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Pt‐based intermetallics are recognized as effective catalysts for oxygen reduction reaction (ORR) in fuel cells. However, the synthesis of intermetallics often requires prolonged annealing and the effect of different crystal structures on ORR still need to be investigated. Herein, L12‐Pt3Mn and L10‐PtMn intermetallics with Pt‐skin are rapidly synthesized through an emerging periodic carbothermal shock method to investigate their ORR‐activity difference. The formation of L12‐Pt3Mn and L10‐PtMn can be well‐controlled by the Pt/Mn feeding ratio, pulse cycles, and temperature. Electrocatalytic investigations show that L12‐Pt3Mn presents a more positive half‐wave potential (0.91 V vs RHE) and onset potential (1.02 V vs RHE) than those of L10‐PtMn. The mass activity and specific activity of L12‐Pt3Mn are respectively fourfold and threefold greater than those of L10‐PtMn. Theoretical calculations indicate that the L12‐Pt3Mn has a more substantial work function than L10‐PtMn, thereby conferring L12‐Pt3Mn with an increased electron density allocation for catalytic involvement. This electron confinement imparts L12‐Pt3Mn with a Pt d‐band center lower than that of L10‐PtMn, consequently attenuating the adsorption of strongly bonded *O intermediates during the rate‐determining step. This study not only employs a straightforward method for intermetallic preparation but also elucidates the discrepancies in ORR activity across intermetallics with distinct structures. [ABSTRACT FROM AUTHOR]

Controllable synthesis of atomically ordered intermetallic nanoparticles (NPs) is crucial to obtain superior electrocatalytic performance for fuel cell reactions, but still remains arduous. Herein, we demonstrate a novel and general hydrogel‐freeze drying strategy for the synthesis of reduced graphene oxide (rGO) supported Pt3M (M=Mn, Cr, Fe, Co, etc.) intermetallic NPs (Pt3M/rGO‐HF) with ultrasmall particle size (about 3 nm) and dramatic monodispersity. The formation of hydrogel prevents the aggregation of graphene oxide and significantly promotes their excellent dispersion, while a freeze‐drying can retain the hydrogel derived three‐dimensionally (3D) porous structure and immobilize the metal precursors with defined atomic ratio on GO support during solvent sublimation, which is not afforded by traditional oven drying. The subsequent annealing process produces rGO supported ultrasmall ordered Pt3M intermetallic NPs (≈3 nm) due to confinement effect of 3D porous structure. Such Pt3M intermetallic NPs exhibit the smallest particle size among the reported ordered Pt‐based intermetallic catalysts. A detailed study of the synthesis of ordered intermetallic Pt3Mn/rGO catalyst is provided as an example of a generally applicable method. This study provides an economical and scalable route for the controlled synthesis of Pt‐based intermetallic catalysts, which can pave a way for the commercialization of fuel cell technologies. [ABSTRACT FROM AUTHOR]

Pt alloy nanostructures show great promise as electrocatalysts for the oxygen reduction reaction (ORR) in fuel cell cathodes. Herein, three-dimensional (3D) Pt-Pd-Co trimetallic network nanostructures (TNNs) with a high degree of alloying are synthesized through a room temperature wet chemical synthetic method by using K2PtCl4/K3Co(CN)6-K2PdCl4/K3Co(CN)6 mixed cyanogels as the reaction precursor in the absence of surfactants and templates. The size, morphology, and surface composition of the Pt-Pd-Co TNNs are investigated by scanning electron microscopy (SEM), transmission electron microscopy (TEM), selected-area electron diffraction (SAED), energy dispersive spectroscopy (EDS), EDS mapping, X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). The 3D backbone structure, solid nature, and trimetallic properties of the mixed cyanogels are responsible for the 3D structure and high degree of alloying of the as-prepared products. Compared with commercially available Pt black, the Pt-Pd-Co TNNs exhibit superior electrocatalytic activity and stability towards the ORR, which is ascribed to their unique 3D structure, low hydroxyl surface coverage and alloy properties. [ABSTRACT FROM AUTHOR]

The commercialization of fuel cell technologies requires a significant reduction in the amount of expensive platinum catalyst in the cathode while still maintaining high catalytic activity and stability. Herein a cost‐effective, highly durable, and efficient catalyst consisting of ordered Fe3Pt nanoparticles supported by mesoporous Ti0.5Cr0.5N (Fe3Pt/Ti0.5Cr0.5N) is demonstrated. The Fe3Pt/Ti0.5Cr0.5N catalyst exhibits a five‐fold increase in mass activity relative to a Pt/C catalyst at 0.9 V for the oxygen reduction reaction. More importantly, the catalyst shows a minimal loss of activity after 5000 potential cycles (9.7%). The enhanced activity of the ordered Fe3Pt/Ti0.5Cr0.5N catalyst, in combination with its enhanced stability, makes it very promising for the development of new cathode catalysts for fuel cells. An efficient and cost‐effective nitride‐supported, ordered Fe3Pt electro‐catalyst that exhibits significant enhancement in catalytic activity and durability for the oxygen reduction reaction (ORR) when compared to disordered Fe3Pt/C and Pt/C is demonstrated. [ABSTRACT FROM AUTHOR]

