Phase segregation reversibility in mixed-metal hydroxide water oxidation catalysts

Kuai, Chunguang; Xu, Zhengrui; Xi, Cong; Hu, Anyang; Yang, Zhijie; Zhang, Yan; Sun, Chengjun; Li, Luxi; Sokaras, Dimosthenis; Dong, Cunku; Qiao, Shi Zhang; Du, Xi‐Wen; Lin, Feng

doi:10.1038/s41929-020-0496-z

Cited by 251 publications

(244 citation statements)

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“…While the blueshifts of Co-O peak from 1.62 Å to 1.44 Å and the redshifts of Co-M (Co, Ni, or Fe) peak from 2.27 Å to 2.40 Å after OER process confirm the increase of Co oxidation state via the unavoidable surface oxidation. [19,40] Similarly, Ni K-edge XANES spectra show the slight shift to higher energy after 24 h OER test, which indicates the change in Ni coordination (Figure 6e,h; Figure S70, Supporting Information). The Fe K-edge XANES spectra of initial and post-OER cMOF/LDH-48 show almost overlapping response signals around the near-edge (Figure 6f,i; Figure S71, Supporting Information), indicating that the chemical structure of Fe is preserved during 24 h OER test.…”

Section: The Conjugation Of Metal-organic Framework (Mofs) Into Diffmentioning

confidence: 99%

Lattice Matching Growth of Conductive Hierarchical Porous MOF/LDH Heteronanotube Arrays for Highly Efficient Water Oxidation

et al. 2021

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The conjugation of metal–organic frameworks (MOFs) into different multicomponent materials to precisely construct aligned heterostructures is fascinating but elusive owing to the disparate interfacial energy and nucleation kinetics. Herein, a promising lattice‐matching growth strategy is demonstrated for conductive MOF/layered double hydroxide (cMOF/LDH) heteronanotube arrays with highly ordered hierarchical porous structures enabling an ultraefficient oxygen evolution reaction (OER). CoNiFe‐LDH nanowires are used as interior template to engineer an interface by inlaying cMOF and matching two crystal lattice systems, thus conducting a graft growth of cMOF/LDH heterostructures along the LDH nanowire. A class of hierarchical porous cMOF/LDH heteronanotube arrays is produced through continuously regulating the transformation degree. The synergistic effects of the cMOF and LDH components significantly promote the chemical and electronic structures of the heteronanotube arrays and their electroactive surface area. Optimized heteronanotube arrays exhibit extraordinary OER activity with ultralow overpotentials of 216 and 227 mV to deliver current densities of 50 and 100 mA cm−2 with a small Tafel slope of 34.1 mV dec−1, ranking it among the best MOF and non‐noble‐metal‐based catalysts for OER. The robust performance under high current density and vigorous gas bubble conditions enable such hierarchical MOF/LDH heteronanotube arrays as promising materials for practical water electrolysis.

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Section: The Conjugation Of Metal-organic Framework (Mofs) Into Diffmentioning

confidence: 99%

Lattice Matching Growth of Conductive Hierarchical Porous MOF/LDH Heteronanotube Arrays for Highly Efficient Water Oxidation

et al. 2021

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“…The wavelet transform (WT) analyses of the Cu K-edge EXAFS spectra were carried out to visually identify the local coordination of Cu. The WT technique, which can differentiate the contribution of different scattering paths by decomposing the R and k signals of the EXAFS, is a powerful tool for distinguishing atoms neighboring a metal center ( Funke et al., 2005 ; Stevens et al., 2017 ; Kuai et al., 2020 ). As seen in WT EXAFS profiles of 3CuO@sil-1 and 23CuO/SiO 2 ( Figures 3 C and 3D), one central maximum at R ≈ 1.2–1.5 Å and k ≈ 4 Å −1 is identified as the first shell Cu−O coordination.…”

