Carbon-Supported Pt-Based Alloy Electrocatalysts for the Oxygen Reduction Reaction in Polymer Electrolyte Membrane Fuel Cells: Particle Size, Shape, and Composition Manipulation and Their Impact to Activity

In the paper

“However, high-temperature heat treatment can cause agglomeration of particles, reduction of specific surface area, and broadening of particle size distribution.”

What the sources say

• Partly supported

  In “Glucose electro-oxidation studies” (page unavailable), the paper says heat treatment can increase particle size and thereby reduce catalyst active area, supporting the surface-area concern in substance. It does not establish that high-temperature treatment causes agglomeration or broadens the particle-size distribution; it reports treatment at 450 °C without agglomeration and cites improved particle distribution at 400–550 °C. (LLM, conf=0.86)

  cites [234] Singh B., 2012, ECS J. Solid State Sci. Technol. sourceExperimental — accuracy not yet measured
• Disputed

  In the XPS results section (page not provided), the paper reports that increasing heat-treatment temperature from 300°C to 600°C caused no substantial change in Pt nanoparticle size or dispersion. It describes the resulting particles as well dispersed, contrary to attributing heat-induced agglomeration and a broadened size distribution to this study. The passage does not report a reduction in specific surface area from heat treatment. (LLM, conf=0.83)

  Checked by a reasoning model — may be wrong.

  cites [235] Sheng W., 2011, J. Electrochem. Soc. sourceExperimental — accuracy not yet measured
• ?Not checked — no full text of the sourcecites [236] Chandan A., 2013, J. Power Sources source

In the paper

“Dealloying resulted in an increase in mass activity from 0.21 to 0.29 A mg -1 Pt at 0.90 V, and an increase in specific activity from 300 to 580 A cm -2 Pt .”

What the sources say

• Disputed

  The Results and Discussion (RDE measurements; page unavailable) say that dealloying increased mass activity but that specific activity at 0.90 V slightly trailed the annealed sample—not that it rose from 300 to 580. The catalyst-development discussion (page unavailable) reports a dealloyed mass activity of 0.34 A/mg Pt, rather than the claimed 0.29 A/mg Pt. (LLM, conf=0.90)

  Checked by a reasoning model — may be wrong.

  cites [281] Dutta I., 2010, J. Phys. Chem. C sourceExperimental — accuracy not yet measured

In the paper

“The detailed degradation mechanisms 116,117 revealed the transportation of Pt ions through liquid and/or ionomer and the transportation of electrons through carbon support, respectively.”

What the sources say

• ?Not checked — no full text of the sourcecites [116] Paulus U. A., 2002, Electrochim. Acta source
• Partly supported

  The Carbon black Supports passage (section labeled References; page unavailable) says the carbon support must provide high electrical conductivity, which supports the electron-transport part in general. The Stability passage describes base-metal ions leaching into the membrane, not Pt ions moving through liquid or ionomer. Neither passage establishes the claimed detailed degradation mechanism. (LLM, conf=0.78)

  cites [117] Ralph T. R., 2002, Platinum Met. Rev. sourceExperimental — accuracy not yet measured

In the paper

“They found that alloying with Ru can cause electronic effects on the Pt such as an increase in the number of Pt d band vacancies and a decrease in the Pt-Pt distance.”

What the sources say

• Supported

  The Results and Discussion section states that alloying with Ru increases Pt d-band vacancies. The Pt EXAFS section states that alloying with Ru decreases the Pt–Pt bond distance; it also reports increased vacancies alongside bond-length contraction at 0.0 V. Page numbers are unavailable in our copy. (LLM, conf=0.94)

  cites [81] McBreen J., 1995, J. Electrochem. Soc. source

In the paper

“In Pt alloys, Pt tends to congregate in the first layer and then be induced to form a surface strain, which strongly influences its reactivity, depending on the type of transition metal(s) in the alloy.133”

What the sources say

• Supported

  Section 2.3 (p. 9) states that Pt tends to congregate in the first layer of Pt alloys, introducing surface strain that strongly affects reactivity. It also says the magnitude of the effect depends on the transition metal. (LLM, conf=0.95)

  cites [133] Bing Y., 2010, Chem. Soc. Rev. source

In the paper

“High reaction temperature and a high degree of solute supersaturation (i.e., the ratio of saturation solute concentrations to equilibrium solute concentration) can accelerate nucleation.”

