Here, we propose an oxygen vacancy-mediated atomic diffusion strategy by mechanical alloying to reduce the energy barrier of the transition from interatomic disordering to ordering, and to resist interparticulate sintering via strong M-O-C bonding. This synthesis results in a nanosized core/shell structure featuring an interatomically ordered PtM core and a Pt shell of two to three atomic layers in thickness and can be extended to the multicomponent PtM (M = Co, FeCo, FeCoNi, FeCoNiGa) systems. The electron enrichment in the Pt outer shell induced by the compressive strain leads to the enhanced antibonding orbital occupation below the Fermi level and accelerated OH* desorption kinetics. The optimized PtCo-O/C-6 catalyst presents excellent ORR activity (mass activity = 1.28 A mgPt-1 at 0.9 ViR-free, peak power densities = 2.38/1.25 W cm-2 in H2-O2/-air) and durability (∼1% activity loss in over 50 h in air condition) in fuel cells at a total Pt loading of 0.1 mgPt cm-2. Furthermore, we establish a systematic correlation to elucidate the formation mechanisms of highly ordered intermetallic catalysts underlying oxygen vacancies. This study provides a general approach for the large-scale production of highly ordered and nanosized Pt-dispersed intermetallic catalysts.

Refinement of eutectic structure and precipitates of Cu–20Ag alloy due to Y microalloying

Copper-silver alloy rod with high mechanical properties and stable conductivity are the key materials for the preparation of microfilaments used in endoscopy and other medical fields. In this paper, the microstructure of Cu–20Ag rod was regulated by adding trace rare earth Y in order to improve the comprehensive performance of copper-silver alloy further. and studies the distribution and existence of rare earth Y as well as the influence on the performance of copper-silver alloy rod billet. The results of research show that: rare earth Y mainly exists in the branching nodes of the eutectic organization, so that the alloy in the solidification of constitutional supercooling increases, thus refining the eutectic structure, and make it uniformly distributed. After addition of 0.01 wt%Y, Cu4Y was precipitated in the eutectic structure of the rod. After adding 0.03 wt%Y, the precipitates types increased to trace intermetallic compound AgY and nanoparticles Cu4Y. The increase of the interface between eutectic structure and Cu matrix decreases the electron scattering probability. This is the main factor to lead to the decrease of electrical conductivity. The precipitation hardening of precipitated phase and the increase of interface between eutectic structure and Cu matrix are the main factors for the increase of tensile strength of bar billet. The main factor of the decrease in the conductivity of rod billet is the increase of Ag phase dissolved in eutectic structure and the interface between eutectic structure and Cu matrix.

Pt3(CoNi) Ternary Intermetallic Nanoparticles Immobilized on N-Doped Carbon Derived from Zeolitic Imidazolate Frameworks for Oxygen Reduction.

Pt-based intermetallic compound (IMC) nanoparticles have been considered the most promising catalysts for oxygen reduction reaction (ORR) in proton exchange membrane fuel cells (PEMFC). Herein, we propose a strategy for producing ordered Pt3(CoNi) ternary IMC nanoparticles supported on N-doped carbon materials. Particularly, the Co and Ni are originally embedded into ZIF-derived carbon, which diffuse into Pt nanocrystals to form Pt3(CoNi) nanoparticles. Moreover, a thin layer of carbon develops outside of Pt3(CoNi) nanoparticles during the cooling process, which contributes to stabilizing the Pt3(CoNi) on carbon supports. The optimal Pt3(CoNi) nanoparticle catalyst has achieved significantly enhanced activity and stability, exhibiting a half-wave potential of 0.885 V vs reversible hydrogen electrode (RHE) and losing only 16 mV after 10,000 potential cycles between 0.6 and 1.0 V. Unlike the direct-use commercial carbon (VXC-72) for depositing Pt, we utilized ZIF-derived carbon containing dispersed Co and Ni nanocluster or nanoparticles to prepare ordered Pt3(CoNi) intermetallic catalysts.

Pt Ternary Alloy with Rare Earth Metal - Pt5Ce-Co Intermetallic Nanoparticles as Highly Active Catalyst for Oxygen Reduction Reaction in PEMFCs

Alloying with rare earth elements is an important direction of exploring in Pt-based alloy design in oxygen reduction reaction (ORR), due to its special electronic configurations. Here we reported a ternary intermetallic alloy Pt5Ce-Co/C. The electronic valence state of Pt alloys was modified by the unique 4f orbital and the contraction effect of Ce, plus the additional active sites provided by the Co incorporation, optimizing the adsorption energy of the reaction intermediates, and effectively improving the electrocatalytic performance. The Pt5Ce-Co/C achieved 2.8 A∙mgPt -1 of mass activity in ORR catalysis, which can maintain 1.4 A∙mgPt -1 after 30k of accelerated stress test (AST). For membrane electrode assembly test, Pt5Ce-Co/C shows an initial mass activity of 724 mA∙mgPt -1, and a current density of 1876 mA∙cm-2 at 0.7 V under heavy-duty vehicle testing. This work provides an avenue to design advanced PGM ternary alloys by incorporating rare-earth metals to promote the catalyst performance.

