scholarly journals Mechanisms of Hydrogen Evolution Reaction in Two-Dimensional Nitride MXenes Using In Situ X-Ray Absorption Spectroelectrochemistry

ACS Catalysis ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 3128-3136
Author(s):  
Abdoulaye Djire ◽  
Hanyu Zhang ◽  
Benjamin J. Reinhart ◽  
O. Charles Nwamba ◽  
Nathan R. Neale
Keyword(s):  
Hydrogen Evolution ◽  
Hydrogen Evolution Reaction ◽  
Two Dimensional ◽  
X Ray ◽  
X Ray Absorption

Synthesis and performance optimization of ultrathin two-dimensional CoFePt alloy materials via in situ topotactic conversion for the hydrogen evolution reaction

2019 ◽  
Vol 7 (16) ◽  
pp. 9517-9522 ◽  
Author(s):  
Qian Zhang ◽  
Yun Kuang ◽  
Yaping Li ◽  
Ming Jiang ◽  
Zhao Cai ◽  
...  
Keyword(s):  
Hydrogen Evolution ◽  
Hydrogen Evolution Reaction ◽  
Performance Optimization ◽  
Alkaline Solutions ◽  
Two Dimensional ◽  
Nanosheet Arrays ◽  
And Performance

Two-dimensional CoFe–Pt1% nanosheet arrays fabricated via topotactic conversion for the hydrogen evolution reaction in alkaline solutions.

scholarly journals In Situ Wet Etching of MoS2@dWO3 Heterostructure as Ultra-Stable Highly Active Electrocatalyst for Hydrogen Evolution Reaction

Catalysts ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 977
Author(s):  
Xintian Liu ◽  
Congwei Wang
Keyword(s):  
Hydrogen Evolution ◽  
Hydrogen Evolution Reaction ◽  
Oxygen Vacancies ◽  
Rapid Development ◽  
Strong Stability ◽  
Wet Etching ◽  
Two Dimensional ◽  
Highly Active ◽  
Anisotropic Substrate

Electrocatalysts featuring robust structure, excellent catalytic activity and strong stability are highly desirable, but challenging. The rapid development of two-dimensional transition metal chalcogenide (such as WO3, MoS2 and WS2) nanostructures offers a hopeful strategy to increase the active edge sites and expedite the efficiency of electronic transport for hydrogen evolution reaction. Herein, we report a distinctive strategy to construct two-dimensional MoS2@dWO3 heterostructure nanosheets by in situ wet etching. Synthesized oxygen-incorporated MoS2-was loaded on the surface of defective WO3 square nanoframes with abundant oxygen vacancies. The resulting nanocomposite exhibits a low overpotential of 191 mV at 10 mA cm−2 and a very low Tafel slope of 42 mV dec−1 toward hydrogen evolution reaction. The long-term cyclic voltammetry cycling of 5000 cycles and more than 80,000 s chronoamperometry tests promises its outstanding stability. The intimate and large interfacial contact between MoS2 and WO3, favoring the charge transfer and electron–hole separation by the synergy of defective WO3 and oxygen-incorporated MoS2, is believed the decisive factor for improving the electrocatalytic efficiency of the nanocomposite. Moreover, the defective WO3 nanoframes with plentiful oxygen vacancies could serve as an anisotropic substrate to promote charge transport and oxygen incorporation into the interface of MoS2. This work provides a unique methodology for designing and constructing excellently heterostructure electrocatalysts for hydrogen evolution reaction.

scholarly journals Elucidating the formation and structural evolution of platinum single-site catalysts for hydrogen evolution reaction

2021 ◽  
Author(s):  
Peng Tang ◽  
Hyeon Jeong Lee ◽  
Kevin Hurlbutt ◽  
Po-Yuan Huang ◽  
Sudarshan Narayanan ◽  
...  
Keyword(s):  
Hydrogen Evolution ◽  
Hydrogen Evolution Reaction ◽  
Clean Energy ◽  
Single Site ◽  
Ex Situ ◽  
Edge Structure ◽  
X Ray ◽  
Production Of Hydrogen ◽  
Single Site Catalysts ◽  
X Ray Absorption

Platinum single-site catalysts (SSCs) are a promising technology for the production of hydrogen from clean energy sources. They have high activity and maximal platinum-atom utilisation. However, the bonding environment of platinum during operation is poorly understood. In this work, we use operando, synchrotron-X-ray absorption spectroscopy to study the platinum bonding in SSCs. First, we synthesise an atomically dispersed platinum complex with aniline and chloride ligands onto graphene and characterise it with ex-situ electron microscopy, X-ray diffractometry, X-ray photoelectron spectroscopy, X-ray absorption near edge structure spectroscopy (XANES), and extended X-ray absorption fine structure spectroscopy (EXAFS). Then, by operando EXAFS and XANES, we show that as a negatively biased potential is applied, the Pt-N bonds break first followed by the Pt-Cl bonds. The platinum is reduced from platinum(II) to metallic platinum(0) by the onset of the hydrogen-evolution reaction at 0 V. Furthermore, we observe an increase in Pt-Pt bonding, indicating the formation of platinum agglomerates. Together, these results indicate that while aniline is used to prepare platinum SSCs, the single-site complexes are decomposed and platinum agglomerates at operating potentials. This work is an important contribution to the understanding of the bonding environment and the evolution of the molecular structure of platinum complexes in SSCs.

