Nanostructured hydrotreating catalysts for electrochemical hydrogen evolution

Question

1. What are the contributions mentioned in the paper "Nanostructured hydrotreating catalysts for electrochemical hydrogen evolution" ?

2. What are the main approaches to increase the activity of the molecular hydrogen?

3. What is the challenge of using moS2 sheets?

4. What is the effect of Au nanoparticles on the HER?

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Here the authors present an overview of recent developments of the non-noble metal catalysts for electrochemical hydrogen evolution reaction ( HER ).. Emphasis is given to the nanostructuring of industrially relevant hydrotreating catalysts as potential HER electrocatalysts.

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High-aspect ratio architectures have been used to improve the activity per geometric area and to maximize the diffusion of protons and molecular hydrogen.

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A challenge encountered when using chemically exfoliated MoS2 sheets is their tendency to restack during material processing, which hinders vertical charge transport and limits the access of protons to the catalytically active sites.

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The presence of Au nanoparticles on the chemically exfoliated nanosheets greatly improves charge transport between the sheets and enhances their catalytic HER efficiency.

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The authors also proposed that the anchoring of Mo2C on the carbon support downshifts the d-band center of molybdenum which decreases the hydrogen binding energy.

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At the same time, the quality of future crude oil feedstock is expected to deteriorate due to the lower availability of light petroleum.

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The Fe-WCN exhibits several desirable features: (1) it consists of uniform and small nanoparticles (10-20 nm); (2) it has a nitrogen-rich backbone; (3) it has a pure tungsten carbonitride crystal structure.

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Using carbon black and carbon nanotubes (CNT) as support, Chen et al. prepared Mo2C nanoparticles with an average size of 12 nm.63

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In addition to the intrinsic activity which is related to TOF, the current density also depends on the loading of catalyst per area and the density of active sites.

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Variation of the crystallization temperature showed that lower temperature facilitates the formation of oxygen-incorporated ultrathin nanosheets.

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On the other hand, metals to the right of Pt binds hydrogen too weakly, failing to stabilize the intermediate state and preventing any reaction from taking place.

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In the ideal case, where TS0 is supplied by an external source, the application of only 1.23V of external potential would be sufficient to start water splitting in an electrochemical cell.

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To achieve a current density of 10 mA cm-2, the former catalyst requires 200 mV of overpotential, while the latter requires only 160 mV.

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The improvement brought by the RGO support might be attributed to a higher conductivity of the system and the coupling of RGO with catalyst.

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The nanosheets prepared at lower temperatures have an improved conductivity and exhibit simultaneously a high number of active sites and a good conductivity.

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This electrode achieved a current density of 10 mA cm-2 at = 187 mV and a Tafel slope of 43 mV dec-1.52 Cui and co-workers recently reported the continuous tuning of vertically aligned MoS2 nanofilms through electrochemical8 | Chem.

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In that seminal work, Mo-edge sites were identified as active sites for HER; the theoretical free energy of adsorption of hydrogen on this metallic edge is similar to those of Pt and the active sites of hydrogenases.

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A second contribution comes from the enhanced electron transport by coupling graphene sheets to the less-conductive MoS2 nanoparticles.

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A second approach is to use porous and conductive support such as carbon nanotubes to improve the conductivity of the catalytic system and to favour the dispersion of catalyst.

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In strong contrast to aggregated MoS2 particles grown freely in solution without GO, the MoS2/RGO hybrid exhibited superior electrocatalytic HER activity relative to other MoS2 catalysts (Fig. 6).

Nanostructured hydrotreating catalysts for electrochemical hydrogen evolution

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Most frequently asked questions

1. What are the contributions mentioned in the paper "Nanostructured hydrotreating catalysts for electrochemical hydrogen evolution" ?

2. What are the main approaches to increase the activity of the molecular hydrogen?

3. What is the challenge of using moS2 sheets?

4. What is the effect of Au nanoparticles on the HER?

5. What is the effect of the anchoring of Mo2C on the carbon support?

6. What is the main reason for the decline in the quality of crude oil feedstock?

7. What is the description of Fe-WCN?

8. How did Chen and Schröder prepare Mo2C nanoparticles?

9. What is the effect of catalyst loading on the current density of a molecular catalyst?

10. What is the effect of the temperature on the formation of ultrathin nanosheets?

11. What is the effect of metals to the right of Pt on the HER?

12. What is the ideal voltage for water splitting in an electrochemical cell?

13. How many mV of overpotential does a catalyst need?

14. What is the effect of the RGO support on the HER activity of Mo1Soy?

15. What is the way to prepare a moS2 nanosheet?

16. How did they achieve the continuous tuning of MoS2 nanofilms?

17. What is the theoretical free energy of adsorption of hydrogen on the metallic edge?

18. What is the second contribution to the HER activity of the MoS2 hybrid?

19. What is the way to improve the conductivity of Mo2C?

20. What is the HER activity of the MoS2/RGO hybrid?

Figures

Citations

Spatially Confined Assembly of Monodisperse Ruthenium Nanoclusters in a Hierarchically Ordered Carbon Electrode for Efficient Hydrogen Evolution.

Engineered MoSe2-based heterostructures for efficient electrochemical hydrogen evolution reaction

Recent Advances in Carbon‐Supported Noble‐Metal Electrocatalysts for Hydrogen Evolution Reaction: Syntheses, Structures, and Properties

Decoration of the inert basal plane of defect-rich MoS2 with Pd atoms for achieving Pt-similar HER activity

2D Transition Metal Dichalcogenides‐Based Electrocatalysts for Hydrogen Evolution Reaction

References

I and i

Photoelectrochemical cells : Materials for clean energy

The chemistry of two-dimensional layered transition metal dichalcogenide nanosheets

Two-Dimensional Nanosheets Produced by Liquid Exfoliation of Layered Materials

Identification of active edge sites for electrochemical H2 evolution from MoS2 nanocatalysts.

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