Lithium adsorption on 2D transition metal dichalcogenides: towards a descriptor for machine learned materials design

2020 ◽  
Vol 8 (44) ◽  
pp. 23511-23518 ◽  
Author(s):  
Maofeng Dou ◽  
Maria Fyta

Adsorption energy: an efficient descriptor for prediction of single-atom adsorption on 2D TMDs.

2019 ◽  
Vol 25 (S2) ◽  
pp. 172-173
Author(s):  
Chia-Hao Lee ◽  
Chuqiao Shi ◽  
Di Luo ◽  
Abid Khan ◽  
Blanka E. Janicek ◽  
...  

2021 ◽  
Author(s):  
Zhenbin Wang ◽  
Michael Tang ◽  
Ang Cao ◽  
Karen Chan ◽  
Jens Kehlet Nørskov

<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>


Nanomaterials ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 3173
Author(s):  
Weiwei Liu ◽  
Youchao Kong ◽  
Bo Wang ◽  
Xiaoshuang Li ◽  
Pengfei Liu ◽  
...  

Generating clean and sustainable hydrogen from water splitting processes represent a practical alternative to solve the energy crisis. Ultrathin two-dimensional materials exhibit attractive properties as catalysts for hydrogen production owing to their large surface-to-volume ratios and effective chemisorption sites. However, the catalytically inactive surfaces of the transition metal dichalcogenides (TMD) possess merely small areas of active chemical sites on the edge, thus decreasing their possibilities for practical applications. Here, we propose a new class of out-of-plane deformed TMD (cTMD) monolayer to anchor transition metal atoms for the activation of the inert surface. The calculated adsorption energy of metals (e.g., Pt) on curved MoS2 (cMoS2) can be greatly decreased by 72% via adding external compressions, compared to the basal plane. The enlarged diffusion barrier energy indicates that cMoS2 with an enhanced fixation of metals could be a potential candidate as a single atom catalyst (SAC). We made a well-rounded assessment of the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER), which are two key processes in water splitting. The optimized Gibbs free energy of 0.02 for HER and low overpotential of 0.40 V for OER can be achieved when the proper compression and supported metals are selected. Our computational results provide inspiration and guidance towards the experimental design of TMD-based SACs.


Author(s):  
Shufang Tian ◽  
Qing Tang

Recent studies in 2D transition-metal-dichalcogenides (TMDs) for electrocatalytic applications have mainly concentrated on MoS2, while the catalytic properties of the majority of TMDs with other metal compositions remain uncovered. This...


2021 ◽  
Author(s):  
Zhenbin Wang ◽  
Michael Tang ◽  
Ang Cao ◽  
Karen Chan ◽  
Jens Kehlet Nørskov

<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>


2021 ◽  
Author(s):  
Seongjoon Lim ◽  
Shangke Pan ◽  
Kefeng Wang ◽  
Alexey Ushakov ◽  
Ekaterina Sukhanova ◽  
...  

Abstract Intercalation raises manifold possibilities to manipulate the properties of two-dimensional (2D) materials1, and its impact on local electronic/magnetic properties has drawn much attention with the rise of nano-structured 2D materials2,3. Typically, changing an ionic state in a solid involves a dramatic local change of energy as well as orbital/spin magnetic moment from its ground state. However, the atomic investigation of the charging process of an intercalant ion in 2D material has never been explored while such subject has been studied in artificially deposited atoms on thin insulating 2D layers using scanning probe microscopy4–7. Herein, we demonstrate an atomical manipulation of the charge and spin state of Co ions on a metallic NbS2, obtained by cleaving of Co-intercalated NbS2. Density functional theory investigation of various Co configurations reveals that the charging is possible due to a change in the crystal field at the surface and a significant coupling between NbS2 and intercalants occurs via orbitals of the a1g symmetry. The results can be generalized to numerous other combinations of intercalants and base matrixes, suggesting that intercalated transition metal dichalcogenides can be a new platform to introduce single-atom operation 2D electronics/spintronics.


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