What the sources say

• ?Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  cites [194] Volmer M., 1926, Phys. C
• ?Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  cites [195] Volmer, M. Kinetic der Phasbildung, Dresden, Steinfopff, Leipzig , 1939.
• Partly supported

  In the crystal-growth discussion (page unavailable), the paper says that, unless supersaturation is too high, a considerable time elapses before a new nucleus forms. That supports the supersaturation part for vapor, but the copy does not establish that high reaction temperature accelerates nucleation or address supersaturation defined by solute concentrations. (LLM, conf=0.84)

  cites [196] Becker R., 1935, Ann. Phys. sourceExperimental — accuracy not yet measured

In the paper

“Sui et al. 334 successfully synthesized PtFe nanotubes using AAO membrane as a hard template.”

What the sources say

• Supported

  In “Nanotube magnetism” (page not available in our copy), Sui et al. report producing FePt nanotubes by hydrogen reduction in the pores of porous alumina templates. This supports the citing sentence’s description of template-based synthesis; the paper writes the alloy as FePt rather than PtFe and calls the template porous alumina rather than AAO. (LLM, conf=0.90)

  cites [334] Sui Y. C., 2004, Appl. Phys. Lett. source

In the paper

“Shao's group believed that PEO segments in the PEO-PPO-PEO triblock copolymer were able to reduce metal ions, thus forming cavities (pseudocrown ethers) binding PdCl 42-from the starting precursors: the bound PdCl 4 2-ions might then be reduced via oxidation of the oxyethylene segments by the metal center.311,312”

What the sources say

• Partly supported

  Split into 2 atoms — 0 confirmed, 2 partially supported, 0 disputed, 0 misattributed, 0 unverifiable. Expand the claim to see per-atom verdicts.

  cites [311] Alexandridis P., 2011, Eur. Polym. J. sourceExperimental — accuracy not yet measured
• ?Not checked — no full text of the sourcecites [312] Piao Y., 2007, Small source

In the paper

“Carbon-supported Pt-alloy systems are known as solid solutions of Pt and other metal(s), among which carbonsupported Pt-based bimetallic alloys are popular electrocatalysts in PEMFCs.13,57,396,397”

What the sources say

• ?Not checked — no full text of the sourcecites [13] Gasteiger H. A., 2005, Appl. Catal. B: Environ. source
• ?Not checked — no full text of the sourcecites [57] Yu X., 2007, J. Power Sources source
• ?Not checked — no full text of the sourcecites [396] Brouzgou A., 2012, Appl. Catal. B Environ. source
• Partly supported

  Section 4 says Pt and Ru can form a solid solution in a binary alloy, depending on their ratio; it does not say that Pt alloys generally are solid solutions. Sections 1 and 3 discuss Pt-based bimetallic electrocatalysts for fuel-cell reactions, but do not establish that carbon-supported Pt-based bimetallic alloys are popular in PEMFCs. Section 7 discusses a carbon-supported Pt–ceria material for PEMFCs, not a bimetallic alloy. (LLM, conf=0.86)

  cites [397] Kulesza P. J., 2013, Electrochim. Acta sourceExperimental — accuracy not yet measured

In the paper

“The composition of Pt increased from 20 to 29 wt % while the Cu content decreased from 20 to 5.4 wt %.”

What the sources say

• Partly supported

  In Results and Discussion, under “Synthesis and Chemical Characterization” (page not available), the paper says dealloying removed a significant fraction of Cu and raised the Pt/Cu molar ratio from 0.3 to 1.8. That supports the reported change in composition, but the available passage does not give the claimed weight percentages; it points to Table 1 for metal contents. (LLM, conf=0.82)

  cites [281] Dutta I., 2010, J. Phys. Chem. C sourceExperimental — accuracy not yet measured

In the paper

“At the cathode loading of 0.077-0.37mg Pt cm -2 in the MEA, the tested current density was found to be dependent on some factors such as temperature, pressure, and relative humidity (RH).”

In the paper

“Among these approaches, wet chemical synthesis has been employed the most.”

In the paper

“Alloying has become an attractive strategy to develop advanced Pt-based electrocatalysts, [23][24][25][26][27][28][29] in which the addition of another metal can form a Pt alloy 30 and thus alter the availability of active surface sites (the ensemble effect) or the binding strength of reactants, intermediates, products, and spectator species (the electronic and/or strain effect).31”

What the sources say

• ?Not checked — no full text of the sourcecites [30] Maroun F., 2001, Science source
• ?Not checked — no full text of the sourcecites [31] Burch R., 1982, Acc. Chem. Res. source

In the paper

“Polymer electrolyte membrane fuel cells (PEMFCs) are among the most promising candidates for the reliable and efficient conversion of hydrogen, produced from fossil or renewable sources, into electric power in automotive, distributed power generation, and portable electronic applications on a large scale.[2][3][4][5][6][7][8][9][10][11]”

What the sources say

• ?Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  cites [2][3][4][5][6][7][8][9][10][11]

In the paper

“They concluded that the specific surface area of the support as well as the oxygen surface groups affected the particle size and dispersion and catalytic performance.”