Nanocrystalline intermetallics in bulk with high surface area hold enormous promise as an efficient catalyst for real fuel cell applications due to their unique electrocatalytic properties. In this work, a novel three-dimensional (3D) porous Pd–Sn intermetallics in network nanostructures (Pd–Sn-INNs) has been fabricated at relatively low temperature for the first time by one-step ethylene glycol-assisted hydrothermal reduction method. The structure characteristics of the Pd–Sn-INNs are confirmed by scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy-dispersive X-ray (EDX), selected-area electron diffraction (SAED), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). The as-prepared 3D Pd–Sn-INNs exhibit remarkably improved electrocatalytic activity and stability towards formic acid oxidation reaction (FAOR) over commercially available Pd black. [ABSTRACT FROM AUTHOR]

Rational structure design, composition control and heteroatom doping are efficient strategies to achieve excellent electrocatalysts for the oxygen reduction reaction (ORR) in fuel cells or metal-air batteries. Herein, a facile and efficient approach to prepare ultrathin carbon nanosheet superstructure (BN/C) with high B, N-doping level by using sodium chloride (NaCl)-assisted pyrolysis method is proposed. The developed BN/C catalyst exhibits good catalytic activity for ORR in alkaline medium with a half-wave potential (E 1/2) of 0.8 V, which is comparable to that of commercial Pt/C. The BN/C catalyst also shows much better long-term stability and satisfactory tolerance for the methanol crossover effect. This excellent performance is attributed to the structure and composition characteristics of BN/C, including the large surface area (1085 m2 g−1), hierarchically porous structure, the synergistic effect of the B, N co-doping and high content of ORR active species. Significantly, the B element with electron-deficient property in BN/C can create more charged sites favorite for O 2 adsorption and thus accelerate reaction kinetics in ORR. Furthermore, a rechargeable Zn-air battery device comprising BN/C catalyst and RuO 2 with a liquid electrolyte shows superior performance with an open-circuit potential of ∼1.36 V, a peak power density of ∼115 mW cm−2, as well as excellent durability (1000 cycles for 14 days of operation). Moreover, a flexible solid-state Zn-air battery containing BN/C catalyst and RuO 2 shows good cycling durability under different bending states, indicating the excellent practicability in wearable devices. Image 1 [ABSTRACT FROM AUTHOR]

Carbon-supported metal nanoparticles are widely used as electrocatalysts in polymer electrolyte membrane fuel cells (PEMFCs), but still suffer from deactivation because of metal leaching and sintering at high temperature. Herein, we propose a novel and scalable metal coordination-polymer strategy for the facile synthesis of bimetallic PdFe nanoparticles embedded nitrogen-doped carbon (PdFe@N-C) nanoframes as a Mott-Schottky electrocatalyst to efficiently catalyze the oxygen reduction reaction (ORR) in PEMFCs. The metal coordination-polymer is formed through metal ions (Pd and Fe) mediated self-polymerization of 1-naphthylamine (NA), which allows alloy nanoparticles to bind tightly with N-carbon nanoframes after pyrolysis. It is found that PdFe nanoparticles with very small particle-size are uniformly embedded in the porous N-carbon nanoframes and physically separated from each other by the carbon matrix. Profited from the unique structure and composition merits, the half-wave potential of the developed PdFe@N-C nanoframes towards ORR is positively shifted by 30 and 50 mV compared to those of Pd@N-C and Pd/C, respectively. Importantly, the PdFe@N-C nanoframes derived acidic PEMFC delivers a high-power density of 0.91 W cm−2 together with remarkable operational stability after 10 h discharging. Such good performances make the metal-NA coordination-polymer an attractive precursor to design and synthesize high-performance electrocatalysts for fuel cells. Image 1 [ABSTRACT FROM AUTHOR]

• This is the first report of a direct one-pot synthesis of Pt-Ag double-shelled nanocages (DSNCs). • N , N -Methylenebisacrylamide plays a key role in precisely regulating double-shelled nanocages. • Pt-Ag DSNCs possess numerous surface defects and exposed catalytically active sites. • Pt-Ag DSNCs exhibits excellent performance towards electro-oxidation of methanol (EOM). • DFT calculations demonstrate a bifunctional mechanism of EOM on Pt-Ag DSNCs. Direct methanol fuel cell technology requires high-performance electrocatalysts for practical utilization at the commercial scale. A novel, high-efficiency electrocatalyst composed of hollow porous platinum-silver double-shelled nanocages (Pt-Ag DSNCs) for the electro-oxidation of methanol (EOM) is demonstrated. The Pt-Ag DSNCs were synthesized with a facile one-pot self-template mechanism with the assistance of N, N-Methylenebisacrylamide (MBAA). The double shells can be precisely controlled by regulating the feeding amount of MBAA and the Pt/Ag ratio. The hollow MBAA-based metal polymer acts as a nano-reactor and nucleation site for the deposition of PtAg alloy on its inner (exposed to AgCl nanoparticles) and outer (exposed to bulk solution) sides. To our knowledge, this is the first report of a direct one-pot synthesis of Pt-Ag double-shelled nanocages. Combining a unique double-shelled structure and an optimized bimetallic chemical composition, the Pt-Ag DSNCs (optimized Pt/Ag ratio is 3/1) show more than a two-fold improvement in specific activity and greater stability towards the EOM compared with a commercial Pt catalyst. Density functional theory (DFT) studies demonstrate the introduction of Ag is important for the improvement of EOM performance. The facile synthetic strategy and competitive EOM performance endow Pt-Ag DSNCs with great application potential in direct methanol fuel cells. [ABSTRACT FROM AUTHOR]