Chemical Dealloying Mechanism of Bimetallic Pt–Co Nanoparticles and Enhancement of Catalytic Activity toward Oxygen Reduction

Lai, Feng‐Ju; Su, Wei‐Nien; Sarma, Loka Subramanyam; Liu, Din‐Goa; Hsieh, Cheng-An; Lee, Jyh‐Fu; Hwang, Bing‐Joe

doi:10.1002/chem.200902263

Cited by 100 publications

(71 citation statements)

References 42 publications

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“…Here, it would appear that the direction of the charge transfer is not completely determined by the electronegativity difference of the two metals. Similar findings were also reported by other groups, such as charge transfer from Au to Pt [596,597], and charge transfer from Co to Pt [598]. These results demonstrate the importance of ligand effects on both precious and non-precious metal cores in the chemical properties of the shell.…”

Section: Electronic Effectsupporting

confidence: 91%

Core–Shell-Structured Low-Platinum Electrocatalysts for Fuel Cell Applications

Wang

Luo

et al. 2018

Electrochem. Energ. Rev.

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Pt-based catalysts are the most efficient catalysts for low-temperature fuel cells. However, commercialization is impeded by prohibitively high costs and scarcity. One of the most effective strategies to reduce Pt loading is to deposit a monolayer or a few layers of Pt over other metal cores to form core-shell-structured electrocatalysts. In core-shell-structured electrocatalysts, the compositions of the core can be divided into five classes: single-precious metallic cores represented by Pd, Ru, and Au; singlenon-precious metallic cores represented by Cu, Ni, Co, and Fe; alloy cores containing 3d, 4d or 5d metals; and carbide and nitride cores. Of these, researchers have found that carbide and nitride cores can yield tremendous advantages over alloy cores in terms of cost and promotional activities of Pt shells. In addition, desirable shells with reasonable thicknesses and compositions have been recognized to play a dominant role in electrocatalytic performances. And recently, researchers have also found that the catalytic activity of core-shell-structured catalysts is dependent on the binding energy of the adsorbents, which is determined by the d-band center of Pt. The shifting of this d-band center in turn is mainly affected by strain and electronic effects, which can be adjusted by adjusting core compositions and shell thicknesses of catalysts. In the development of these core-shell structures, optimal synthesis methods are of primary concern because they directly determine the practical application potential of the resulting electrocatalysts. And in this article, the principles behind core-shell-structured low-Pt electrocatalysts and the developmental progresses of various synthesis methods along with the traits of each type of core and its effects on Pt shell catalytic activities are discussed. In addition, perspectives on this type of catalyst are discussed and future research directions are proposed.

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Section: Electronic Effectsupporting

confidence: 91%

Core–Shell-Structured Low-Platinum Electrocatalysts for Fuel Cell Applications

Wang

Luo

et al. 2018

Electrochem. Energ. Rev.

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“…The high specific surface area of this kind of material confers them exceptional properties such as super-hydrophobicity [1,2], enhanced catalysis activity [3][4][5][6], and very selective filtering ability [7,8]. Various materials were used to synthesize nanoporous structures including metals (e.g., Au [6,[9][10][11][12][13][14], Pt [15][16][17][18], and Ag [19,20]), oxides (e.g., TiO 2 [21][22][23] and SiO 2 [24,25]) and carbon [26][27][28][29][30][31][32][33][34][35][36]. In general, the material forming the skeleton of the nanoporous structure is selected according to the aimed application.…”

Section: Introductionmentioning

confidence: 99%

“…It should be noted that the means of control of the pore characteristics depend on both the strategy used to create the porosity within the material and the considered material itself. For example, to create nanoporous metals, ''dealloying'' is the most popular method which has been developed so far [9,11,12,16,19,45,[49][50][51][52][53][54][55][56]. This approach consists in removing one of two alloyed metals using a selective corrosion process [54,57].…”

Section: Introductionmentioning

confidence: 99%

“…However, to ensure a preferential etching, the oxidation potentials of the two selected metals forming the initial alloy must be very different, where the metal with the lower oxidation potential will be etched selectively leaving behind the more noble one. In general, the dealloying method is employed to create porous noble metals (Pd [49], Pt [15][16][17]45], and Au [9,11,12,51,58]) exhibiting very high oxidation potentials compared to other metals used in the alloys such as Ag, Co and Cu. The phenomena occurring during the dealloying process (e.g., dissolution of the less noble metal atoms, surface diffusion of the more noble metal, strains generation, etc.…”

