The possible hydridic nature of adsorbed hydrogen in the hydrogen evolution reaction

1973 ◽  
Vol 44 (1) ◽  
pp. 47-51 ◽  
Author(s):  
Donald J. Barclay
Keyword(s):  
Hydrogen Evolution ◽  
Hydrogen Evolution Reaction ◽  
Adsorbed Hydrogen

scholarly journals Atoms vs. Ions: Intermediates in Reversible Electrochemical Hydrogen Evolution Reaction

Catalysts ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 1135
Author(s):  
Jurga Juodkazytė ◽  
Kȩstutis Juodkazis ◽  
Saulius Juodkazis
Keyword(s):  
Electron Transfer ◽  
Hydrogen Evolution ◽  
Hydrogen Evolution Reaction ◽  
Ionic Species ◽  
Absolute Temperature ◽  
Main Reaction ◽  
Adsorbed Hydrogen ◽  
H2 Evolution ◽  
Hydrogen Electrode ◽  
Reported Data

We present a critical analysis of the mechanism of reversible hydrogen evolution reaction based on thermodynamics of hydrogen processes considering atomic and ionic species as intermediates. Clear distinction between molecular hydrogen evolution/oxidation (H2ER and H2OR) and atomic hydrogen evolution/oxidation (HER and HOR) reactions is made. It is suggested that the main reaction describing reversible H2ER and H2OR in acidic and basic solutions is: H3O++2e−⇌(H2+)adH2+OH− and its standard potential is E0 = −0.413 V (vs. standard hydrogen electrode, SHE). We analyse experimentally reported data with models which provide a quantitative match (R.J.Kriek et al., Electrochem. Sci. Adv. e2100041 (2021)). Presented analysis implies that reversible H2 evolution is a two-electron transfer process which proceeds via the stage of adsorbed hydrogen molecular ion H2+ as intermediate, rather than Had as postulated in the Volmer-Heyrovsky-Tafel mechanism. We demonstrate that in theory, two slopes of potential vs. lg(current) plots are feasible in the discussed reversible region of H2 evolution: 2.3RT/F≈60 mV and 2.3RT/2F≈30 mV, which is corroborated by the results of electrocatalytic hydrogen evolution studies reported in the literature. Upon transition to irreversible H2ER, slowdown of H2+ formation in the first electron transfer stage manifests, and the slope increases to 2.3RT/0.5F≈120 mV; R,F,T are the universal gas, Faraday constants and absolute temperature, respectively.

scholarly journals How Stable Are 2H-MoS2 Edges Under Hydrogen Evolution Reaction Conditions?

2021 ◽  
Author(s):  
Nawras Abidi ◽  
Audrey Bonduelle-Skrzypczak ◽  
Stephan Steinmann
Keyword(s):  
Hydrogen Evolution ◽  
Hydrogen Evolution Reaction ◽  
Active Sites ◽  
Density Functional ◽  
External Source ◽  
Operating Conditions ◽  
Adsorbed Hydrogen ◽  
Functional Theory ◽  
Acidic Conditions

