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Promoting Effect of Cu on Pd Applied to the Hydrazine Electro-Oxidation and Direct Hydrazine Fuel Cells. Catalysts 2022. [DOI: 10.3390/catal12121639] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Use of liquid fuels in fuel cells is advantageous due to the easier and safer handling, transportation, and storage. Among the different options, hydrazine is of interest since the formation of highly poisoning carbonaceous species is avoided, in addition to its high energy density. In the search for more active direct hydrazine fuel cells (DHFC), this study analyzes the influence of Cu as an auxiliary metal on Pd. Three different PdxCu/C (x = 3, 1, and 0.33) catalysts were prepared by chemical reduction with NaBH4. The materials were physiochemically characterized by X-ray diffraction, energy-dispersive X-ray spectroscopy, transmission electron microscopy, and X-ray photoelectron spectroscopy. Electrochemical analysis in a three-electrode glass cell and a single-cell DHFC was also carried out to study the impact on the electroactivity. Cu exerts a beneficial effect by reducing the adsorption energies of the adsorbed species and donating oxidized species for the completion of the hydrazine electro-oxidation, optimally balanced in the Pd1Cu/C (maximum power density of 180 mW cm−2). As a counterpoint, Cu slightly promotes the non-faradaic decomposition of hydrazine, seen by a larger H2 signal in mass spectroscopy in the anode exhaust at high current densities, which results in a slight loss in faradaic efficiency.
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Xie W, Zhang G, Guo Z, Huang H, Ye J, Gao X, Yue K, Wei Y, Zhao L. Shape-controllable and kinetically miscible Copper-Palladium bimetallic nanozymes with enhanced Fenton-like performance for biocatalysis. Mater Today Bio 2022; 16:100411. [PMID: 36186845 PMCID: PMC9520275 DOI: 10.1016/j.mtbio.2022.100411] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2022] [Revised: 08/23/2022] [Accepted: 08/24/2022] [Indexed: 12/03/2022] Open
Abstract
Bimetallic nanozymes have been emerging as essential catalysts due to their unique physicochemical properties from the monometallics. However, the access to optimize catalytic performance is often limited by the thermodynamic immiscibility and also heterogeneity. Thus, we present a one-step coreduction strategy to prepare the miscible Cu–Pd bimetallic nanozymes with controllable shape and homogeneously alloyed structure. The homogeneity is systematically explored and luckily, the homogeneous introduction of Cu successfully endows Cu–Pd bimetallic nanozymes with enhanced Fenton-like efficiency. Density functional theory (DFT) theoretical calculation reveals that Cu–Pd bimetallic nanozymes exhibit smaller d-band center compared with Pd nanozymes. Easier adsorption of H2O2 molecular contributed by the electronic structure of Cu significantly accelerate the catalytic process together with the strong repulsive interaction between H atom and Pd atom. In vitro cytotoxicity and intracellular ROS generation performance reveal the potential for in vivo biocatalysis. The strategy to construct kinetically miscible Cu–Pd bimetallic nanozymes will guide the development of bimetallic catalysts with excellent Fenton-like efficiency for biocatalytic nanomedicine.
