In Situ X-ray Absorption Spectroscopy Studies of Nanoscale Electrocatalysts

Wang, Maoyu; Árnadóttir, Líney; Xu, Zhichuan J.; Feng, Zhenxing

doi:10.1007/s40820-019-0277-x

Cited by 231 publications

(220 citation statements)

References 97 publications

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“…XPS reveals higher binding energy for the Ti 2p electrons of a‐TiO 2 ‐BDC compared to those of MIL‐125‐Ti (Figure 1e), in line with higher‐energy K‐edge absorption of a‐TiO 2 ‐BDC recorded by X‐ray absorption near edge structure (XANES) measurements (Figure 1f). These results further corroborate that the acid treatment destroys the Ti‐ligand coordination in the MOF structure and converts it to TiO 2 ‐like species.…”

Section: Resultssupporting

confidence: 73%

Metal Organic Framework Derivative Improving Lithium Metal Anode Cycling

Zhong

Lin

Wang

et al. 2020

Adv Funct Materials

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This work demonstrates a new approach in using metal organic framework (MOF) materials to improve Li metal batteries, a burgeoning rechargeable battery technology. Instead of using the MIL‐125‐Ti MOF structure directly, the material is decomposed into intimately‐mixed amorphous titanium dioxide and crystalline terephthalic acid. The resulting composite material outperforms the oxide alone, the organic component alone, and the parent MOF in suppressing Li dendrite growth and extending cycle life of Li metal electrodes. Coated on a commercial polypropylene separator, this material induces the formation of a desirable solid electrolyte interphase layer comprising mechanically flexible organic species and ionically conductive lithium nitride species, which in turn leads to Li||Cu and Li||Li cells that can stably operate for hundreds of charging–discharging cycles. In addition, this material strongly adsorbs lithium polysulfides and can also benefit the cathode of lithium–sulfur batteries.

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Section: Resultssupporting

confidence: 73%

Metal Organic Framework Derivative Improving Lithium Metal Anode Cycling

Zhong

Lin

Wang

et al. 2020

Adv Funct Materials

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“…As the temperature is increased to 400 °C, the oxidation state of Fe was reduced, which could be caused by the formation of Fe−N bonding. Although it is hard for EXAFS to distinguish Fe‐N and Fe‐O scattering unambiguously The EXAFS data (Supporting Information, Figure S10) at high k (>8 Å −1 ) becomes noisy, further increasing the ambiguity of EXAFS to distinguish the Fe‐O and Fe‐N. However, according to our previous analysis by using Mössbauer spectroscopy, Fe‐N coordination is more likely.…”

Section: Resultsmentioning

confidence: 93%

“…This indicates that nearly all the FeO x decomposed into atomically dispersed Fe sites, which is observed by MAADF‐STEM imaging as well. The ZIF‐NC‐0.5Fe‐700 sample, after thermal activation at 700 °C, showed an increased pre‐edge intensity (inset of Figure a) that is a sign of lower symmetry around Fe atoms or shorter Fe−N bond length in Fe‐N 4 configurations . The Fe‐N coordination number is around 4 at and above temperatures of 400 °C, implying a mild thermal activation is able to facilitate the formation of FeN 4 sites.…”

Section: Resultsmentioning

confidence: 98%

Thermally Driven Structure and Performance Evolution of Atomically Dispersed FeN₄ Sites for Oxygen Reduction

et al. 2019

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FeN4 moieties embedded in partially graphitized carbon are the most efficient platinum group metal free active sites for the oxygen reduction reaction in acidic proton‐exchange membrane fuel cells. However, their formation mechanisms have remained elusive for decades because the Fe−N bond formation process always convolutes with uncontrolled carbonization and nitrogen doping during high‐temperature treatment. Here, we elucidate the FeN4 site formation mechanisms through hosting Fe ions into a nitrogen‐doped carbon followed by a controlled thermal activation. Among the studied hosts, the ZIF‐8‐derived nitrogen‐doped carbon is an ideal model with well‐defined nitrogen doping and porosity. This approach is able to deconvolute Fe−N bond formation from complex carbonization and nitrogen doping, which correlates Fe−N bond properties with the activity and stability of FeN4 sites as a function of the thermal activation temperature.

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“…The former can provide the detailed information about the electronic structure and chemical state of target atoms, while the latter can provide the precise local structural information of target atoms such as coordination number and chemical bond length. XAS in the hard X‐ray region can be done under ambient conditions and is suitable for in situ measurements to track the catalyst evolution and surface adsorption during electrochemical reactions . Our group recently used in situ XAS at the Bi L‐edge to study the CO 2 RR to formate on highly defective Bi 2 O 3 nanotubes (Figure g–i) .…”

Section: Mechanistic Studies Using In Situ Characterization Techniquesmentioning

confidence: 99%

Promises of Main Group Metal–Based Nanostructured Materials for Electrochemical CO₂ Reduction to Formate

Han

Pan

et al. 2019

Advanced Energy Materials

498

384

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Selective CO2 reduction to formic acid or formate is the most technologically and economically viable approach to realize electrochemical CO2 valorization. Main group metal–based (Sn, Bi, In, Pb, and Sb) nanostructured materials hold great promise, but are still confronted with several challenges. Here, the current status, challenges, and future opportunities of main group metal–based nanostructured materials for electrochemical CO2 reduction to formate are reviewed. Firstly, the fundamentals of electrochemical CO2 reduction are presented, including the technoeconomic viability of different products, possible reaction pathways, standard experimental procedure, and performance figures of merit. This is then followed by detailed discussions about different types of main group metal–based electrocatalyst materials, with an emphasis on underlying material design principles for promoting the reaction activity, selectivity, and stability. Subsequently, recent efforts on flow cells and membrane electrode assembly cells are reviewed so as to promote the current density as well as mechanistic studies using in situ characterization techniques. To conclude a short perspective is offered about the future opportunities and directions of this exciting field.

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In Situ X-ray Absorption Spectroscopy Studies of Nanoscale Electrocatalysts

Cited by 231 publications

References 97 publications

Metal Organic Framework Derivative Improving Lithium Metal Anode Cycling

Metal Organic Framework Derivative Improving Lithium Metal Anode Cycling

Thermally Driven Structure and Performance Evolution of Atomically Dispersed FeN₄ Sites for Oxygen Reduction

Promises of Main Group Metal–Based Nanostructured Materials for Electrochemical CO₂ Reduction to Formate

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In Situ X-ray Absorption Spectroscopy Studies of Nanoscale Electrocatalysts

Cited by 231 publications

References 97 publications

Metal Organic Framework Derivative Improving Lithium Metal Anode Cycling

Metal Organic Framework Derivative Improving Lithium Metal Anode Cycling

Thermally Driven Structure and Performance Evolution of Atomically Dispersed FeN4 Sites for Oxygen Reduction

Promises of Main Group Metal–Based Nanostructured Materials for Electrochemical CO2 Reduction to Formate

Contact Info

Product

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About

Thermally Driven Structure and Performance Evolution of Atomically Dispersed FeN₄ Sites for Oxygen Reduction

Promises of Main Group Metal–Based Nanostructured Materials for Electrochemical CO₂ Reduction to Formate