An important feature of this research is the investigation of the de-alloyed catalysts based on the nanoparticles with a simple structure (alloy) and a complex structure (gradient). The resulting ...samples exhibit the 2–4 times higher mass activity in the ORR compared with the commercial Pt/C. The novelty of this study is due to the application of the express-electrochemical experiment to register the trend of changes in the ORR activity caused by rearranging the structure of bimetallic nanoparticles. The state-of-the-art protocol makes it possible to establish the dependence of properties of the de-alloyed catalysts on the nanoparticles’ structure obtained at the stage of the material’s synthesis. The study shows the possibility of determining the rate of the ongoing reorganization of bimetallic nanoparticles with different architectures. The PtCu/C electrocatalysts for proton-exchange membrane fuel cells presented in this work are commercially promising in terms of both the high functional characteristics and the production by facile one-pot methods.
The influence of the atmosphere composition (CO, Ar, air), in which wet synthesis of Pt/C electrocatalyst was carried out, on the structural and morphological characteristics, and electrochemical ...behavior of electrocatalysts have been studied. For comparison, commercial Pt/C electrocatalysts with the same platinum loading were also studied. It has been shown that the adsorption of CO molecules on the surface of the growing platinum nuclei leads to the decrease in the average size of the nanoparticles and the narrowing of the size distribution in the Pt/C. Homemade electrocatalysts, with the values of electrochemically active surface area being from 94 to 139 m
2
g
−1
(Pt), prove to be in no way inferior to their commercial counterparts in oxygen reduction reaction mass activity. Durability of the homemade Pt/C samples in accelerated stress tests exceeds durability of the commercial ones.
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This article provides relevant information on the catalysts’ morphological characteristics that allow for the optimal combination of activity and durability of the materials for proton-exchange ...membrane fuel cells. The home-made Pt/C and PtCu/C catalysts have been established to have at least by 20% higher values of the mass activity in the oxygen reduction reaction than the commercial Pt/C analogue (HiSPEC 3000, Johnson Matthey). The detailed analysis of the microstructure by transmission electron microscopy and the electrochemical parameters by electrochemical surface-sensitive methods after the stress testing has allowed estimating the contribution of various mechanisms to the degradation process. After the stress testing, the residual activity in the oxygen reduction reaction of the home-made materials has proved to be at least more than double that of the commercial Pt/C catalyst. A specific feature of this work is the presented correlation between the morphology and the electrochemical behavior of the catalysts, with this interconnection appearing to be a valuable resource for a wide range of scientists.
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•The rapid and facile synthesis methods of the highly active catalysts are presented.•The PtCu/C catalyst is 2.5 times more active in the ORR than the commercial Pt/C.•The testing is conducted within the protocols with the long-term cycling and the potential hold.•The home-made materials are more robust against degradation than the commercial one.•The integrated approach to studying the catalysts' durability is presented.
This paper proposes an environmentally friendly one-pot synthesis approach for the PtCu and PtNi nanoparticles with the gradient structure on the carbon support. This method offers exceptional ...advantages over other approaches. Among them there is a surfactant-free synthesis, being low-temperature, simple, fast, and one-pot. The bimetallic electrocatalysts with a reduced platinum content for proton-exchange membrane fuel cells have been obtained. The proposed method is promising in terms of scaling and transition to commercial production. In this study, we first attempted to apply the gradient synthesis strategy to the PtNi/C catalysts in order to make this method versatile. We obtained the high-performance PtNi/C and PtCu/C catalysts, exhibiting the specific ORR activity higher than that of the commercial Pt/C catalyst by 3 and 4.6 times, respectively.
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•New Pt-based nanostructured ORR electrocatalysts were obtained by a simple, versatile, and scalable method.•The PtCu and PtNi nanoparticles with Pt overlayers supported on carbon were synthesized by a gradient strategy.•PtNi/C and PtCu/C showed enhanced activity in the ORR compared with the commercial Pt/C.•The surfactant-free one-pot synthesis was used to obtain the PtNi and PtCu nanoparticles.•The environmentally friendly method was used to prepare Pt-based electrocatalysts.