In situ X-ray diffraction and X-ray absorption spectroscopy of electrocatalysts for energy conversion reactions

2020 ◽  
Vol 8 (37) ◽  
pp. 19079-19112 ◽  
Author(s):  
Chia-Jui Chang ◽  
Yanping Zhu ◽  
Jiali Wang ◽  
Hsiao-Chien Chen ◽  
Ching-Wei Tung ◽  
...  
Keyword(s):  
Absorption Spectroscopy ◽  
Hydrogen Evolution Reaction ◽  
Oxygen Evolution Reaction ◽  
Recent Progress ◽  
Reduction Reaction ◽  
X Ray Diffraction ◽  
X Ray ◽  
X Ray Absorption ◽  
Made In

This review summarizes the recent progress made in electrocatalysts with regard to oxygen evolution reaction, hydrogen evolution reaction, and CO2 reduction reaction by means of in situ X-ray diffraction and X-ray absorption spectroscopy.

scholarly journals In Situ Study of Graphene Oxide Quantum Dot-MoSx Nanohybrids as Hydrogen Evolution Catalysts

Surfaces ◽  
2020 ◽  
Vol 3 (2) ◽  
pp. 225-236
Author(s):  
Marco Favaro ◽  
Mattia Cattelan ◽  
Stephen W. T. Price ◽  
Andrea E. Russell ◽  
Laura Calvillo ◽  
...  
Keyword(s):  
Hydrogen Evolution ◽  
Electrochemical Techniques ◽  
Graphene Quantum Dots ◽  
Operating Conditions ◽  
X Ray Diffraction ◽  
Hydrogen Atoms ◽  
X Ray ◽  
X Ray Absorption

Graphene quantum dots (GOQDs)-MoSx nanohybrids with different MoSx stoichiometries (x = 2 and 3) were prepared in order to investigate their chemical stability under hydrogen evolution reaction (HER) conditions. Combined photoemission/electrochemical (XPS/EC) measurements and operando X-ray absorption spectroscopy (XAS) were employed to determine the chemical changes induced on the MoSx-based materials as a function of the applied potential. This in situ characterization indicates that both MoS2 and MoS3 materials are stable under operating conditions, although sulfur terminal sites in the MoS3 nanoparticles are converted from S-dimer (S22−) to S-monomer (S2−), which constitute the first sites where the hydrogen atoms are adsorbed for their subsequent evolution. In order to complete the characterization of the GOQDs-MoSx nanohybrids, the composition and particle size were determined by X-ray photoemission spectroscopy (XPS), X-ray diffraction (XRD) and Raman spectroscopy; whereas the HER activity was studied by conventional electrochemical techniques.

In Situ X-Ray Absorption Studies of the Electrochemical Reduction of Hydroxocobalamin

1997 ◽  
Vol 7 (C2) ◽  
pp. C2-619-C2-620 ◽  
Author(s):  
M. Giorgett ◽  
I. Ascone ◽  
M. Berrettoni ◽  
S. Zamponi ◽  
R. Marassi
Keyword(s):  
Electrochemical Reduction ◽  
X Ray ◽  
Absorption Studies ◽  
X Ray Absorption

Application of In Situ X-ray Absorption Spectroscopy to Study Dilute Chromium Ions in a Molten Chloride Salt

2019 ◽  
Author(s):  
Jisue Moon ◽  
Carter Abney ◽  
Dmitriy Dolzhnikov ◽  
James M. Kurley ◽  
Kevin A. Beyer ◽  
...  
Keyword(s):  
Absorption Spectroscopy ◽  
Local Structure ◽  
Chloride Salt ◽  
X Ray ◽  
Molten Chloride ◽  
Stable Species ◽  
Higher Temperature ◽  
Cr Concentration ◽  
X Ray Absorption

The local structure of dilute CrCl<sub>3</sub> in a molten MgCl<sub>2</sub>:KCl salt was investigated by <i>in situ</i> x-ray absorption spectroscopy (XAS) at temperatures from room temperature to 800<sup>o</sup>C. This constitutes the first experiment where dilute Cr speciation is explored in a molten chloride salt, ostensibly due to the compounding challenges arising from a low Cr concentration in a matrix of heavy absorbers at extreme temperatures. CrCl<sub>3</sub> was confirmed to be the stable species between 200 and 500<sup>o</sup>C, while mobility of metal ions at higher temperature (>700<sup>o</sup>C) prevented confirmation of the local structure.

Kinetic analysis of Ag particle redispersion into ZSM-5 in the presence of coke using in situ XAFS

2021 ◽  
Author(s):  
Kazumasa Murata ◽  
Junya Ohyama ◽  
Atsushi Satsuma
Keyword(s):  
Fine Structure ◽  
Kinetic Analysis ◽  
X Ray ◽  
Xafs Spectroscopy ◽  
Absorption Fine ◽  
Ag Particles ◽  
In Situ Xafs ◽  
Ag Particle ◽  
X Ray Absorption

In the present study, the redispersion behavior of Ag particles on ZSM-5 in the presence of coke was observed using in situ X-ray absorption fine structure (XAFS) spectroscopy.

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