What the sources say

• ?Not checked — no full text of the sourcecites [107] Limpattayanate S., 2014, Renew. Energy source

In the paper

“It is well-known that carbon support is not a mere inert material 69 and it can alter the system's Galvani potential, raise the electronic density in the catalysts, and lower the Fermi level, which favor the electron transfer at the electrodeelectrolyte interface and thus accelerate the electrode processes.57,70”

What the sources say

• ?Not checked — no full text of the sourcecites [69] Calderón J. C., 2012, Int. J. Hydrogen Energy source
• ?Not checked — no full text of the sourcecites [57] Yu X., 2007, J. Power Sources source
• ?Not checked — no full text of the sourcecites [70] Zenyuk I. V., 2012, J. Phys. Chem. C source

In the paper

“It was concluded that Vulcan carbon provided significantly higher active surface area probably due to a good interaction of Pt-Pd with Vulcan than with HSAG even though the later had a higher surface area than the former.”

What the sources say

• ?Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  cites [109] Gamez, A.; Richard, D.; Gallezot, P.InResume des Journees d’Etude Piles a Combustible;Paris, France, 1999; p401.

In the paper

“This was further supported by X-ray photoelectron spectroscopy (XPS) studies that showed Pt as an electron donor to carbon and their interaction was dependent on the Fermi-level of electrons in both Pt and carbon.74”

What the sources say

• ?Not checked — no full text of the sourcecites [74] Coloma F., 1996, Appl. Catal., A source

In the paper

“The surface physicochemical properties and the structure of carbon materials play an important role on the activity and the stability of the resultant carbon supported Ptalloy catalysts because the interaction between carbon and Ptalloy can modify the physicochemical and electronic structure of Pt-alloy which in turn influences the catalytic activity and durability.[61][62][63][64][65]”

What the sources say

• ?Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  cites [61][62][63][64][65]

In the paper

“They found a further shift to higher energy values for the Pt 4f 7/2 of PtRu/C by 0.2-0.3eV with respect to pure Pt/C because of an enhanced Ptcarbon interaction or smaller Pt particle size.”

What the sources say

• ?Not checked — no full text of the sourcecites [79] Antolini E., 2001, J. Solid State Electrochem. source

In the paper

“In the research on carbon-supported Pt-alloy catalysts, more and more attention has been paid to the interaction between Pt-alloy and carbon support which affects the growth, the structure, and the dispersion of Pt-alloy nanoparticles on the carbon support 57,[66][67][68] and is closely related to the size, shape, and composition of Pt-alloy nanoparticles.”

What the sources say

• ?Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  cites 57,[66][67][68]

In the paper

“According to Bogotski and Snudkin, 84 however, the rise in electron density on Pt-alloy could be attributed to carbon support synergism on the basis of changes in the electronic state of Pt after its deposition, thus enhancing the electrocatalytic activity.”

What the sources say

• ?Not checked — no full text of the sourcecites [84] Bogotski V. S., 1984, Electrochim. Acta source

In the paper

“With all three carbon-supported Pt-Pd catalysts being prepared by a seeding and impregnation method, the Pt-Pd/Vulcan XC-72 showed a better catalyst dispersion, smaller particle size (∼6.78nm), a higher Pt:Pd ratio ( 49.6:50.4),and the highest ORR activity under the PEM fuel cell testing condition.”

What the sources say

• ?Not checked — no full text of the sourcecites [107] Limpattayanate S., 2014, Renew. Energy source

In the paper

“After the observation by using a combination of XPS, extended X-ray absorption fine structure (EXAFS), and ESR measurements on a carbon-supported PtRu system, Goodenough and Manoharan 80 concluded that the synergistic catalytic effect could be attributed to an intra-alloy electron transfer from Ru to Pt.”

What the sources say

• ?Not checked — no full text of the sourcecites [80] Goodenough J. B., 1989, Chem. Mater. source

In the paper

“It can be concluded from the discussion above that the electrons in a carbon supported Pt-alloy system have been proved to transfer not only within Pt-alloy, but also from Ptalloy to carbon.[71][72][73][74][75][76][77][78]”

What the sources say

• ?Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  cites [71][72][73][74][75][76][77][78]

In the paper

“The carbon support may not only modify the electronic character of the Pt-alloy 52 but also influence the shape and distribution of the deposited Pt-alloy particles.102,103”

What the sources say

• ?Not checked — no full text of the sourcecites [52] Antolini E., 2009, Appl. Catal., B source
• ?Not checked — no full text of the sourcecites [102] Trogadas P., 2014, Carbon source
• ?Not checked — no full text of the sourcecites [103] Augustine R. L., 1996 source

In the paper

“The strong wetting interaction for the alloy can modify the morphology of the particles at the metalcarbon interface, likely altering the alloy electronic structure and contributing to the 1.8 fold enhanced ORR activity over pure Pt.”