MoS<sub>2</sub>, have emerged as a promising class of electrocatalysts for the production of H<sub>2</sub> via the hydrogen evolution reaction (HER) in acidic conditions.<div>The edges of MoS<sub>2</sub> are known for their HER activity, but their precise atomistic nature and stability under HER conditions is not yet known. In contrast to other typical uses of MoS<sub>2</sub> as a catalyst, under HER there is no external source of sulfur. Therefore, the sulfidation of the edges can only decrease under operating conditions and the thermodynamics of the process are somewhat ill-defined. Our results suggest that the 50%S S-edge may be active for HER via the Volmer-Tafel mechanism and is, despite a high H coverage, stable with respect to H<sub>2</sub>S release. </div><div>At the 50%S Mo-edge, the adsorbed hydrogen opens the way for H<sub>2</sub>S release, leading to the 0%S Mo-edge, which was previously investigated and found to be HER active. HER being a water-based process, we also considered the effect of the presence of H<sub>2</sub>O and the in-situ formation of OH. For the 50%S Mo-edge, H<sub>2</sub>O is only very weakly adsorbed and OH formation is unfavorable. Nevertheless, OH assists the loss of sulfur coverage, leading to OH-based HER active sites. In contrast, OH is strongly adsorbed on the 50%S S-edge. By explicitly considering the electrochemical potential using grand-canonical density functional theory, we unveil that the Volmer-Heyrovsky mechanism on sulfur sites is still accessible in the presence of surface OH at the 50%S S-edge. However, the 50%S S-edge is found to be mildly unstable with respect to H<sub>2</sub>S in the presence of water/OH. Hence, we suggest that the 50%S S-edge evolves over time towards a 0%S S-edge, covered by surface OH that will block permanently the active sites. </div>

scholarly journals Insights into Hydrogen Evolution Reaction on 2D Transition Metal Dichalcogenides

2021 ◽  
Author(s):  
Zhenbin Wang ◽  
Michael Tang ◽  
Ang Cao ◽  
Karen Chan ◽  
Jens Kehlet Nørskov
Keyword(s):  
Transition Metal ◽  
Hydrogen Evolution ◽  
Hydrogen Evolution Reaction ◽  
Adsorption Energy ◽  
Density Functional ◽  
Hydrogen Adsorption ◽  
Activation Barrier ◽  
Transition Metal Dichalcogenides ◽  
Adsorbed Hydrogen ◽  
Metal Dichalcogenides

<p>Understanding the hydrogen evolution reaction (HER) behaviors over 2D transition metal dichalcogenides (2D-TMDs) is critical for the development of non-precious HER electrocatalysts with better activity. In this work, by combining density functional theory calculations with microkinetic modelling, we thoroughly investigated the HER mechanism on 2D-TMDs. We find there is an important dependence of simulated cell size on the calculated hydrogen adsorption energy and the activation barrier for MoS<sub>2</sub>. Distinct from previous “H migration” mechanisms proposed for the Heyrovsky reaction − the rate-determining step for MoS<sub>2</sub>, we propose the Mo site only serves as the stabilized transition state rather than H adsorption. In comparison to transition metal electrocatalysts, we find that the activation barrier of the Heyrovsky reaction on 2D-TMDs scales with the hydrogen adsorption energy exactly as for transition metals except that all activation energies are displaced upwards by <i>ca.</i> 0.4 eV. This higher Heyrovsky activation barrier is responsible for the substantially lower activity of 2D-TMDs. We further show that this higher activation barrier stems from the more positively charged adsorbed hydrogen on the chalcogenides interacting repulsively with the incoming proton. Based on these insights, we discuss potential strategies for the design of non-precious HER catalysts with activity comparable to Pt.</p>

Influence of adsorption of organic compounds and surface heterogeneity on the hydrogen evolution reaction

1997 ◽  
Vol 75 (11) ◽  
pp. 1615-1623 ◽  
Author(s):  
Andrzej Lasia
Keyword(s):  
Kinetic Parameters ◽  
Hydrogen Evolution ◽  
Organic Compounds ◽  
Hydrogen Evolution Reaction ◽  
Surface Heterogeneity ◽  
Adsorbed Hydrogen ◽  
Heterogeneous Surfaces ◽  
Tafel Slopes ◽  
Adsorption Energies ◽  
Temkin Adsorption Isotherm

The hydrogen evolution reaction on rough or porous surfaces often leads to low Tafel slopes that cannot be explained in terms of the Volmer–Heyrovsky–Tafel mechanism. In addition, adsorption of organic compounds and ions causes an increase in the Tafel slopes. To explain such behavior, a concept of distribution of adsorption energies on heterogeneous surfaces, leading to a distributed kinetics, was studied. Simulations of the dependence of the current and the surface coverage by adsorbed hydrogen on overpotential are presented for different values of the kinetic parameters in the absence and presence of the adsorbed foreign substances. These results were compared with those obtained using the Frumkin/Temkin adsorption isotherm. It was found that for some kinetic parameters and a flat distribution of adsorption energies, low Tafel slopes, similar to those observed experimentally, are obtained. Keywords: hydrogen evolution, adsorption, heterogeneous surfaces, distributed kinetics, Frumkin/Temkin isotherm.

