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Hansen Solubility Parameters (HSP), viewed in the context of similarity whenever dispersion is focused, offer valuable insights into the surface characteristics of nanoparticles. However, existing methods for determining HSP via the sedimentation of nanoparticles require multiple probe liquids, resulting in time‐consuming, costly experiments with potential health risks. To address this, we developed a two‐step strategy that enables a systematic selection of liquids. The key element of the approach is to first identify the rough location of the Hansen sphere in the three‐dimensional Hansen space using a well‐chosen set of probe liquids of different polarities and chemical structures. Then, depending on the outcome of the first step, a particular choice of liquids is made for the final HSP determination. Taken together, the introduced procedure reduces the amount of required liquids for experiments from currently more than ten to a maximum of seven chosen based on a well‐defined, coherent methodology. Validation was performed on carbon black, non‐pigmentary nano‐scale titania, silicon/carbon composites, and lanthanum cobaltite particles, i. e. relevant materials that are commonly utilized in fuel cells, batteries, cyclohexene oxidation, catalytic combustion, photocatalysis, and heterogeneous Fenton reactions. The study showcases the potential to save time, costs, and efficiently determine HSP values in a comparable manner. [ABSTRACT FROM AUTHOR]

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]

A hybrid of nickel and tungsten carbide on new-diamond (Ni-WC/nD) was synthesized by a microwave-assisted method, in which nickel(tungsten) hydroxide was deposited on carbon black and then reduced carbothermally under N2 atmosphere. Pt nanoparticles (NPs) were deposited on the hybrid to form the Pt/Ni-WC/nD electrocatalyst. XRD and TEM were used to investigate the structure and morphology of Pt/Ni-WC/nD, respectively. The results revealed that Ni and WC particles formed on carbon black during the reduction of nickel(tungsten) hydroxide at 1300 °C under N2, and the amorphous carbon was translated to new-diamond as a result of the catalysis of Ni. The Pt NPs deposited on Ni-WC/nD exhibited a good affinity with the support. We demonstrated that Pt/Ni-WC/nD was an active electrocatalyst for the methanol oxidation reaction (MOR) and the oxygen reduction reaction (ORR). Pt/Ni-WC/nD exhibited a better electrocatalytic activity and durability than Pt/C electrocatalyst for the MOR and ORR. This can be attributed to the strong interaction between the Ni-WC/nD support and Pt and the excellent stability of the new-diamond. [ABSTRACT FROM AUTHOR]

Highly dispersed Pd nanoparticles (NPs) with an average size of 2.7 nm on commercial carbon black (CB, Vulcan XC72) are successfully synthesized by an innovative route without cumbersome heating process and using any surfactant. In view of the significant concerted effects between Pd NPs and electrically conductive CB, the as-prepared Pd/CB catalyst exhibits a ECSA [PdO] value as high as 126.2 m 2 g −1 , which is almost 2.5 times larger than that of commercial Pd/C, allowing it to show an unexceptionable performance for alcohols electro-oxidation in alkaline medium, such as ultrahigh electro-catalytic activity, super electrical conductivity and excellent long-term stability. This approach is also available in the other materials technology required for the practical application of fuel cells. [ABSTRACT FROM AUTHOR]

Electrochemical and structure characteristics of PtCoCr/C-catalyst with platinum content 50 wt % under model conditions and in cathode of membrane-electrode assembly (MEA) of hydrogen-oxygen fuel cell are studied. The metal-phase nanoparticles are shown to represent a PtCo alloy with partial inclusion of chromium, the nanoparticles surface being enriched with platinum. The platinum mass activity and the PtCoCr/C-catalyst high corrosion resistance do not depend on the amount of platinum deposited onto XC72 carbon black (20 or 50 wt %). Herewith the platinum surface area decreases in the same way as the carbon black specific surface area (measured with the BET method); the latter is 227, 169, and 105 m/g for pure carbon black and that containing 20 and 50 wt % Pt, respectively. Testing of the 50PtCoCr/C-catalyst in the MEA cathode active layer in hydrogen-oxygen fuel cell showed performance not inferior to MEAs with pure-platinum systems, the catalyst being more stable. [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]

The development of a high-performance, durable, and less expensive membrane electrode assembly (MEA) composed of a polymer electrolyte membrane and electrocatalysts is important for developing fuel cells. Herein, we described the design and fabrication of an electrocatalyst with carbon black, polybenzimidazole doped with poly(vinylphosphonic acid) (PVPA), and platinum nanoparticles as an electron-conducting support material, an electrolyte, and a metal catalyst, respectively. Most importantly, we used PVPA in place of phosphoric acid, which is a widely used acid dopant, as the acid dopant for both the electrocatalyst and the polymer electrolyte membrane. We reported that the use of PVPA is crucial for the high performance of the MEA because it prevented the leaching of acid molecules from the MEA, which led to high durability compared to that of the phosphoric acid-doped MEAs. [ABSTRACT FROM AUTHOR]

The modification of mesoporous carbon black with polypyrrole (C-PP) facilitates the incorporation of homogeneously dispersed nanosized Ru-Pt particles (1-2 nm) onto the support. Polypyrrole-modified carbon supports were prepared by the addition of different amounts of pyrrole, followed by in situ polymerization through oxidative treatments. The Ru-Pt/C-PP electrocatalysts were tested in the oxygen-reduction reaction in methanol-containing acidic electrolytes by using both conventional electrochemical techniques and in a direct methanol single cell. The performance of Ru-Pt/C-PP was far superior to that of Pt/C for the oxygen-reduction reaction in the direct methanol fuel cell. Under severe methanol-crossover conditions, the maximum power density that was delivered by Ru-Pt/C-PP after degradation tests was decreased by 20 %, whereas that of Pt/C decreased by 75 %. Thus, the presence of Ru oxides in the cathode led to more tolerant electrocatalysts towards the presence of methanol in the reaction medium during the oxygen-reduction reaction. [ABSTRACT FROM AUTHOR]