What the sources say

• ?Not checked — no full text of the sourcecites [83] Slanac D. A., 2012, Electrochim. Acta source

In the paper

“Inspite of the positive impact of carbon on the catalytic activity, the reported oxidation of carbon support may cause a severe sintering/agglomeration of Pt-alloy nanoparticles under longterm fuel cell operation 110,111 and thus the decrease of electrocatalytic surface area, resulting in the degradation of catalyst and the decrease of catalytic activity and fuel cell performance.3,[112][113][114]”

What the sources say

• ?Not checked — no full text of the sourcecites [110] Kou R., 2011, J. Am. Chem. Soc. source
• ?Not checked — no full text of the sourcecites [111] Siburian R., 2014, Int. Res. J. Pure Appl. Chem. source
• ?Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  cites 3,[112][113][114]

In the paper

“Well-defined shapes of Pt-based nanocatalysts can mimic the catalytic property of the bulk metal but exhibit superior catalytic activity due to the manipulation of crystal facet 147,148 that allow the fine-tuning of both the selectivity and the reactivity for many major catalytic reactions, so as to achieve high catalytic performance.[149][150][151][152]”

What the sources say

• ?Not checked — no full text of the sourcecites [147] Stamenkovic V. R., 2007, Science source
• ?Not checked — no full text of the sourcecites [148] Chen J., 2009, Nano Today source
• ?Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  cites [149][150][151][152]

In the paper

“To date, many carbon-supported Pt-alloy catalysts (PtM/C, M = Co, 159,160 Ni, 161 Cu, 159 Fe, [162][163][164] Cr, 165 Au, 166 Pd, 167,168 W, 169 etc.) have been successfully synthesized.”

What the sources say

• ?Not checked — no full text of the sourcecites [159] Xiong L., 2005, J. Electrochem. Soc. source
• ?Not checked — no full text of the sourcecites [160] Kim J. W., 2011, Int. J. Hydrogen, Energy source
• ?Not checked — no full text of the sourcecites [161] Mukerjee S., 1995, J. Phys. Chem. source

In the paper

“Pt supported carbon particles are prone to degradation during fuel starvation due to the reaction (C + 2H 2 O → CO 2 +4 H + +4 e -) while the oxidation of carbon is catalyzed by the presence of Pt. 118”

What the sources say

• ?Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  cites [118] Passalacqua, E.; Vivaldi, M.; Giordano, N.; Anotonucci, P. L.; Kinoshita, K. Proceedings of the 27th Intersociety Energy Conversion Engineering Conf. ; 1992; Vol.929294, pp3.425–3.431.

In the paper

“In addition, it is suggested that a nanostructure with high-index facets exhibits higher catalytic activity than common nanostructures with low-index facets because more atoms are added at the former's steps, edges, and kinks.148,[156][157][158]”

What the sources say

• ?Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  cites 148,[156][157][158]

In the paper

“Also, catalyst sintering or agglomeration is another problem for the reduction of fuel cell durability because the catalyst sintering could reduce the electroactive surface area of the Pt catalyst, lower the Pt utilization, and degrade its catalytic activity.115”

What the sources say

• ?Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  cites [115] Garland, N.Fuel Cells Plenary; 2008 DOE Hydrogen Program Merit Review and Peer Evaluation Meeting, 2008.

In the paper

“The carbon support can be converted to CO 2 and Pt may be lost from the electrode, leading to loss of fuel cell performance.”

In the paper

“They found that, with increasing particle size, the catalytic rate per surface site of Au particles sharply increased, whereas a decrease was observed for Pt particles as the particle size decreased.”

What the sources say

• ?Not checked — no full text of the sourcecites [131] Nørskov J. K., 2008, Chem. Soc. Rev. source
• ?Not checked — no full text of the sourcecites [132] Meier J., 2004, Chem. Phys. Lett. source

In the paper

“They found that the catalytic properties were determined by the thickness of the Pt skeleton layer, which depended on the initial composition of the Pt-bimetallic alloy catalysts.173”

What the sources say

• ?Not checked — no full text of the sourcecites [173] Wang C., 2011, Adv. Funct. Mater. source

In the paper

“However, the relationship between electrocatalytic activity and alloy composition in Pt-alloy catalysts does not follow a simple monotonic trend, since the concentration of different alloying elements can substantially affect the catalytic performance due to the resulting changes in intrinsic properties (e.g., electronic structure and surface segregation).147,170”

What the sources say

• ?Not checked — no full text of the sourcecites [147] Stamenkovic V. R., 2007, Science source
• ?Not checked — no full text of the sourcecites [170] Wang C., 2012, ACS Catal. source

In the paper

“It has been reported that carbon-supported Pt alloy can achieve at least two to four times greater ORR activity compared to Pt/C catalysts, due to a positive shift in the onset potential for OH ads formation on the alloy catalyst.13,[123][124][125][126]”

What the sources say

• ?Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  cites 13,[123][124][125][126]

In the paper

“With the addition of a metal (M), the Pt content in the catalyst decreases, as does the cost of materials.”