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Affiliation(s)
- Wensheng Xie
- The Key Laboratory of Bioorganic Phosphorus Chemistry & Chemical Biology (Ministry of Education), Department of Chemistry, Tsinghua University, Beijing 100084, PR China
| | - Genpei Zhang
- School of Energy and Environmental Engineering, University of Science and Technology Beijing, Beijing 100083, PR China.,Shunde Graduate School of University of Science and Technology Beijing, Shunde, Guangdong Province, 528399, PR China
| | - Zhenhu Guo
- State Key Laboratory of New Ceramics and Fine Processing, School of Materials Science and Engineering, Tsinghua University, Beijing 100084, PR China
| | - Hongye Huang
- The Key Laboratory of Bioorganic Phosphorus Chemistry & Chemical Biology (Ministry of Education), Department of Chemistry, Tsinghua University, Beijing 100084, PR China
| | - Jielin Ye
- State Key Laboratory of New Ceramics and Fine Processing, School of Materials Science and Engineering, Tsinghua University, Beijing 100084, PR China
| | - Xiaohan Gao
- State Key Laboratory of New Ceramics and Fine Processing, School of Materials Science and Engineering, Tsinghua University, Beijing 100084, PR China
| | - Kai Yue
- School of Energy and Environmental Engineering, University of Science and Technology Beijing, Beijing 100083, PR China.,Shunde Graduate School of University of Science and Technology Beijing, Shunde, Guangdong Province, 528399, PR China
| | - Yen Wei
- The Key Laboratory of Bioorganic Phosphorus Chemistry & Chemical Biology (Ministry of Education), Department of Chemistry, Tsinghua University, Beijing 100084, PR China
| | - Lingyun Zhao
- State Key Laboratory of New Ceramics and Fine Processing, School of Materials Science and Engineering, Tsinghua University, Beijing 100084, PR China
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3
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Li XQ, Duan GY, Yang XX, Han LJ, Xu BH. Electroreduction of carbon dioxide to multi-electron reduction products using poly(ionic liquid)-based Cu-Pd catalyst. FUNDAMENTAL RESEARCH 2022; 2:937-945. [PMID: 38933384 PMCID: PMC11197817 DOI: 10.1016/j.fmre.2021.12.009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2021] [Revised: 12/18/2021] [Accepted: 12/21/2021] [Indexed: 10/19/2022] Open
Abstract
Electrocatalytic reduction of CO2 (CO2RR) to multi-electron (> 2e-) products provides a green and sustainable route for producing fuels and chemicals. Introducing the second metal element is a feasible strategy for "managing" the key intermediate on Cu-based materials to further improve the CO2RR catalytic performance. In this work, palladium, which promises the generation of CO, was introduced into the poly(ionic liquid)-based copper hybrid (Cu@PIL) to construct a novel Cu-Pd bimetallic electrocatalyst (Cu@PIL@Pd). Remarkably, with a small dosage of palladium (2.0 mol% compared with Cu), a high faradaic efficiency (FE) for C2+ products (68.7%) was achieved at -1.01 V (with respect to the reversible hydrogen electrode (RHE), the same below) with a high partial current density of 178.3 mA cm-2. Meanwhile, high selectivity towards CH4 (FE = 42.5%) and corresponding partial current density of 172.8 mA cm-2 were obtained on the same catalyst at -1.24 V, signifying a significant potential-dependent selectivity. Mechanistic studies reveal that both copper and palladium oxides are reduced to metallic states during the CO2RR. The presence of the adjoint copper phase and the highly dispersed electrostatic layer promote the generation of CO on the palladium components (both the PdO2 phase and the Pd(II) site). Besides, the local CO* was enriched by the significant diffusion resistance of CO in the PIL layer. The spillover of CO* from Pd sites to the adjoint Cu sites, accompanied by the increased local concentration of CO* around Cu sites, accounted for the observed good CO2RR catalytic performance, especially the high C2+ product selectivity.