Section: Resultsmentioning

confidence: 99%

Encapsulation of CuO nanoparticles within silicalite-1 as a regenerative catalyst for transfer hydrogenation of furfural

et al. 2021

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Summary Catalytic transfer hydrogenation (CTH) of biomass-derived furfural (FAL) to furfuryl alcohol is recognized as one of the most versatile techniques for biomass valorization. However, the irreversible sintering of metal sites under the high-temperature reaction or during the coke removal regeneration process poses a serious concern. Herein, we present a silicalite-1-confined ultrasmall CuO structure (CuO@silicalite-1) and then compared its catalytic efficiency against conventional surface-supported CuO structure (CuO/silicalite-1) toward CTF of FAL with alcohols. Characterization results revealed that CuO nanoparticles encapsulated within the silicalite-1 matrix are ∼1.3 nm in size in CuO@silicalite-1, exhibiting better dispersion as compared to that in the CuO/silicalite-1. The CuO@silicalite-1, as a result, exhibited nearly 100-fold higher Cu-mass-based activity than the CuO/silicalite-1 counterpart. More importantly, the activity of the CuO@silicalite-1 catalyst can be regenerated via facile calcination to remove the surface-bound carbon deposits, unlike the CuO/silicalite-1 that suffered severe deactivation after use and cannot be effectively regenerated.

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“…However, the high price and low reserve of noble metals limit their practical utilization. Recently, nickel-iron layered double hydroxide (NiFe-LDH) has attracted much attention as an active OER catalyst in alkaline solution, [6][7][8][9][10] whereas its activity for alkaline HER is rather low due to weak hydrogen adsorption (H ad ), leading to poor performance of overall water splitting. [11][12] Therefore, it is of great importance to enhance the HER activity of NiFe LDH, especially at large current density (>1000 mA cm −2 ) for industrial application.…”

Section: Introductionmentioning

confidence: 99%

Valence‐State Effect of Iridium Dopant in NiFe(OH)₂ Catalyst for Hydrogen Evolution Reaction

Wang

et al. 2021

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Engineering high‐performance electrocatalysts is of great importance for energy conversion and storage. As an efficient strategy, element doping has long been adopted to improve catalytic activity, however, it has not been clarified how the valence state of dopant affects the catalytic mechanism and properties. Herein, it is reported that the valence state of a doping element plays a crucial role in improving catalytic performance. Specifically, in the case of iridium doped nickel‐iron layer double hydroxide (NiFe‐LDH), trivalent iridium ions (Ir3+) can boost hydrogen evolution reaction (HER) more efficiently than tetravalent iridium (Ir4+) ions. Ir3+‐doped NiFe‐LDH delivers an ultralow overpotential (19 mV @ 10 mA cm−2) for HER, which is superior to Ir4+ doped NiFe‐LDH (44 mV@10 mA cm−2) and even commercial Pt/C catalyst (40 mV@ 10 mA cm−2), and reaches the highest level ever reported for NiFe‐LDH‐based catalysts. Theoretical and experimental analyses reveal that Ir3+ ions donate more electrons to their neighboring O atoms than Ir4+ ions, which facilitates the water dissociation and hydrogen desorption, eventually boosting HER. The same valence‐state effect is found for Ru and Pt dopants in NiFe‐LDH, implying that chemical valence state should be considered as a common factor in modulating catalytic performance.

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Phase segregation reversibility in mixed-metal hydroxide water oxidation catalysts

Cited by 251 publications

References 61 publications

Lattice Matching Growth of Conductive Hierarchical Porous MOF/LDH Heteronanotube Arrays for Highly Efficient Water Oxidation

Lattice Matching Growth of Conductive Hierarchical Porous MOF/LDH Heteronanotube Arrays for Highly Efficient Water Oxidation

Encapsulation of CuO nanoparticles within silicalite-1 as a regenerative catalyst for transfer hydrogenation of furfural

Valence‐State Effect of Iridium Dopant in NiFe(OH)₂ Catalyst for Hydrogen Evolution Reaction

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Phase segregation reversibility in mixed-metal hydroxide water oxidation catalysts

Cited by 251 publications

References 61 publications

Lattice Matching Growth of Conductive Hierarchical Porous MOF/LDH Heteronanotube Arrays for Highly Efficient Water Oxidation

Lattice Matching Growth of Conductive Hierarchical Porous MOF/LDH Heteronanotube Arrays for Highly Efficient Water Oxidation

Encapsulation of CuO nanoparticles within silicalite-1 as a regenerative catalyst for transfer hydrogenation of furfural

Valence‐State Effect of Iridium Dopant in NiFe(OH)2 Catalyst for Hydrogen Evolution Reaction

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Valence‐State Effect of Iridium Dopant in NiFe(OH)₂ Catalyst for Hydrogen Evolution Reaction