In the paper

“The moderately compressed {111} facets were most conducive to ORR on small nanoparticles, which could result in the compressive strain effect and thus enhance the ORR activity.”

What the sources say

• ?Not checked — no full text of the sourcecites [155] Wang J.-X., 2009, J. Am. Chem. Soc. source

In the paper

“As a result, the precious metal is prone to nucleate first and grow into separate nanoparticles or form Pt-rich regions in the product.”

What the sources say

• ?Not checked — no full text of the sourcecites [179] Chen M., 2004, J. Am. Chem. Soc. source
• ?Not checked — no full text of the sourcecites [180] Ahrenstorf K., 2008, Adv. Funct. Mater. source

In the paper

“Steric stabilization is the other mechanism (Figure 5B), 205 which can be achieved by the coordination of sterically demanding nonionic surfactants or polymers that produce strong repulsion between particles and droplets as protective shields on a metallic surface.”

What the sources say

• ?Not checked — no full text of the sourcecites [205] L. D. Pachón L. D., 2008, Appl. Organometal. Chem. source

In the paper

“However, the size of the CTABmediated Pt 3 Co x /C catalyst increased only slightly from 2.2 to 2.8 nm, because it had a lower annealing temperature of 250 °C, at which agglomeration was not induced.”

What the sources say

• ?Not checked — no full text of the sourcecites [218] Kim J.-W., 2011, Int. J. Hydrogen Energy source

In the paper

“Electrostatic stabilization is one of the mechanisms: the attraction of van der Waals forces is counterbalanced by the repulsion of the Coulomb forces acting between the negatively charged colloidal particles”

What the sources say

• ?Not checked — no full text of the sourcecites [206] Ozkar S., 2002, J. Am. Chem. Soc. source

In the paper

“They found that the particle sizes of 40 wt % Pt 3 Co x /C were smaller than those of commercial 40 wt %Pt/C; when the amount of stabilizer was 15 times the total moles of Pt and Co, the order of sizes was commercial ( 3.3 nm) > SA-15 (2.7 nm) > TOAB-15 (2.5 nm) > OAM-15 (2.2 nm)”

What the sources say

• ?Not checked — no full text of the sourcecites [218] Kim J.-W., 2011, Int. J. Hydrogen Energy source

In the paper

“The two main mechanisms for stabilization against aggregation 205,206 are shown in Figure 5.”

What the sources say

• ?Not checked — no full text of the sourcecites [205] L. D. Pachón L. D., 2008, Appl. Organometal. Chem. source
• ?Not checked — no full text of the sourcecites [206] Ozkar S., 2002, J. Am. Chem. Soc. source

In the paper

“The average size of the obtained Pt-Ni particles was approximately 3.4 nm, regardless of heat treatment, since 300 °C was not sufficient to sinter carbon-supported Pt-Ni alloy nanoparticles and thus resulted in incomplete alloying (∼35%).”

What the sources say

• ?Not checked — no full text of the sourcecites [207] Jeon T.–Y., 2009, J. Phys. Chem. C source

In the paper

“According to Lamer's plot, 181 both a fast nucleation step and gradual growth on formed nuclei can result in a monodispersed and homogeneous alloy nanomaterial, which is particularly advantageous for the synthesis of Pt-alloy nanoparticles with high catalytic activity.”

What the sources say

• ?Not checked — no full text of the sourcecites [181] Lamer V. K., 1950, J. Am. Chem. Soc. source

In the paper

“In general, protective agents are used to stabilize nanostructured colloidal metal and prevent agglomeration.”

What the sources say

• ?Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  cites [202] Bönnemann H., 2004, J. New Mater. Electrochem. Systems
• ?Not checked — no full text of the sourcecites [203] Bönnemann H., 2004, Chem. Ind. source
• ?Not checked — no full text of the sourcecites [204] Zhou J., 2009, J. Colloid Interface Sci. source

In the paper

“In particular, the three carboxyl anions of CA can be adsorbed onto the surface of metal particles and exert either hydrophobic or Coulombic effects on the particles, thereby stabilizing nanoparticles.”