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Affiliation(s)
- Xiao-Qiang Li
- Beijing Key Laboratory of Ionic Liquids Clean Process, CAS Key Laboratory of Green Process and Engineering, State Key Laboratory of Multiphase Complex Systems, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190, China
- School of Chemical Engineering, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Guo-Yi Duan
- Beijing Key Laboratory of Ionic Liquids Clean Process, CAS Key Laboratory of Green Process and Engineering, State Key Laboratory of Multiphase Complex Systems, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190, China
| | - Xian-Xia Yang
- National Fundamental Research Laboratory of New Hazardous Chemicals Assessment and Accident Analysis, Institute of Applied Electrochemistry, Beijing University of Chemical Technology, Beijing 100029, China
| | - Li-Jun Han
- Beijing Key Laboratory of Ionic Liquids Clean Process, CAS Key Laboratory of Green Process and Engineering, State Key Laboratory of Multiphase Complex Systems, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190, China
| | - Bao-Hua Xu
- Beijing Key Laboratory of Ionic Liquids Clean Process, CAS Key Laboratory of Green Process and Engineering, State Key Laboratory of Multiphase Complex Systems, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100190, China
- School of Chemical Engineering, University of Chinese Academy of Sciences, Beijing 100049, China
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Liu S, Li Y, Yu X, Han S, Zhou Y, Yang Y, Zhang H, Jiang Z, Zhu C, Li WX, Wöll C, Wang Y, Shen W. Tuning crystal-phase of bimetallic single-nanoparticle for catalytic hydrogenation. Nat Commun 2022; 13:4559. [PMID: 35931670 PMCID: PMC9355964 DOI: 10.1038/s41467-022-32274-4] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2022] [Accepted: 07/22/2022] [Indexed: 11/09/2022] Open
Abstract
Bimetallic nanoparticles afford geometric variation and electron redistribution via strong metal-metal interactions that substantially promote the activity and selectivity in catalysis. Quantitatively describing the atomic configuration of the catalytically active sites, however, is experimentally challenged by the averaging ensemble effect that is caused by the interplay between particle size and crystal-phase at elevated temperatures and under reactive gases. Here, we report that the intrinsic activity of the body-centered cubic PdCu nanoparticle, for acetylene hydrogenation, is one order of magnitude greater than that of the face-centered cubic one. This finding is based on precisely identifying the atomic structures of the active sites over the same-sized but crystal-phase-varied single-particles. The densely-populated Pd-Cu bond on the chemically ordered nanoparticle possesses isolated Pd site with a lower coordination number and a high-lying valence d-band center, and thus greatly expedites the dissociation of H2 over Pd atom and efficiently accommodates the activated H atoms on the particle top/subsurfaces.
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Affiliation(s)
- Shuang Liu
- State Key Laboratory of Catalysis, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, China
| | - Yong Li
- State Key Laboratory of Catalysis, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, China.
| | - Xiaojuan Yu
- Institute of Functional Interfaces, Karlsruhe Institute of Technology, Eggenstein-Leopoldshafen, Germany
| | - Shaobo Han
- State Key Laboratory of Catalysis, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, China
| | - Yan Zhou
- State Key Laboratory of Catalysis, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, China
| | - Yuqi Yang
- Shanghai Synchrotron Radiation Facility, Shanghai Advanced Research Institute, Chinese Academy of Sciences, Shanghai, China
| | - Hao Zhang
- Shanghai Synchrotron Radiation Facility, Shanghai Advanced Research Institute, Chinese Academy of Sciences, Shanghai, China
| | - Zheng Jiang
- Shanghai Synchrotron Radiation Facility, Shanghai Advanced Research Institute, Chinese Academy of Sciences, Shanghai, China.
| | - Chuwei Zhu
- School of Chemistry and Materials Science, Hefei National Research Center for Physical Sciences at the Microscale, University of Science and Technology of China, Hefei, China
| | - Wei-Xue Li
- School of Chemistry and Materials Science, Hefei National Research Center for Physical Sciences at the Microscale, University of Science and Technology of China, Hefei, China
| | - Christof Wöll
- Institute of Functional Interfaces, Karlsruhe Institute of Technology, Eggenstein-Leopoldshafen, Germany
| | - Yuemin Wang
- Institute of Functional Interfaces, Karlsruhe Institute of Technology, Eggenstein-Leopoldshafen, Germany.
| | - Wenjie Shen
- State Key Laboratory of Catalysis, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, China.
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Zeng S, Shan S, Lu A, Wang S, Caracciolo DT, Robinson RJ, Shang G, Xue L, Zhao Y, Zhang A, Liu Y, Liu S, Liu Z, Bai F, Wu J, Wang H, Zhong CJ. Copper-alloy catalysts: structural characterization and catalytic synergies. Catal Sci Technol 2021. [DOI: 10.1039/d1cy00179e] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Recent progress in the development of copper-alloy catalysts is highlighted, focusing on the structural and mechanistic characterizations of the catalysts in different catalytic reactions, and challenges and opportunities in future research.
