Operando Surface X-ray Diffraction Studies of Structurally Defined Co3O4 and CoOOH Thin Films during Oxygen Evolution

Reikowski, Finn; Maroun, Fouad; Pacheco, Ivan; Wiegmann, Tim; Allongue, P.; Stettner, J.; Magnussen, Olaf M.

doi:10.1021/acscatal.8b04823

Cited by 112 publications

(152 citation statements)

References 60 publications

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“…[16,44,50] Further characterization of phases, coordination numbers (CN) and interatomic distances (R) can be performed by X-ray absorption spectroscopy (XAS) [51][52][53][54][55] and X-ray diffraction. [56][57][58][59][60] X-ray photoelectron spectroscopy (XPS) yields information on catalyst (surface) composition and adsorbed species. [61][62][63][64][65][66] The same holds for infrared spectroscopy (Fourier transform (FT) IR), [20,24,60,[67][68][69][70][71][72][73][74][75][76] but the its focus is clearly on vibrations of adsorbed reactant/intermediate/spectator/product molecules.…”

Section: Introductionmentioning

confidence: 99%

“…[61][62][63][64][65][66] The same holds for infrared spectroscopy (Fourier transform (FT) IR), [20,24,60,[67][68][69][70][71][72][73][74][75][76] but the its focus is clearly on vibrations of adsorbed reactant/intermediate/spectator/product molecules. For brevity, XRD [56][57][58][59][60] and Raman spectroscopy [77][78][79][80][81] are not discussed in here, despite their importance.…”

Section: Introductionmentioning

confidence: 99%

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Operando Surface Spectroscopy and Microscopy during Catalytic Reactions: From Clusters via Nanoparticles to Meso‐Scale Aggregates

Rupprechter

2021

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described as metal dispersion (number of metal surface atoms relative to the total number of metal atoms in the catalyst), whereas the support is characterized by the specific surface area (m 2 g −1). For hemispherical metal particles of ≈1.5, 2, 5, and 10 nm diameter, the dispersion is about 0.8, 0.6, 0.3, and 0.1, respectively, illustrating why the nanoscale is required not to waste precious metal inside the particles. The ultimate dispersion is, of course, provided by single metal atoms and this concept is followed in "single atom catalysis" or "single site catalysis". [10-17] However, the adsorption and reaction steps of a catalytic reaction do typically not occur on isolated single atoms, but also involve neighboring sites, for example, of the oxide support [18] or of a metal matrix (for bimetallic nanoparticles, active metal atoms may be embedded in an inert or less-active metal matrix [11,19-23]). The so-called site isolation of active atoms may prevent CC bond cleavage (coking), which requires at least two neighboring active metals. In any case, the stability of the single atoms is the key challenge, as atoms may diffuse and sinter. Furthermore, for example, Pt, Pd, Cu, or Au atoms are mobilized by CO, [24-28] forming CO-M 1 units that may eventually sinter into larger clusters. Herein, we define metal clusters as entities with less than ≈100 atoms, characterizing the so-called "non-scalable" regime (Figure 1a). [29] Their atomic and electronic structure is significantly different from that of bulk metals, for example, with respect to atom positions (icosahedral vs face centered cubic fcc), distances (lattice contraction or expansion), and band structure (semiconductor vs metal). Clearly, these properties are size-dependent ("each atom counts" [30,31]), with pronounced impact on adsorption and reaction properties. [5,32] Accordingly, nanoparticles with more than ≈100 atoms are in the "scalableregime" and start to have or exhibit bulk atomic and electronic structure. [6,32-34] Nevertheless, the relative contributions of corner, edge, step, terrace and phase boundary sites on the surface of a nanoparticle (Figure 1b,c) are still size-dependent. [35,36] Meso-scale ("black") powders of metals are clearly bulk-like and have very low dispersion (Figure 1d), but the µm-sized aggregates still consist of adjoining nanocrystals with structured surfaces, comparable to that of true nanoparticles. Operando characterization of working catalysts, requiring per definitionem the simultaneous measurement of catalytic performance, is crucial to identify the relevant catalyst structure, composition and adsorbed species. Frequently applied operando techniques are discussed, including X-ray absorption spectroscopy, near ambient pressure X-ray photoelectron spectroscopy and infrared spectroscopy. In contrast to these area-averaging spectroscopies, operando surface microscopy by photoemission electron microscopy delivers spatially-resolved data, directly visualizing catalyst heterogeneity. For thorough interpretation, the exper...