What the sources say

• ?Not checked — no full text of the sourcecites [211] Ozkar S., 2002, J. Am. Chem. Soc. source

In the paper

“It was thus concluded that CTAB is the most appropriate stabilizer for the fabrication of the Pt 3 Co x /C catalyst because the dispersion of Pt-Co particles on the carbon support is much more uniform than in a commercial Pt/C catalyst.”

What the sources say

• ?Not checked — no full text of the sourcecites [218] Kim J.-W., 2011, Int. J. Hydrogen Energy source

In the paper

“According to classical nucleation theory, three key variables control the rate of nucleation: temperature, surface free energy, and degree of supersaturation.”

What the sources say

• ?Not checked — no full text of the sourcecites [12] Peng Z., 2009, Nano Today source

In the paper

“However, some polymers, including PVP, bind too strongly bound to the nanoparticle surface to be removed, which can result in decreased catalytic performance.”

What the sources say

• ?Not checked — no full text of the sourcecites [222] Li H., 2007, J. Phys. Chem. C source

In the paper

“It should be mentioned that as a stabilizer, SA was helpful in protecting the formed nanoparticles, which had a controlled size and shape, as no marked changes in their shape or size were observed during the TEM analysis after heat treatment.”

What the sources say

• ?Not checked — no full text of the sourcecites [207] Jeon T.–Y., 2009, J. Phys. Chem. C source

In the paper

“Plane (111) has the lowest surface energy while plane (110) has the highest.”

What the sources say

• ?Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  cites [273] Yang H., 2008
• ?Not checked — no full text of the sourcecites [274] Bönnemanna H., 2010, Appl. Organometal. Chem. source

In the paper

“Notably, increasing the proportion of the second metal does not monotonically reduce the size of Pt-alloy nanoparticles; their size also often depends on the reaction conditions (e.g., the synthesis method and heat treatment), in addition to the type of second metal and its content.”

In the paper

“Therefore, the degree of alloying can be controlled by adjusting the heat treatment temperature, even though high temperature may increase the particle size.”

In the paper

“In contrast to the shapes of the Pt nanoparticles shown in Figure 12, 12 the shapes of the Pt alloys seem to lack variety, probably because, on the one hand, it is not easy to control particle shape in the synthesis of Pt alloys supported on carbon, and on the other hand, only a few of the expected shapes of Pt alloys can achieve high catalytic activity.”

In the paper

“It was found that when the amount of urea in the starting Pt-salt aqueous solution was increased the size of the Pt complex species decreased, as did that of the metallic Pt nanoparticles”

What the sources say

• ?Not checked — no full text of the sourcecites [4] Fang B., 2009, J. Am. Chem. Soc. source

In the paper

“It was observed that the addition of Fe (at atomic ratios of Pt to Fe from 3:1 to 1:6) could effectively prevent Pt particles from agglomerating and decrease the particle size of Pt-Fe/C from 4.4 to 3.2 nm, based on the Pt (220) diffraction peak in XRD spectra.”

In the paper

“The area-specific ORR activities of Nafion-coated PtM/ C catalysts in O 2 -saturated 0.1 M HClO 4 solution were found to be 1.3 to 1.8 times higher than that of Pt/C, with the ORR activity increasing in the order of Pt/C < PtNi/C < PtFe/C < PtCo/C < PtV/C < PtCr/C.”

What the sources say

• ?Not checked — no full text of the sourcecites [255] Yano H., 2007, Langmuir source

In the paper

“Electrocatalytic activity is shape-dependent, since the electrocatalytic reaction is sensitive to catalyst structure and the reaction rate varies significantly with catalyst shape and/or crystallographic facets.”

What the sources say

• ?Not checked — no full text of the sourcecites [267] Guo D.-J., 2012, Electroanalysis source
• ?Not checked — no full text of the sourcecites [268] Tang Y., 2013, Langmuir source
• ?Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  cites [269] Guo S., 2013, J. Am. Chem. Soc.

In the paper

“Spherical Pd nanocrystals with an average particle size of 4.96 nm were observed in TEM images.”

In the paper

“Novel-shaped nanoparticles often exhibit unique physical and chemical properties.”

In the paper

“Binary Ptbased nanocrystals have been extensively investigated since they are highly tunable and are superior to their monometallic counterparts.[300][301][302]”

What the sources say

• ?Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  cites [300][301][302]

In the paper

“In other words, the morphology of the nanocrystals can be well controlled once a capping agent is selectively adsorbed onto the surface of the metal nanoparticles.272”

What the sources say

• ?Not checked — no full text of the sourcecites [272] Tao A. R., 2008, Small source

In the paper

“Similar to organic capping agents, inorganic ions and other small molecules can also prevent metal nanoparticle size from increasing and affect the shape of formed metal nanoparticles.[313][314][315][316][317][318][319][320]”

What the sources say

• ?Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  cites [313][314][315][316][317][318][319][320]

In the paper

“In recent years, precise shape-controlled Pt-based alloy electrocatalysts have exhibited great potential to deliver superior ORR activity in PEMFCs and thus have become a leading focus of research.”