Section: Introductionmentioning

confidence: 99%

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Sponge-like carbon thin films: The dealloying concept applied to copper/carbon nanocomposite

Bouts

Mel

Angleraud

2015

Carbon

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“…4a. The annealed PtCo 2 Ni 2 /C catalysts show the broaden peaks in the hydrogen adsorption region between 0−0.4 V compared with Pt/C, which is due to the shift of the d-band center of the surface Pt atoms after alloying with Co and Ni [22,31,50] and thus a weakened interaction between Pt and intermediate oxide species, releasing more active sites for O 2 adsorption [51]. In the case of ORR, the coverage of the adsorbed hydroxyl species (OH ad ) on the surface active sites will inhibit the O 2 adsorption and hinder the reaction.…”

Section: Lettersmentioning

confidence: 98%

Carbon-supported PtCo2Ni2 alloy with enhanced activity and stability for oxygen reduction

Gao

et al. 2015

Sci. China Mater.

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The commercialization of proton exchange membrane fuel cells (PEMFCs) is still restricted by the well-known dilemma, that is, the heavy dependence of using expensive plantinum (Pt) catalyst to negotiate the sluggish oxygen reduction reaction (ORR) kinetics in fuel cell cathodes. Here, a carbon-supported PtCo2Ni2 alloy catalyst with low Pt usage was synthesized via a simple method, which exhibited exceptional ORR activity with a more positive half-wave potential (E1/2) ~57 mV, which was more positive than the state-of-the-art Pt/C catalysts. Moreover, the alloy catalyst performs excellent durability after 10,000 harsh cycles compared with that of Pt/C catalyst in acidic solution, which may be developed as a promising alternative for Ptbased catalysts in fuel cell technology.Proton exchange membrane fuel cells (PEMFCs) have drawn intensive attention as promising candidates for nonpolluting and high-efficiency energy conversion in automotive and portable power [1−3]. However, large-scale commercialization of this technology is greatly hindered by the heavy dependence of using rare Pt as electrocatalysts [4−7]. Considerable efforts have been devoted to developing alternative Pt-free electrocatalysts, while Pt is still the most effective oxygen reduction reaction (ORR) catalyst, especially in acidic environment [8−14]. Therefore, to make PEMFCs economically competitive, an effective way is to develop composition and surface tunable Pt-based alloy catalysts with low cost, high activity and durability [15−20].Recently, a number of studies demonstrated that Ptbased multimetallic electrocatalysts (alloyed with Ni, Co, Fe, Cu, etc.) with altered surface electronic structure would exhibit high catalytic activity for the ORR [21−34]. Recently, our research on Pt-based binary and ternary electrocatalysts revealed that excellent catalytic activity for ORR, fo rmic acid oxidation, and methanol oxidation could be achieved by alloying Pt with other cheaper transition elements such as Pd, Ni, and Cu by taking advantages of the altered electronic structure of Pt and the favorable surface composition of the alloy electrocatalyst [18,21,24,35,36]. For instance, a mixed PtPd alloy surface could be obtained by surface atomic redistribution of ternary PtPdCu upon potential cycling in an acidic electrolyte, and the distinctive topmost layer played a key role in the enhancement of catalytic activity [35]. Moreover, we found that mixed-PtPdshell ternary PtPdCu nanoparticle nanotubes also showed significant enhancement for ORR by using copper nanowires as templates [18]. The c ore/shell Pd/PtFe catalysts also show improved ORR activity and durability, which is highly associated with the FePt shell thickness [37]. It is believed that the arrangement of composition of the topmost layer, and rationally introducing foreign metals to modify the electronic structure of Pt are critical factors to enhance the electrochemical performance of Pt-based ORR catalysts [38].On the other hand, carbon support technology has been verified to be an effective...

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Chemical Dealloying Mechanism of Bimetallic Pt–Co Nanoparticles and Enhancement of Catalytic Activity toward Oxygen Reduction

Cited by 100 publications

References 42 publications

Core–Shell-Structured Low-Platinum Electrocatalysts for Fuel Cell Applications

Core–Shell-Structured Low-Platinum Electrocatalysts for Fuel Cell Applications

Sponge-like carbon thin films: The dealloying concept applied to copper/carbon nanocomposite

Carbon-supported PtCo2Ni2 alloy with enhanced activity and stability for oxygen reduction

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