Size-Dependent Hydrogen Oxidation and Evolution Activities on Supported Palladium Nanoparticles in Acid and Base

Zheng, Jie; Zhou, Shuyuan; Gu, Shuang; Xu, Bingjun; Yan, Yushan

doi:10.1149/2.0661606jes

Cited by 123 publications

(101 citation statements)

References 34 publications

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“…2 According to previous experimental and computational results, conducting ENRR in an alkaline environment could potentially be more selective toward ENRR due to the slower kinetics of the competing HER on the cathode. 18,22,23 Inspired by this, we also investigated the ENRR performance of noble metal catalysts with HEMELs, in which commercial anion exchange membrane and ionomer were employed. Since the possible leaching of quaternary ammonium cations from the membrane and ionomer, which are the typical charge carrying groups for HEMs, could react with the Nessler reagent and interfere the quantification of ammonia from ENRR, it is critical to establish a reliable experimental protocol to separate contributions from ENRR and leaching of HEM and ionomer to the Nessler's results.…”

Section: Resultsmentioning

confidence: 99%

Electrochemical Nitrogen Reduction Reaction on Noble Metal Catalysts in Proton and Hydroxide Exchange Membrane Electrolyzers

Nash

Yang

Anibal

et al. 2017

J. Electrochem. Soc.

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Five noble metal catalysts (Pt/C, Ir/C, Pd/C, Ru/C, and Au/C) are evaluated for electrochemical nitrogen reduction reaction (ENRR) to produce ammonia in both proton exchange membrane (PEM) and hydroxide exchange membrane (HEM) electrolyzers (PEMELs and HEMELs). The competing hydrogen evolution reaction (HER) is found to be the dominant reaction on all catalysts tested in both PEMELS and HEMELs, which is consistent with recent computational predictions that metallic catalysts are unlikely to be selective for ENRR. With the increase of applied potentials, the rate of HER increase significantly, which suppresses the ENRR, leading to significant decreases of faradaic efficiencies. Leaching of quaternary ammonium from HEM is found to interfere with ammonia quantification, which necessitates a pretreatment protocol. Due to the relatively slow kinetics of HER in alkaline solution, faradaic efficiencies in HEMELs are generally higher than those in PEMELs. We believe that these results provide a solid baseline for future research on ENRR in both PEMELs and HEMELs. Ammonia synthesis is one of the foundational chemical processes to the human society, which is estimated to supported approximately 27% of the world's population over the past century.1 The development of the Haber-Bosch process revolutionized modern agriculture, 2 however, the centralized, energy and carbon intensive nature of the Haber-Bosch process 3-5 leaves many aspects to be desired. Distributed and modular ammonia synthesis via the electrochemical nitrogen reduction reaction (ENRR) at or close to ambient conditions, powered by renewable electricity, is an attractive alternative because it allows as-needed production of ammonia, and in turn N-fertilizers, from ubiquitously available resources, i.e., N 2 and water. 4 Widespread adoption of ENRR for ammonia production could drastically reduce the carbon footprint of agricultural activities. In addition, ENRR is compatible with the intermittency of renewable energy sources, e.g., solar and wind, as the ammonia and N-fertilizers can be produced and stored when renewable electricity is available.Electrochemical fixation of atmospheric nitrogen was first attempted in 1908 even before the establishment of the Haber-Bosch process, to make nitric acid via electric discharge. 6 Further studies of ENRR have generally been focused on high temperature proton conductors at 500• C, 7 however, the high operating temperature and the stability of ammonia at such conditions make it unsuitable for distributed deployment. Proton exchange membranes (PEMs) can achieve high proton conductivity (∼100 mS·cm −1 at 25 • C for Nafion) at ambient or slightly elevated temperatures, which opens the possibility for electrochemical ammonia synthesis at those mild conditions. 8 Although Nafion-based low temperature electrochemical ammonia synthesis has been demonstrated in several reports, 9-15 no systematic investigation of noble metal catalysts exists.2 Further, the alkaline environment of hydroxide exchange membranes (HEMs) promises the...