The identification of tissue-specific promoters for gene therapeutic constructs is one of the aims of complex tumor therapy. The genes encoding the fibroblast activation protein (
) and the ...connective tissue growth factor (
) can function in tumor-associated stromal cells but are practically inactive in normal adult cells. Accordingly, the promoters of these genes can be used to develop vectors targeted to the tumor microenvironment. However, the efficiency of these promoters within genetic constructs remains underexplored, particularly, at the organism level. Here, we used the model of
embryos to study the efficiency of transient expression of marker genes under the control of promoters of the
,
, and immediate early genes of
(CMV). Within 96 h after the injection of vectors, the
and CMV promoters provided similar equal efficiency of reporter protein accumulation. In the case of the
promoter, a high level of reporter protein accumulation was observed only in certain zebrafish individuals that were considered developmentally abnormal. Disturbed embryogenesis was the factor of changes in the exogenous
promoter function. The data obtained make a significant contribution to understanding the function of the human
and
promoters within vectors to assess their potential in gene therapy.
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•Excellent ORR activity was achieved on PtCu/C electrocatalyst with N-doped carbon support.•High uniformity of NPs’ spatial distribution results in high durability of PtCu ...catalyst.•IL-TEM provides correlation between thermal and electrochemical stability of bimetallic NPs.
A high-performance electrocatalyst based on bimetallic platinum-containing nanoparticles for PEMFCs has been presented. The combination of bimetallic nanoparticles and an N-doped carbon support ensures high ORR activity and stability of the catalyst. The single-reactor method to obtain the material and its higher functional characteristics allow considering the resulting PtCu/C-N electrocatalyst as a promising commercial product. An extended study of morphological characteristics has been conducted to understand the processes of evolution for this material. The in-situ IL-TEM research has allowed studying in detail the degradation process for the material during high-temperature treatment by analyzing changes in the type of histograms of the nanoparticles size distribution and testing the method for calculating the number of their intersections to assess the dynamics of the material degradation.
Within this research, we studied the structural–morphological and electrochemical characteristics of the PtNi/C catalysts synthesized via the two-stage sequential reduction of precursors. We also ...carried out a comparative study of the obtained bimetallic catalysts and their commercial Pt/C analog. The use of triethylamine as a surfactant as well as the acid treatment as an additional synthesis stage, were shown to have a positive effect on the functional parameters of the bimetallic electrocatalysts. The resulting PtNi/C electrocatalyst demonstrates a mass activity value of 389 A gPt−1, which is 1.6 times higher than this parameter for a commercial analog.
The purpose of this work is study to correlation between structure, electrochemically active surface area and activity in the oxygen reduction reaction and methanol electrooxydation of obtained by ...wet-synthesis PtM/C (M = Ni, Co, Cu) materials with atomic ratio Pt-M 1:1 and a commercial Pt/C material E-TEK 20. Bimetallic PtM/C electrocatalysts were obtained by chemical reduction of metals from their compounds a carbon (Vulcan XC-72, Cabot) suspension based on two-component water-organic solvent at pH = 10 (excess of NH3). The characterization of PtM/C materials was performed by powder X-ray diffraction (XRD), transmission electron microscopy (TEM) and cycle voltammetry (CV). The average crystallite size according XRD for the received materials have from 1.7 to 2.5 nm and a platinum content of materials is 20–27 % by weight. It was found that PtM/C catalysts have a smaller value of surface area – 40 m2/g (Pt) as compared with Pt/C catalyst – 100 m2/g(Pt). But despite this fact mass-activity (activity per mass of platinum, A/g(Pt)) in the oxygen reduction reaction (ORR) PtCu/C catalyst have not inferior to commercial Pt/C material. All of PtM/C materials demonstrated a high speci c activity (activity per real surface area, mA/cm2) in the reaction of methanol oxidation (MOR) and a high tolerance for intermediate of methanol oxidation. It was found that the alloying of various d-metals can have a positive effect on the activity in the reaction of oxygen electroreduction, methanol electrooxydation and a high tolerance for intermediate of methanol oxidation. However, for increase of the mass-activity it necessary to obtain of PtM/C catalysts with higher surface area.
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