In the paper

“when hexadecylamine was used as a capping agent, a small portion of cubes was observed (Figure 15a,b) while the use of dodecylamine led to 100% truncated-octahedral nanocrystals of Pt 3 Ni, as shown in Figure 14c.”

What the sources say

• ?Not checked — no full text of the sourcecites [288] Wu J., 2010, J. Am. Chem. Soc. source

In the paper

“Wang et al. reported that a nanocube Pt catalyst was four times more active for the ORR than a Pt nanoparticle, since Pt{111} facets can provide optimal binding energy between platinum atoms and the adsorbed species for ORR.248,341”

What the sources say

• ?Not checked — no full text of the sourcecites [248] Markovic N. M., 1997, J. Electrochem. Soc. source
• ?Not checked — no full text of the sourcecites [341] Wang C., 2008, Angew. Chem., Int. Ed. source

In the paper

“Wu et al. 288 reported truncated-octahedral Pt 3 Ni (t,o-Pt 3 Ni) catalysts with a particle size of 5-7 nm that had a dominant exposure of {111} facets.”

What the sources say

• ?Not checked — no full text of the sourcecites [288] Wu J., 2010, J. Am. Chem. Soc. source

In the paper

“In contrast to the nonhydrolytic system mentioned above, an aqueous solution was used by Shao's group 306 to prepare a sub-10 nm bimetallic core-shell Pd@Pt nanocrystal.”

What the sources say

• ?Not checked — no full text of the sourcecites [306] Zhang G., 2013, J. Phys. Chem. C source

In the paper

“Both chemical and physical templates can offer confined spaces and/or functionalized structures for the formation and growth of a Pt alloy.[327][328][329][330]”

What the sources say

• ?Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  cites [327][328][329][330]

In the paper

“In addition, shaped Pt-based alloy nanostructures often present unusually high catalytic activity.”

In the paper

“Moreover, PVP was found to be suitable only as an alternative reducing agent, while formaldehyde was found to have a negative effect on the formation of regularly shaped PtPd nanocrystals due to the possible strong adsorption of several intermediate chemical species, decomposed from formaldehyde, on the (111) surface.321,322”

What the sources say

• ?Not checked — no full text of the sourcecites [321] Huang X.-Q., 2009, J. Am. Chem. Soc. source
• ?Not checked — no full text of the sourcecites [322] Huang X.-Q., 2011, Nat. Nanotechnol. source

In the paper

“Compared to hard templates, soft templates are more common in actual synthesis because they, especially surfactant molecules, can often provide hydrophilic heads and lipophilic long carbon tails favoring the formation of shape-controlled Pt alloys.”

In the paper

“On the basis of the relationship between shape and facet in Pt-alloy nanocrystals, well-controlled shapes of Pt-based nanocatalysts can not only retain the catalytic property of the bulk metal but also greatly enhance the catalytic activity because the facet can increase the number of Pt active sites.34,148,[341][342][343][344][345]”

What the sources say

• ?Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  cites 34,148,[341][342][343][344][345]

In the paper

“Cheng et al. 335 prepared nest-like Ni 1-x Pt x spheres of submicrometer sizes through a template-replacement route in which poly(styrene-co-methacrylic acid) (PSA) was employed as a soft template.”

What the sources say

• ?Not checked — no full text of the sourcecites [335] Cheng F., 2007, Inorg. Chem. source

In the paper

“It is well-known that organic capping agents play a significant role in the synthesis of shape-controlled colloidal metal nanoparticles.272”

What the sources say

• ?Not checked — no full text of the sourcecites [272] Tao A. R., 2008, Small source

In the paper

“In general, long hydrophobic carbon chains of organic capping agents can provide a steric barrier to prevent direct contact between relatively high energy metallic surfaces and therefore stabilize the metal nanoparticles.”

In the paper

“Typically, inorganic ions such as Br -and I - in a solution of KBr and KI have proven to be as the adsorption/protective agents on the surface of Pt-Pd alloy nanoparticles, favoring the stabilization of the (100) facet and thus the formation of monodispersed sub-10 nm Pt-Pd tetrahedrons and cubes.320”

What the sources say

• ?Not checked — no full text of the sourcecites [320] Yin A.-X., 2011, J. Am. Chem. Soc. source

In the paper

“A capping agent can be selectively adsorbed onto a specific type of facet, since different crystal facets have different atomic arrangement and electronic structures, which bring about the relative growth rates along particular crystallographic directions.”