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Operando Surface Spectroscopy and Microscopy during Catalytic Reactions: From Clusters via Nanoparticles to Meso‐Scale Aggregates

Rupprechter

2021

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“…However, the binding energy peaks of both Co and Gd shifts toward a little positive value concerning freshly prepared Gd‐CoB that may be due to the surface oxidation, most likely occur when we exposed metal‐based catalysts in alkaline medium at high anodic potential (Figure 4). [ 42 ] The peak intensity ratio for Co o /Co +2 also decreased from 3.41 to 2.9. The O 1s peak showed a transition from a surface dominated by an adsorbed water molecule with an increase in the intensity of O ads (Figure S17, Supporting Information).…”

Section: Electrochemical Activitymentioning

confidence: 99%

Gold‐Supported Gadolinium Doped CoB Amorphous Sheet: A New Benchmark Electrocatalyst for Water Oxidation with High Turnover Frequency

Haq

Mansour

Munir

et al. 2020

Adv Funct Materials

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Electrochemical water splitting has been considered a promising approach for green and sustainable hydrogen as a future energy carrier. However, the lack of high performance and inexpensive electrocatalysts for kinetically sluggish oxygen evolution reaction (OER) hinder the practical application. Here, the noteworthy enhancement of electrodeposited cobalt boride (CoB) nanosheets from the combined effect of using gadolinium as a dopant and thin film of gold as prudent support is demonstrated. The free-standing Gd-CoB@Au exhibits remarkable electrochemical performance, high intrinsic activity, and lower reaction resistance, which are confirmed by lower onset potential, small charge transfer resistance, lower Tafel slope value, and high turnover frequency. Furthermore, the post-OER characterization signpost, no observable change in the chemical structure or morphology of nanosheets during the long-lasting oxidation process. Because of the inexpensive, facile, and scalable one-step preparation processes, the catalyst is highly encouraging for large-scale practical applications.in pursuing toward viable electrochemical water splitting module. [1] The HER follows a relatively simple mechanism and various cost-effective and efficient metal/ alloy-based catalysts have been developed to produce hydrogen at fairly low overpotential. [2] A serious challenge, however, is the slow rate of multistep OER, which requires high activation energy and thus large overpotential to break OH bond, and to form an OO bond and transfer 04 electrons essentially required for oxygen evolution from two water molecules at the same time. [3] The slow rate of OER in turn adversely affects the overall rate of water splitting for hydrogen production. [4] It is, therefore, essentially required to develop stable, economical, and effective electrocatalysts for OER for the feasible production of H 2 by water splitting. Currently, IrO 2 and RuO 2 are the benchmark OER catalysts to significantly improve slow kinetics of oxygen evolution at the anode. These electrocatalysts are made up of expensive precious metals, and their supply is not sustainable and is, therefore, not much suitable for large-scale applications in water oxidation systems. [5] Besides precious metals, several costeffective nanoscale materials including layer double hydroxides, perovskite, amorphous/crystalline metal hydroxides have been extensively explored for OER. [6][7][8] Hence, it is well established, that nano-structuring is one of the widely adopted strategies to enhance the catalytic properties and selectivity, toward the OER for practical application. [9] However, low mass loading of catalyst, mechanical and chemical instability, less exposed surface area, reproducibility, potentially induced phase/electronic transformation during catalysis, surface leaching of the catalyst due to the low adhesion of catalyst are still serious concerns that need to be addressed. [10] Also, the use of powder nanomaterials traditionally needs various binders (Nafion/polymers) for the fabricati...

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“…Cobalt oxide has great potential for catalysis [12,14,15], electrochemistry [16,17], sensing devices [18] and magnetic materials [19] to name a few. There are several cobalt oxides that showed significant performance to their potential, namely CoO, CoO2, Co2O3, CoO(OH) and Co3O4.…”

Section: Pengaruh Suhu Kalsinasi Pada Cobalt Oksida Dan Kinerjanya Untukmentioning

confidence: 99%

The Effect of Calcination Temperature on Cobalt Oxide Species and Performance for Catalytic Ozonation of NH4+ in Water

Mahardiani

2019

JKPK

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Cobalt oxide catalysts can be prepared by impregnation and calcined under different temperature to obtained different species of cobalt oxide, namely CoO(OH), Co3O4, and CoO. Co3O4 was the most appropriate catalyst for decomposing NH4+ with O3 in the presence of Cl– because of relatively high activity, 74%, and high selectivity for gas products, 88%, compared to CoO and CoO(OH). Cl– is necessary to proceed the catalytic ozonation of NH4+ since Cl– participate in the catalytic ozonation mechanism, while SO42– inhibited the process. During the catalytic ozonation of NH4+, Co3O4 showed no deactivation rather than enhanced the catalytic performance after repeated used up to 100% of NH4+ conversion. The Co3O4 can be regenerated by recalcining the catalyst under air at high temperature.

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Operando Surface X-ray Diffraction Studies of Structurally Defined Co₃O₄ and CoOOH Thin Films during Oxygen Evolution

Cited by 112 publications

References 60 publications

Operando Surface Spectroscopy and Microscopy during Catalytic Reactions: From Clusters via Nanoparticles to Meso‐Scale Aggregates

Operando Surface Spectroscopy and Microscopy during Catalytic Reactions: From Clusters via Nanoparticles to Meso‐Scale Aggregates

Gold‐Supported Gadolinium Doped CoB Amorphous Sheet: A New Benchmark Electrocatalyst for Water Oxidation with High Turnover Frequency

The Effect of Calcination Temperature on Cobalt Oxide Species and Performance for Catalytic Ozonation of NH4+ in Water

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