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Affiliation(s)
- Shanghong Zeng
- Inner Mongolia Key Laboratory of Chemistry and Physics of Rare Earth Materials, School of Chemistry and Chemical Engineering, Inner Mongolia University, Hohhot, Inner Mongolia 010021, P.R. China
- Department of Chemistry, State University of New York at Binghamton, Binghamton, NY 13902, USA
| | - Shiyao Shan
- Department of Chemistry, State University of New York at Binghamton, Binghamton, NY 13902, USA
| | - Aolin Lu
- Department of Chemistry, State University of New York at Binghamton, Binghamton, NY 13902, USA
| | - Shan Wang
- Department of Chemistry, State University of New York at Binghamton, Binghamton, NY 13902, USA
| | - Dominic T. Caracciolo
- Department of Chemistry, State University of New York at Binghamton, Binghamton, NY 13902, USA
| | - Richard J. Robinson
- Department of Chemistry, State University of New York at Binghamton, Binghamton, NY 13902, USA
| | - Guojun Shang
- Department of Chemistry, State University of New York at Binghamton, Binghamton, NY 13902, USA
| | - Lei Xue
- Inner Mongolia Key Laboratory of Chemistry and Physics of Rare Earth Materials, School of Chemistry and Chemical Engineering, Inner Mongolia University, Hohhot, Inner Mongolia 010021, P.R. China
| | - Yuansong Zhao
- Inner Mongolia Key Laboratory of Chemistry and Physics of Rare Earth Materials, School of Chemistry and Chemical Engineering, Inner Mongolia University, Hohhot, Inner Mongolia 010021, P.R. China
| | - Aiai Zhang
- Inner Mongolia Key Laboratory of Chemistry and Physics of Rare Earth Materials, School of Chemistry and Chemical Engineering, Inner Mongolia University, Hohhot, Inner Mongolia 010021, P.R. China
| | - Yang Liu
- Inner Mongolia Key Laboratory of Chemistry and Physics of Rare Earth Materials, School of Chemistry and Chemical Engineering, Inner Mongolia University, Hohhot, Inner Mongolia 010021, P.R. China
| | - Shangpeng Liu
- Inner Mongolia Key Laboratory of Chemistry and Physics of Rare Earth Materials, School of Chemistry and Chemical Engineering, Inner Mongolia University, Hohhot, Inner Mongolia 010021, P.R. China
| | - Ze Liu
- Inner Mongolia Key Laboratory of Chemistry and Physics of Rare Earth Materials, School of Chemistry and Chemical Engineering, Inner Mongolia University, Hohhot, Inner Mongolia 010021, P.R. China
| | - Fenghua Bai
- Inner Mongolia Key Laboratory of Chemistry and Physics of Rare Earth Materials, School of Chemistry and Chemical Engineering, Inner Mongolia University, Hohhot, Inner Mongolia 010021, P.R. China
| | - Jinfang Wu
- Inner Mongolia Key Laboratory of Chemistry and Physics of Rare Earth Materials, School of Chemistry and Chemical Engineering, Inner Mongolia University, Hohhot, Inner Mongolia 010021, P.R. China
| | - Hong Wang
- School of Chemical Engineering, Inner Mongolia University of Technology, Hohhot, Inner Mongolia, 010051, P.R. China
| | - Chuan-Jian Zhong
- Department of Chemistry, State University of New York at Binghamton, Binghamton, NY 13902, USA
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Monometallic and bimetallic catalysts based on Pd, Cu and Ni for hydrogen transfer deoxygenation of a prototypical fatty acid to diesel range hydrocarbons. Catal Today 2020. [DOI: 10.1016/j.cattod.2019.03.017] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Zhao Z, Xu H, Gao Y, Cheng D. Universal description of heating-induced reshaping preference of core-shell bimetallic nanoparticles. NANOSCALE 2019; 11:1386-1395. [PMID: 30604829 DOI: 10.1039/c8nr08889f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
To achieve universal description of the reshaping process of core-shell bimetallic nanoparticles, we combined the tight-binding Ising Hamiltonian model with molecular dynamic simulations to propose a general theoretical model at the atomic scale while considering the temperature, bond energy, atomic size, and surface energy effects. Based on this model, we can quantitatively analyze the tendency of core-shell structured bimetallic nanoparticles toward the reshaping phenomenon upon heating. By rapidly screening 196 types of bimetallic nanoparticles (containing transition metal elements from VIII to IIB groups in the fourth, fifth, and sixth rows of the periodic table), we identified forty-four kinds of bimetallic nanoparticles with reshaping tendency upon heating, which was validated by molecular dynamic simulations and available experimental results. With increasing temperature, the bimetallic nanoparticles with reshaping preference were transformed from an icosahedron to a star-like shape. In contrast, the structure of bimetallic nanoparticles without reshaping preference was transformed from an icosahedron to a sphere shape, which is usually considered to be the normal pre-melting phenomenon. Further structural analysis indicated that the reshaping of bimetallic nanoparticles could be ascribed to different diffusion mechanisms, where a dominant unidirectional mechanism leads to reshaped bimetallic nanoparticles and a bidirectional diffusion mechanism results in no-reshaped bimetallic nanoparticles. This study provides a deep insight into the origin of reshaping in bimetallic nanoparticles, and it may stimulate extensive studies on engineering bimetallic nanoparticles to switch on/off reshaping upon heating, for example, by modifying the structures, atomic arrangement or composites of bimetallic systems in future.