Abstract: Various Pd–Tb/C electrocatalysts with different Pd/Tb ratios were synthesized and tested for ethanol oxidation in alkaline media. The structure and morphology of the nanocatalysts were investigated using X-ray diffraction and transmission electron microscopy. The data showed that face-centered cubic structures were formed for all the Pd–Tb/C catalysts and a well dispersion of nanoparticles on carbon black was observed. The electrocatalytic properties of the catalysts for ethanol oxidation in alkaline solution were tested by cyclic voltammetry, linear sweep voltammetry and chronoamperometry techniques. It was found that Pd–Tb/C catalysts have higher activity and durability for ethanol oxidation than Pd/C. This may be attributed to the promotion effect of Tb on OH− adsorption. The highest performance was observed for 10%Pd–2%Tb/C in terms of the highest activity, stability and lowest activation energy for ethanol oxidation. [Copyright &y& Elsevier]

Abstract: Antimony doped tin oxide supported on carbon black (ATO/C) has been synthesized using an in situ co-precipitation method, and platinum–ATO/C nanoparticles have been prepared using a consecutive polyol process to enhance the catalyst activity for the methanol oxidation reaction. The Pt–ATO/C electrocatalyst is characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microcopy (SEM), energy dispersive X-ray spectroscopy (EDS) and cyclic voltammetry. The Pt–ATO/C catalyst exhibits a relatively high activity for the methanol oxidation reaction compared to Pt–SnO2/C or commercial Pt/C catalyst. This activity can be attributed to the high electrical conductivities of the Sb-doped SnO2, which induces the electronic effects with Pt catalysts. Pt–ATO/C is a promising methanol oxidation catalyst with high activity for the reaction in direct methanol fuel cells. [Copyright &y& Elsevier]

Carbon blacks such as Vulcan XC-72 are widely used to support platinum (Pt) or Pt alloy catalysts in proton exchange membrane fuel cells. Despite their widespread use, carbon blacks are susceptible to corrosion during fuel cell operations. In this work, the corrosion behaviors of platinized Vulcan XC-72 nanoparticles under thermal and electrochemical conditions were monitored by transmission electron microscopy (TEM). The thermal corrosion experiment was carried out in a gas-cell TEM, which allows for a direct observation of the thermal oxidation behavior of the nanoparticles. The electrochemical corrosion experiment was performed outside of the TEM by loading the nanoparticles on a TEM grid and then electrochemically corroding them step by step followed by taking TEM images from exactly the same nanoparticles after each step. This work revealed four types of structural changes: (i) total removal of structurally weak aggregates, (ii) breakdown of aggregates via neck-breaking, (iii) center-hollowed primary particles caused by an inside-out corrosion starting from the center to outer region, and (iv) gradual decrease in the size of primary particles caused by a uniform removal of material from the surface. These structural changes took place in sequence or simultaneously depending on the competition of carbon corrosion dynamical processes. The results obtained from this work provide insight on carbon corrosion and its effects on fuel cells' long-term performance and durability. [ABSTRACT FROM AUTHOR]

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]

Abstract: An argon glow discharge plasma was used for the reduction of carbon black-supported platinum (Pt) catalysts with high loading of the metal. High dispersion of the Pt on the carbon black was obtained by such plasma reduction, operated at ambient temperature. The average particle size was 1.43nm with 20wt% platinum loading, whereas it was 1.50nm with 40wt% platinum loading. An increase in the loaded amount of Pt did not induce an increase in the particle size. A narrow size distribution has also been achieved. The plasma reduced catalysts show high activities for electro-oxidation of methanol. [Copyright &y& Elsevier]

Without the backing of systematic comparative studies, it is generally accepted by the fuel cell community that Pd nanoparticles are superior to their Pd oxide counterparts towards the electrocatalytic oxidization of small organic molecules. We report an ecofriendly and straightforward approach to synthesizing PdO nanoparticles via an unprecedented microwave assisted thermo-hydrolyzation process. It is found that the catalyst remains in its oxidized state when heating in air and is converted into metallic state under the hydrogen treatment. Surprisingly, the mono-disperse PdO nanoparticles supported on carbon black demonstrates an unexpectedly high activity for FAO, with a mass activity of 2165 A g−1, surpassing that of commercial Pd nanoparticles (844 A g−1). Heat-treatment both in air and hydrogen deteriorates the catalytic activity to less than 50% that of the as-prepared. The better stability of the as-prepared PdO/C relative to commercial Pd is confirmed by repeated cyclic voltammetric as well as chronoamperometric evaluations. In this work, we report an ecofriendly and straightforward approach to synthesizing PdO nanoparticles via an unprecedented microwave assisted thermo-hydrolyzation process. Surprisingly, the PdO nanoparticles supported on carbon black demonstrated an unexpectedly high activity for formic acid oxidation, with a mass activity of 2165 A g−1 measured in 0.5 M H 2 SO 4 +0.5 M HCOOH at room temperature, surpassing that of commercial Pd nanoparticles (844 A g−1). Image 1 • Unprecedented microwave assisted thermo-hydrolyzation to synthesize mono-dispersed PdO (∼3 nm). • XPS/XAS confirmed the nature of the as-prepared PdO and conversion into metallic Pd in H 2 treatment. • PdO/C exhibits an activity of 2165 A g−1 (vs. 844 A g−1 for Pd black) and high stability for FAO. [ABSTRACT FROM AUTHOR]