In the paper

“Since {111} facet has the lowest surface energy among the low-index facets, facecentered cubic (fcc) of crystals always tends to grow along the ⟨100⟩ direction into an octahedron-like shape.”

In the paper

“the total noble mass-specific activity of Pt/Pd 3 Fe/C was about five times larger than that of Pt/C at 0.8 V, as depicted in Figure 18b, while Pt/Pd/C had an enhancement factor of 3.”

In the paper

“Among Pt ML electrocatalysts, those using Pd as the substrate were found to be the most active and durable, 358 exhibiting the highest activity, even higher than Pt (111).351,358”

What the sources say

• ?Not checked — no full text of the sourcecites [358] Sasaki K., 2010, Angew. Chem., Int. Ed. source
• ?Not checked — no full text of the sourcecites [351] Zhang J., 2005, Angew. Chem., Int. Ed. source

In the paper

“The adsorption of CO on {100} facets was found to be stronger than on {111} facets, which favors the formation of the octahedral shape in the synthsis process.”

What the sources say

• ?Not checked — no full text of the sourcecites [287] Wu J., 2011, Nano Lett. source

In the paper

“Also, the bulky 30 nm Pt 3 Ni{111} catalyst showed a 10-fold improvement in ORR activity compared to Pt{111} catalyst and was 90 times more active than current state-of-theart Pt/C catalysts for PEMFCs.”

What the sources say

• ?Not checked — no full text of the sourcecites [147] Stamenkovic V. R., 2007, Science source

In the paper

“Their results showed that the specific activity of the Pt-monolayer catalysts on 4 nm Pd and 4.6 nm Pd 3 Co cores was about 5-and 9-fold enhanced, respectively, over that of 3 nm Pt nanoparticles while only the 2-and 3-fold enhancements in specific activity can be attributed to the nanosize-and lattice mismatch-induced contraction in {111} facets.”

What the sources say

• ?Not checked — no full text of the sourcecites [155] Wang J.-X., 2009, J. Am. Chem. Soc. source

In the paper

“According to their results of XRD and HRTEM, the cubic shape was bound by the {100} facets, while the octahedral shape was bound by {111} facets.”

What the sources say

• ?Not checked — no full text of the sourcecites [287] Wu J., 2011, Nano Lett. source

In the paper

“Kang and Murray 346 showed that the cubic Mn-Pt nanocrystals gave a higher ORR activity than the spherical MnPt nanocrystals in H 2 SO 4 while the spherical nanocrystals were more active in HClO 4 .”

What the sources say

• ?Not checked — no full text of the sourcecites [346] Kang Y., 2010, J. Am. Chem. Soc. source

In the paper

“Importantly, the specific and mass activities of carbon-supported Pt 3 Ni nanooctahedra were found to be ∼7 and ∼4 times, respectively, higher than those of the commercial Pt/C catalysts.”

What the sources say

• ?Not checked — no full text of the sourcecites [286] Zhang J., 2010, Nano Lett. source

In the paper

“Wu et al. 287 utilized CO as a gas reducing agent and made two Pt 3 Ni nanocrystals with octahedral and cubic morphologies.”

What the sources say

• ?Not checked — no full text of the sourcecites [287] Wu J., 2011, Nano Lett. source

In the paper

“This also suggested that the catalytic evaluation of facet-dependent Pt-alloy nanocrystals also depended on the reaction medium, which was in agreement with the results on the catalytic activity of single Pt nanocrystals.347,348”

What the sources say

• ?Not checked — no full text of the sourcecites [347] Markovic N. M., 1995, J. Phys. Chem. source
• ?Not checked — no full text of the sourcecites [348] Guo S., 2013, Angew. Chem., Int. Ed. source

In the paper

“This indicated that the ORR activity of Mn-Pt nanocrystals was higher on {111} facet than on {100} facet in HClO 4 , whereas the ORR activity was higher on {100} facet than on {111} facet in H 2 SO 4 .”

What the sources say

• ?Not checked — no full text of the sourcecites [346] Kang Y., 2010, J. Am. Chem. Soc. source

In the paper

“To make Pt-alloy nanoparticles with predetermined compositions, a strong reducing agentsuch as sodium borohydride, hydrazine, or hydrogenis often introduced to reduce all the metal precursors simultaneously at the proper rates (i.e., coreduction).406,[410][411][412][413][414]”

What the sources say

• ?Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  cites 406,[410][411][412][413][414]

In the paper

“It was found that the core-shell structured PtCo/C catalyst made using the above method had a similar crystallite size (∼2.5 nm) as that of Pt/C catalyst, based on XRD analysis, and its intrinsic activity for the ORR was found to be two to four times higher than that of Pt/C.227”

What the sources say

• ?Not checked — no full text of the sourcecites [227] Kristian N., 2010, Electrochim. Acta source