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Affiliation(s)
- Zheng Zhao
- State Key Laboratory of Organic-Inorganic Composites, Beijing Key Laboratory of Energy Environmental Catalysis, Beijing University of Chemical Technology, Beijing 100029, China.
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Kareem H, Shan S, Lin F, Li J, Wu Z, Prasai B, O'Brien CP, Lee IC, Tran DT, Yang L, Mott D, Luo J, Petkov V, Zhong CJ. Evolution of surface catalytic sites on thermochemically-tuned gold-palladium nanoalloys. NANOSCALE 2018; 10:3849-3862. [PMID: 29417115 DOI: 10.1039/c7nr08748a] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Nanoscale alloying constitutes an increasingly-important pathway for design of catalysts for a wide range of technologically important reactions. A key challenge is the ability to control the surface catalytic sites in terms of the alloying composition, thermochemical treatment and phase in correlation with the catalytic properties. Herein we show novel findings of the nanoscale evolution of surface catalytic sites on thermochemically-tuned gold-palladium nanoalloys by probing CO adsorption and oxidation using in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) technique. In addition to the bimetallic composition and the support, the surface sites are shown to depend strongly on the thermochemical treatment condition, demonstrating that the ratio of three-fold vs. bridge or atop Pd sites is greatly reduced by thermochemical treatment under hydrogen in comparison with that under oxygen. This type of surface reconstruction is further supported by synchrotron high-energy X-ray diffraction coupled to atomic pair distribution function (HE-XRD/PDF) analysis of the nanoalloy structure, revealing an enhanced degree of random alloying for the catalysts thermochemically treated under hydrogen. The nanoscale alloying and surface site evolution characteristics were found to correlate strongly with the catalytic activity of CO oxidation. These findings have significant implications for the nanoalloy-based design of catalytic synergy.
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Affiliation(s)
- Haval Kareem
- Department of Chemistry, State University of New York at Binghamton, Binghamton, NY 13902, USA.