scholarly journals On the extrema on the potential dependence of the charge transfer resistance in the hydrogen evolution reaction

2021 ◽  
Vol 11 (2) ◽  
pp. 154-164
Author(s):  
Vladimir I. Kichigin ◽  
Keyword(s):  
Charge Transfer ◽  
Kinetic Parameters ◽  
Hydrogen Evolution ◽  
Hydrogen Evolution Reaction ◽  
Charge Transfer Resistance ◽  
Adsorbed Hydrogen ◽  
Transfer Coefficients ◽  
Transfer Resistance ◽  
Kinetic Information ◽  
Cathodic Region

The shape of the charge transfer resistance Rct versus overpotentialh curves for the hydrogen evolution reaction (Volmer – Heyrovsky mechanism, Langmuir isotherm for adsorbed hydrogen) was analyzed. It was shown that, depending on the kinetic parameters of reaction steps, three cases are possible: (i) there are no extrema on these curves; (ii) there is one maximum; (iii) there are a minimum and a maximum. Some ways for obtaining kinetic parameters from the curves with extrema are discussed. It was shown that the rate constants and transfer coefficients of all steps can be determined from logRct–h curve alone if there are a minimum and maximum of Rct in cathodic region. In the absence of the extrema, the amount of kinetic information gained from logRct–h plots is considerably reduced.

scholarly journals Insights into Hydrogen Evolution Reaction on 2D Transition Metal Dichalcogenides

2021 ◽  
Author(s):  
Zhenbin Wang ◽  
Michael Tang ◽  
Ang Cao ◽  
Karen Chan ◽  
Jens Kehlet Nørskov
Keyword(s):  
Transition Metal ◽  
Hydrogen Evolution ◽  
Hydrogen Evolution Reaction ◽  
Adsorption Energy ◽  
Density Functional ◽  
Hydrogen Adsorption ◽  
Activation Barrier ◽  
Transition Metal Dichalcogenides ◽  
Adsorbed Hydrogen ◽  
Metal Dichalcogenides

<p>Understanding the hydrogen evolution reaction (HER) behaviors over 2D transition metal dichalcogenides (2D-TMDs) is critical for the development of non-precious HER electrocatalysts with better activity. In this work, by combining density functional theory calculations with microkinetic modelling, we thoroughly investigated the HER mechanism on 2D-TMDs. We find there is an important dependence of simulated cell size on the calculated hydrogen adsorption energy and the activation barrier for MoS<sub>2</sub>. Distinct from previous “H migration” mechanisms proposed for the Heyrovsky reaction − the rate-determining step for MoS<sub>2</sub>, we propose the Mo site only serves as the stabilized transition state rather than H adsorption. In comparison to transition metal electrocatalysts, we find that the activation barrier of the Heyrovsky reaction on 2D-TMDs scales with the hydrogen adsorption energy exactly as for transition metals except that all activation energies are displaced upwards by <i>ca.</i> 0.4 eV. This higher Heyrovsky activation barrier is responsible for the substantially lower activity of 2D-TMDs. We further show that this higher activation barrier stems from the more positively charged adsorbed hydrogen on the chalcogenides interacting repulsively with the incoming proton. Based on these insights, we discuss potential strategies for the design of non-precious HER catalysts with activity comparable to Pt.</p>

Nitrogen-induced interfacial electronic structure with optimized water and hydrogen binding abilities for efficient alkaline hydrogen evolution electrocatalysis