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Section: Resultsmentioning

confidence: 99%

Electrochemical Nitrogen Reduction Reaction on Noble Metal Catalysts in Proton and Hydroxide Exchange Membrane Electrolyzers

Nash

Yang

Anibal

et al. 2017

J. Electrochem. Soc.

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“…However, among PGMs, Pd shows the lowest catalytic activity for HOR in alkaline media: ca. 0.04-0.09 mA cm -2 Pd for commercial Pd/C nanoparticles [18][19][20] vs. ca. 0.6 mA cm -2 Pt for commercial Pt/C catalysts [19][20][21][22].…”

Section: Introductionmentioning

confidence: 99%

Palladium-ceria nanocatalyst for hydrogen oxidation in alkaline media: Optimization of the Pd–CeO2 interface

Davydova

Ash

et al. 2019

Nano Energy

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The development of Pt-free catalyst for anion exchange membrane fuel cells is limited by the sluggish hydrogen oxidation reaction (HOR) at the anode. Previously, the use of CeO2 as a catalyst promoter facilitated drastic ennoblement of Pd for the HOR kinetics in base media. However, further optimization and understanding of the Pd-CeO2 interaction, surface properties, and its influence on HOR are still needed. In this work, three types of Pd-CeO2/C catalysts are synthesized by a flame-based process, where the Pd-CeO2 interface and HOR activity are improved as compared to catalysts prepared by wet-chemistry processes. The correlation between the Pd-CeO2 interaction and HOR activity is established through comparisons with the three types of Pd-CeO2/C synthesized catalysts using electrochemical techniques and X-ray photoelectron spectroscopy.

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“…As for metal catalysts with different sizes, their coordinative and electronic properties are often different from each other. For example, small metal clusters with a large part of coordinative unsaturated sites usually have stronger interaction energy with molecules than that of their larger counterparts [ 9 , 10 ]. According to the Sabatier principle [ 11 ], the optimum catalytic performance can be achieved with a medium interaction energy such that volcano-shaped size-performance relationships would be observed in many heterogeneous catalytic reactions [ 12 – 16 ].…”

Section: Introductionmentioning

confidence: 99%

Carbon Monoxide Promotes the Catalytic Hydrogenation on Metal Cluster Catalysts

et al. 2020

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Size effect plays a crucial role in catalytic hydrogenation. The highly dispersed ultrasmall clusters with a limited number of metal atoms are one candidate of the next generation catalysts that bridge the single-atom metal catalysts and metal nanoparticles. However, for the unfavorable electronic property and their interaction with the substrates, they usually exhibit sluggish activity. Taking advantage of the small size, their catalytic property would be mediated by surface binding species. The combination of metal cluster coordination chemistry brings new opportunity. CO poisoning is notorious for Pt group metal catalysts as the strong adsorption of CO would block the active centers. In this work, we will demonstrate that CO could serve as a promoter for the catalytic hydrogenation when ultrasmall Pd clusters are employed. By means of DFT calculations, we show that Pdn n=2‐147 clusters display sluggish activity for hydrogenation due to the too strong binding of hydrogen atom and reaction intermediates thereon, whereas introducing CO would reduce the binding energies of vicinal sites, thus enhancing the hydrogenation reaction. Experimentally, supported Pd2CO catalysts are fabricated by depositing preestablished [Pd2(μ-CO)2Cl4]2- clusters on oxides and demonstrated as an outstanding catalyst for the hydrogenation of styrene. The promoting effect of CO is further verified experimentally by removing and reintroducing a proper amount of CO on the Pd cluster catalysts.

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Size-Dependent Hydrogen Oxidation and Evolution Activities on Supported Palladium Nanoparticles in Acid and Base

Cited by 123 publications

References 34 publications

Electrochemical Nitrogen Reduction Reaction on Noble Metal Catalysts in Proton and Hydroxide Exchange Membrane Electrolyzers

Electrochemical Nitrogen Reduction Reaction on Noble Metal Catalysts in Proton and Hydroxide Exchange Membrane Electrolyzers

Palladium-ceria nanocatalyst for hydrogen oxidation in alkaline media: Optimization of the Pd–CeO2 interface

Carbon Monoxide Promotes the Catalytic Hydrogenation on Metal Cluster Catalysts

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