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Shan S, Petkov V, Prasai B, Wu J, Joseph P, Skeete Z, Kim E, Mott D, Malis O, Luo J, Zhong CJ. Catalytic activity of bimetallic catalysts highly sensitive to the atomic composition and phase structure at the nanoscale. NANOSCALE 2015; 7:18936-18948. [PMID: 26404795 DOI: 10.1039/c5nr04535e] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
The ability to determine the atomic arrangement in nanoalloy catalysts and reveal the detailed structural features responsible for the catalytically active sites is essential for understanding the correlation between the atomic structure and catalytic properties, enabling the preparation of efficient nanoalloy catalysts by design. Herein we describe a study of CO oxidation over PdCu nanoalloy catalysts focusing on gaining insights into the correlation between the atomic structures and catalytic activity of nanoalloys. PdCu nanoalloys of different bimetallic compositions are synthesized as a model system and are activated by a controlled thermochemical treatment for assessing their catalytic activity. The results show that the catalytic synergy of Pd and Cu species evolves with both the bimetallic nanoalloy composition and temperature of the thermochemical treatment reaching a maximum at a Pd : Cu ratio close to 50 : 50. The nanoalloys are characterized structurally by ex situ and in situ synchrotron X-ray diffraction, including atomic pair distribution function analysis. The structural data show that, depending on the bimetallic composition and treatment temperature, PdCu nanoalloys adopt two different structure types. One features a chemically ordered, body centered cubic (B2) type alloy consisting of two interpenetrating simple cubic lattices, each occupied with Pd or Cu species alone, and the other structure type features a chemically disordered, face-centered cubic (fcc) type of alloy wherein Pd and Cu species are intermixed at random. The catalytic activity for CO oxidation is strongly influenced by the structural features. In particular, it is revealed that the prevalence of chemical disorder in nanoalloys with a Pd : Cu ratio close to 50 : 50 makes them superior catalysts for CO oxidation in comparison with the same nanoalloys of other bimetallic compositions. However, the catalytic synergy can be diminished if the Pd50Cu50 nanoalloys undergo phase segregation into distinct chemically-ordered (B2-type) and disordered (fcc-type) domains. This finding is significant since it provides a rational basis for streamlining the design and preparation of Pd-based nanoalloy catalysts in terms of atomic structure and phase state.
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Affiliation(s)
- Shiyao Shan
- Department of Chemistry, State University of New York at Binghamton, Binghamton, NY 13902, USA.
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Wu J, Shan S, Luo J, Joseph P, Petkov V, Zhong CJ. PdCu Nanoalloy Electrocatalysts in Oxygen Reduction Reaction: Role of Composition and Phase State in Catalytic Synergy. ACS APPLIED MATERIALS & INTERFACES 2015; 7:25906-25913. [PMID: 26569372 DOI: 10.1021/acsami.5b08478] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
The catalytic synergy of nanoalloy catalysts depends on the nanoscale size, composition, phase state, and surface properties. This report describes findings of an investigation of their roles in the enhancement of electrocatalytic activity of PdCu alloy nanoparticle catalysts for oxygen reduction reaction (ORR). Pd(n)Cu(100-n) nanoalloys with controlled composition and subtle differences in size and phase state were synthesized by two different wet chemical methods. Detailed electrochemical characterization was performed to determine the surface properties and the catalytic activities. The atomic-scale structures of these catalysts were also characterized by high-energy synchrotron X-ray diffraction coupled with atomic pair distribution function analysis. The electrocatalytic activity and stability were shown to depend on the size, composition, and phase structure. With Pd(n)Cu(100-n) catalysts from both methods, a maximum ORR activity was revealed at Pd/Cu ratio close to 50:50. Structurally, Pd50Cu50 nanoalloys feature a mixed phase consisting of chemically ordered (body-centered cubic type) and disordered (face-centered cubic type) domains. The phase-segregated structure is shown to change to a single phase upon electrochemical potential cycling in ORR condition. While the surface Cu dissolution occurred in PdCu catalysts from the two different synthesis methods, the PdCu with a single-phase character is found to exhibit a tendency of a much greater dissolution than that with the phase segregation. Analysis of the results, along theoretical modeling based on density functional theory calculation, has provided new insights for the correlation between the electrocatalytic activity and the catalyst structures.
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Affiliation(s)
- Jinfang Wu
- Department of Chemistry and Chemical Engineering, Chongqing University , Chongqing 400030, China
- Department of Chemistry, State University of New York at Binghamton , Binghamton, New York13902, United States
| | - Shiyao Shan
- Department of Chemistry, State University of New York at Binghamton , Binghamton, New York13902, United States
| | - Jin Luo
- Department of Chemistry, State University of New York at Binghamton , Binghamton, New York13902, United States
| | - Pharrah Joseph
- Department of Chemistry, State University of New York at Binghamton , Binghamton, New York13902, United States
| | - Valeri Petkov
- Department of Physics, Central Michigan University , Mt. Pleasant, Michigan 48859, United States
| | - Chuan-Jian Zhong
- Department of Chemistry, State University of New York at Binghamton , Binghamton, New York13902, United States
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