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Supported ordered intermetallic nanoparticles are of significant interest for catalysis applications owing to their unique surface/near-surface structures and electronic properties. However, the synthesis of small-sized intermetallic catalysts with high mass activity remains a formidable challenge, as high temperatures annealing treatments are generally requisite to achieve ordered intermetallic structures but lead to undesired larger crystallites. Here, we report an industrially relevant impregnation approach for the scalable synthesis of small-sized platinum-based intermetallic nanoparticle catalysts by regulating inter-particle distance on carbon black supports to mitigate metal sintering in high-temperature annealing. We construct a library consisting of 18 binary Pt-based intermetallic nanoparticle catalysts with an average size of < 5 nm. The prepared intermetallic catalyst libraries exhibit outstanding proton-exchange-membrane fuel cells performance, including high mass activities of 1.3–1.8 A mg Pt –1, large peak power densities of 1.2–1.4 W cm–2 in H 2 -air cells, and efficient Pt utilization of ∼0.07 g kW–1 at rated power. [Display omitted] • Intermetallic compounds (IMC) have unique strain/electronic effects in catalysis. • A family of small size Pt-based IMCs was achieved by regulating inter-particle distance. • Small size and ordered IMC structure guarantee outstanding performance in fuel cell. [ABSTRACT FROM AUTHOR]

Ni/C electrocatalysts were prepared by chemical deposition of nickel nanoparticles on Vulcan XC-72R carbon black using microwave irradiation technique. The time of microwave irradiation during the reduction step and nickel weight percentage were varied. This was found to affect the morphology of formed Ni/C powder as shown by TEM analysis. Increasing nickel weight percentage results in the formation of more aggregated deposits. The electrocatalytic activity of different Ni/C samples towards methanol oxidation reaction in KOH solution was studied by applying cyclic voltammetry, chronoamperometry and electrochemical impedance spectroscopic techniques. Ni/C electrocatalyst containing 30 wt.% Ni [Ni/C-30] shows 5.2 times higher electrocatalytic activity than that with 10 wt.% Ni [Ni/C-10]. Heating Ni/C powder into microwave oven using the pulse mode of 30 s on/10 s off forms the most stable electrocatalyst for prolonged oxidation reaction. Electrochemical impedance measurements show that Ni/C-30 electrocatalyst has the lowest impedance value of 0.022 kΩ cm 2 , while the highest one is for Ni/C-10 [0.331 kΩ cm 2 ] in (0.4 M methanol + 0.5 M KOH) solution at 500 mV. It confirms that Ni/C-30 has the highest electrocatalytic activity towards methanol oxidation reaction. [ABSTRACT FROM AUTHOR]

Highlights: [•] Plasma treatment of carbon black and metallic precursor in a solid form is efficient to form small nanoparticles. [•] The decomposition of the metallic precursor depends on the gas nature and on the plasma power. [•] Interaction between plasma species and the carbon black support induces chemical and structural defects. [•] Chemical and structural defects act as anchoring sites for nanoparticle nucleation. [Copyright &y& Elsevier]

Abstract: The influence of the structure and morphology of PtRu nanoparticles supported on functionalized carbon black has been investigated for CO and methanol electrooxidation in a half-cell and in a DMFC single cell. Carbon black was treated with HNO3 to obtain an oxidized surface (Vulcan-N), and PtRu nanoparticles supported on Vulcan-N were prepared via impregnation, Bönnemann''s method and the sulfito-complex route. Temperature programmed reduction (TPR) measurements evidence the presence of RuO2·xH2O phase in the catalyst obtained by the sulfito-complex route. This phase was stabilized by metal–support interaction, whereas alloy characteristics were estimated for PtRu catalyst obtained by impregnation and Bönnemann''s method. The nature of the precursor–support interaction, induced by the nature of the functional groups on the carbon surface, affects the structure of the electrocatalyst and subsequent behavior in electroactivity. When synthesized through Bönnemann''s method, the surface oxygen-containing groups of the support seem to be unable to stabilize the anhydrous precursors of platinum and ruthenium, yielding crystalline RuO2. Methanol electrooxidation performance was clearly different in the three catalysts, whereas only a few negligible differences were observed in CO oxidation. The superior performance in DMFC of the catalysts obtained by the sulfito-complex route accounts for both the presence of RuO2·xH2O species and the functionalization of carbon black. [Copyright &y& Elsevier]

• The Pd/NCB@NGS with unique 3D hierarchical architecture was fabricated by facile strategy. • The size of Pd NPs on NCB@NGS can be controlled without surfactant. • The Pd/NCB@NGS reveals impressive electrochemical EOR performance. • The exciting EOR behavior is owing to the prominent roles of unique 3D hierarchical architecture with abundant N atoms. The engineering efficient electrocatalysts with low cost, high activity and robust durability for ethanol oxidation reaction (EOR) is vital for large-scale commercializing direct ethanol fuel cells. Herein, the "surface-clean" Pd nanoparticles anchored on the nitrogen-doped carbon black embedding nitrogen-doped graphene (Pd/NCB@NGS) with unique three-dimensional hierarchical architecture was fabricated through a self-assembly strategy followed by a surfactant-free chemical reduction. The size of Pd nanoparticles on NCB@NGS can be controlled without surfactant. As an electrocatalyst for EOR, the Pd/NCB@NGS displays improved electrocatalytic performance compared with commercial Pd/C and other counterparts, due to the prominent roles of unique three-dimensional hierarchical architecture with abundant nitrogen atoms. Particularly, the electrocatalytic EOR property of Pd/NCB@NGS-2 (the mass ratio of OCB/GO is 1:1) is optimal among the tested-electrocatalysts, owing to it balances the clash between increased nitrogen atoms and decreased electrical conductivity. This study also developed a superior carbon-based material for various electrocatalysts and beyond. [ABSTRACT FROM AUTHOR]