2021 ◽  
Author(s):  
Bocheng Qiu ◽  
Yuefeng Zhang ◽  
Xuyun Guo ◽  
Yingxin Ma ◽  
Mengmeng Du ◽  
...  
Keyword(s):  
Electronic Structure ◽  
Hydrogen Evolution ◽  
Hydrogen Evolution Reaction ◽  
Strong Correlation ◽  
High Performance ◽  
Adsorbed Hydrogen ◽  
Hydrogen Binding ◽  
Hydrogen Atoms ◽  
Interfacial Electronic Structure ◽  
Catalytic Sites

Fabricating heterostructures with dense interfacial catalytic sites is vitally essential for implementation of high-performance hydrogen evolution reaction (HER). However, the strong correlation between the adsorbed hydrogen atoms and electronegative nonmetal...

scholarly journals How Stable Are 2H-MoS2 Edges Under Hydrogen Evolution Reaction Conditions?

2021 ◽  
Author(s):  
Nawras Abidi ◽  
Audrey Bonduelle-Skrzypczak ◽  
Stephan Steinmann
Keyword(s):  
Hydrogen Evolution ◽  
Hydrogen Evolution Reaction ◽  
Active Sites ◽  
Density Functional ◽  
External Source ◽  
Operating Conditions ◽  
Adsorbed Hydrogen ◽  
Functional Theory ◽  
Acidic Conditions

MoS<sub>2</sub>, have emerged as a promising class of electrocatalysts for the production of H<sub>2</sub> via the hydrogen evolution reaction (HER) in acidic conditions.<div>The edges of MoS<sub>2</sub> are known for their HER activity, but their precise atomistic nature and stability under HER conditions is not yet known. In contrast to other typical uses of MoS<sub>2</sub> as a catalyst, under HER there is no external source of sulfur. Therefore, the sulfidation of the edges can only decrease under operating conditions and the thermodynamics of the process are somewhat ill-defined. Our results suggest that the 50%S S-edge may be active for HER via the Volmer-Tafel mechanism and is, despite a high H coverage, stable with respect to H<sub>2</sub>S release. </div><div>At the 50%S Mo-edge, the adsorbed hydrogen opens the way for H<sub>2</sub>S release, leading to the 0%S Mo-edge, which was previously investigated and found to be HER active. HER being a water-based process, we also considered the effect of the presence of H<sub>2</sub>O and the in-situ formation of OH. For the 50%S Mo-edge, H<sub>2</sub>O is only very weakly adsorbed and OH formation is unfavorable. Nevertheless, OH assists the loss of sulfur coverage, leading to OH-based HER active sites. In contrast, OH is strongly adsorbed on the 50%S S-edge. By explicitly considering the electrochemical potential using grand-canonical density functional theory, we unveil that the Volmer-Heyrovsky mechanism on sulfur sites is still accessible in the presence of surface OH at the 50%S S-edge. However, the 50%S S-edge is found to be mildly unstable with respect to H<sub>2</sub>S in the presence of water/OH. Hence, we suggest that the 50%S S-edge evolves over time towards a 0%S S-edge, covered by surface OH that will block permanently the active sites. </div>

A crystalline–amorphous Ni–Ni(OH)2 core–shell catalyst for the alkaline hydrogen evolution reaction

2020 ◽  
Vol 8 (44) ◽  
pp. 23323-23329
Author(s):  
Jing Hu ◽  
Siwei Li ◽  
Yuzhi Li ◽  
Jing Wang ◽  
Yunchen Du ◽  
...  
Keyword(s):  
Hydrogen Evolution ◽  
Hydrogen Evolution Reaction ◽  
Electrocatalytic Activity ◽  
Core Shell ◽  
Alkaline Conditions

Crystalline–amorphous Ni–Ni(OH)2 core–shell assembled nanosheets exhibit outstanding electrocatalytic activity and stability for hydrogen evolution under alkaline conditions.

Sign in / Sign up

Export Citation Format

Share Document