Stable and homogeneous intermetallic alloys by atomic gas-migration for propane dehydrogenation

Intermetallic nanoparticles (NPs) possess significant potentials for catalytic applications, yet their production presents challenges as achieving the disorder-to-order transition during the atom ordering process involves overcoming a kinetic energy barrier. Here, we demonstrate a robust approach utilizing atomic gas-migration for the in-situ synthesis of stable and homogeneous intermetallic alloys for propane dehydrogenation (PDH). This approach relies on the physical mixture of two separately supported metal species in one reactor. The synthesized platinum-zinc intermetallic catalysts demonstrate exceptional stability for 1300 h in continuous propane dehydrogenation under industrially relevant industrial conditions, with extending 95% propylene selectivity and propane conversions approaching thermodynamic equilibrium values at 550–600 oC. In situ characterizations and density functional theory/molecular dynamics simulation reveal Zn atoms adsorb on the particle surface and then diffuse inward, aiding in the formation of ultrasmall and highly ordered intermetallic alloys. This in-situ gas-migration strategy is applicable to a wide range of intermetallic systems.

Strong Electronic Metal-Support Interactions Enable the Increased Spin State of Co-N4 Active Sites and Performance for Acidic Oxygen Reduction Reaction.

Nonprecious metal catalysts, particularly M-N-C catalysts, are widely recognized as promising contenders for the oxygen reduction reaction (ORR). However, a notable performance gap persists between M-N-C catalysts and Pt-based catalysts under acidic conditions. In this study, hybrid catalysts comprising single Co atoms and ultralow concentrations of Pt3Co intermetallic nanoparticles (NPs) are introduced to enhance ORR performance. Under acidic conditions, these hybrid catalysts demonstrate ORR efficiency with a half-wave potential of 0.895 V, negligible decay even after 80 000 cycles, and a high maximum power density of 1.34 W cm-2 in fuel cells. This performance surpasses those of Co-N-C and Pt/Co-N-C catalysts. Both experimental findings and theoretical computations suggest that the heightened ORR activity stems from an increase in the spin density of Co sites induced by noble metal NPs, facilitating the activation of O-O bonds via side-on overlapping and enabling a transition in the reaction pathway from associative to dissociative processes. This research offers a promising avenue for the systematic design of M-N-C cathodes with an enhanced performance for acidic fuel cells.

Ternary ordered L10-Pt-Co-Fe intermetallics for efficient ORR catalysis through dissociation pathway

Developing efficient and durable Pt-based electrocatalysts for oxygen reduction reaction (ORR) is critical for the practical application of fuel cells but still remains challenge at present. Here we successfully synthesized a series of ternary L10-PtCoxFe1-x (x=0.33, 0.50 and 0.67) intermetallic nanoparticles (NPs) supported on reduced graphene oxide for ORR catalysis. L10-PtCo0.50Fe0.50 exhibits the highest mass activity (MA) of 0.93 A mg−1Pt at 0.9 V (1.82 times the corresponding binary L10-PtCo intermetallics) and minimal activity loss (24.73 % loss in MA) after 30,000 potential cycles. By Density Functional Theory calculations, the excellent performance of ternary L10-PtCo0.50Fe0.50 can be ascribed to: (1) more efficient electronic structure regulation caused by dual-element driven electron transfer, which leads to more electron accumulation on Pt and weakens the over-binding of oxygen-containing species, (2) the unique two-center bridge pattern of O2 adsorption over Pt-Fe site leads to ORR proceeding via. the dissociative mechanism, avoiding the formation of OOH*.

N-doped carbon confined ternary Pt2NiCo intermetallics for efficient oxygen reduction reaction

Developing high performance electrocatalysts for the cathodic oxygen reduction reaction (ORR) is essential for the widespread application of fuel cells. Herein, a promising Pt2NiCo atomic ordered ternary intermetallic compound with N-doped carbon layer coating (o-Pt2NiCo@NC) has been synthesized via a facile method and applied in acidic ORR. The confinement effect provided by the carbon layer not only inhibits the agglomeration and sintering of intermetallic nanoparticles during high temperature process but also provides adequate protection for the nanoparticles, mitigating the aggregation, detachment and poisoning of nanoparticles during the electrochemical process. As a result, the o-Pt2NiCo@NC demonstrates a mass activity (MA) and specific activity (SA) of 0.65 A/mgPt and 1.41 mA/cmPt2 in 0.1 mol/L HClO4, respectively. In addition, after 30,000 potential cycles from 0.6 V to 1.0 V, the MA of o-Pt2NiCo@NC shows much lower decrease than the disordered Pt2NiCo alloy and Pt/C. Even cycling at high potential cycles of 1.5 V for 10,000 cycles, the MA still retains ∼70%, demonstrating superior long-term durability. Furthermore, the o-Pt2NiCo@NC also exhibits strong tolerance to CO, SOx, and POx molecules in toxicity tolerance tests. The strategy in this work provides a novel insight for the development of ORR catalysts with high catalytic activity, durability and toxicity tolerance.

The impact of the porous structure on the efficiency of PdIn methanol synthesis catalysts

The characteristics of the porous structure and the specific surface area of the support have a significant impact on both the structure of the active sites and the efficiency of catalysts for the synthesis of methanol from CO2. The use of a complex of physicochemical methods of analysis in combination with the results of catalytic experiments has enabled the main tendencies in the development of productive and selective catalysts based on PdIn intermetallic nanoparticles to be established.