Wavelet analysis of extended X-ray absorption fine structure data: Theory, application

Xia, Zhaoming; Zhang, Hao; Shen, Kongchao; Qu, Yongquan; Jiang, Zheng

doi:10.1016/j.physb.2018.04.039

Cited by 144 publications

(89 citation statements)

References 34 publications

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“…In the wavelet transform spectrum, the horizontal axis shows the wave vector number k , which is the key to distinguish different kinds of coordination atoms. [ 23 ] As shown in Figure 1d–f, the coordination features of Mo in PS‐MoNi are similar to those in Mo metal, with an intensity maximum at ≈2.4 Å and in the high‐ k part assigned to MoMo coordination. For MoO 2 , the high‐intensity region was observed at ≈1.5 Å and in the low‐ k part assigned to MoO coordination.…”

Section: Figurementioning

confidence: 67%

Phase‐Separated Mo–Ni Alloy for Hydrogen Oxidation and Evolution Reactions with High Activity and Enhanced Stability

Song¹,

Jin²,

Zhang

et al. 2021

Advanced Energy Materials

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The development of alkaline polymer electrolyte fuel cells and alkaline water electrolysis requires nonprecious metal catalysts for the hydrogen oxidation reaction (HOR) and hydrogen evolution reaction (HER). Herein, it is reported a phase‐separated Mo–Ni alloy (PS‐MoNi) that is composed of Mo metal and embedded Ni metal nanoparticles. The PS‐MoNi shows excellent hydrogen electrode activity with a high exchange current density (−4.883 mA cm−2), which is comparable to the reported highest value for non‐noble catalysts. Moreover, the amorphous phase‐separated Mo–Ni alloy has better structural and electrochemical stability than the intermetallic compound Mo–Ni alloy (IC‐MoNi). The breakdown potential of PS‐MoNi is as high as 0.32 V, which is much higher than that of reported IC‐MoNi. The X‐ray absorption near edge structure (XANES) and density functional theory (DFT) calculations indicate the electrons transfer from Mo to Ni for PS‐MoNi, leading to suitable adsorption free energies of H* (ΔGH*) on the surface of Mo. This means that the electron density modulation of Mo metal by embedded Ni metal nanoparticles can produce excellent HOR and HER performance.

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Section: Figurementioning

confidence: 67%

Phase‐Separated Mo–Ni Alloy for Hydrogen Oxidation and Evolution Reactions with High Activity and Enhanced Stability

Song¹,

Jin²,

Zhang

et al. 2021

Advanced Energy Materials

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show abstract

“…Moreover, EXAFS wavelet transform (WT), a powerful tool for discerning the contribution of each pathway in both R-space and k-space, was performed to discriminate the backscattering atoms (Fig. 2d) 36 . As compared to Ni foil and Ni(OH) 2 , the observation of a single obvious maximum at ~4 Å −1 for Ni-N-C provided unequivocal support for the absence of a Ni-Ni scattering path.…”

Section: Resultsmentioning

confidence: 99%

Dynamic Structural Changes in Nickel Single-Atom Catalysts During Electrochemical Reduction of CO2 to CO

Mei

et al. 2021

Preprint

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Electrochemical CO2 reduction reaction (ECO2RR) is an important route for global carbon abatement. However, a comprehensive picture of the structure evolution of metal active sites is currently lacked in ECO2RR. Here, we present the first full view of Ni single-atom catalyst for ECO2RR over a broad potential range. Comprehensive X-ray absorption spectroscopy (XAS) analyses confirmed the Ni coordinated with pyrrole nitrogen in the form of Ni-N4 attached with an axial O2 ligand. Operando XAS revealed the precise structure of the Ni single-atom catalyst that dynamically changes with the shift of applied potentials. Such changes ultimately contributed to the CO selectivity variation ranging from 20%-99%. Interestingly, the Ni center was found to move toward the N4 plane during the ECO2RR, which played a crucial role of reaching near-unity CO selectivity. Together with theoretical calculations, a clear quantitative correlation between the dynamic configuration and the catalytic properties was established.

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“…To further determine the configurations of Rh 0 -Rh 3+ sites in RBVOM-H, theoretical calculation of XANES with the FDMNES code [18] and wavelet transform (WT) of k 2 -weighted c(k) signals based on Morlet wavelets [19] were carried out.…”

Section: Local Structure Investigation Of Anchored Rh Speciesmentioning

confidence: 99%

Boosting Photocatalytic Water Oxidation Over Bifunctional Rh⁰‐Rh³⁺ Sites

et al. 2021

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Photocatalytic water splitting provides an economically feasible way for converting solar energy into hydrogen. Great efforts have been devoted to developing efficient photocatalysts;however,the surface catalytic reactions,especially for the sluggish oxygen evolution reaction (OER), still remain ac hallenge,w hich limits the overall photocatalytic energy efficiency.Herein, we design aRh n cluster cocatalyst, with Rh 0 -Rh 3+ sites anchoring the Mo-doped BiVO 4 model photocatalytic system. The resultant photocatalyst enables ahigh visiblelight photocatalytic oxygen production activity of 7.11 mmol g À1 h À1 and an apparent quantum efficiency of 29.37 %a t4 20 nm. The turnover frequency (TOF) achieves 416.73 h À1 ,w hich is 378 times higher than that of the photocatalyst only with Rh 3+ species.O perando X-ray absorption characterization shows the OER process on the Rh 0 -Rh 3+ sites. The DFT calculations further illustrate ab ifunctional OER mechanism over the Rh 0 -Rh 3+ sites,i nw hicht he oxygen intermediate attacks the Rh 3+ sites with assistance of ahydrogen atom transfer to the Rh 0 sites,t hus breaking the scaling relationship of various oxygen intermediates.

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Wavelet analysis of extended X-ray absorption fine structure data: Theory, application

Cited by 144 publications

References 34 publications

Phase‐Separated Mo–Ni Alloy for Hydrogen Oxidation and Evolution Reactions with High Activity and Enhanced Stability

Phase‐Separated Mo–Ni Alloy for Hydrogen Oxidation and Evolution Reactions with High Activity and Enhanced Stability

Dynamic Structural Changes in Nickel Single-Atom Catalysts During Electrochemical Reduction of CO2 to CO

Boosting Photocatalytic Water Oxidation Over Bifunctional Rh⁰‐Rh³⁺ Sites

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Wavelet analysis of extended X-ray absorption fine structure data: Theory, application

Cited by 144 publications

References 34 publications

Phase‐Separated Mo–Ni Alloy for Hydrogen Oxidation and Evolution Reactions with High Activity and Enhanced Stability

Phase‐Separated Mo–Ni Alloy for Hydrogen Oxidation and Evolution Reactions with High Activity and Enhanced Stability

Dynamic Structural Changes in Nickel Single-Atom Catalysts During Electrochemical Reduction of CO2 to CO

Boosting Photocatalytic Water Oxidation Over Bifunctional Rh0‐Rh3+ Sites

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Boosting Photocatalytic Water Oxidation Over Bifunctional Rh⁰‐Rh³⁺ Sites