Dual‐Regulation of Defect Sites and Vertical Conduction by Spiral Domain for Electrocatalytic Hydrogen Evolution

Abstract

Insufficient active sites and weak vertical conduction are the intrinsic factors that restrict the electrocatalytic HER for transition-metal dichalcogenides. As a prototype, we proposed a model of spiral MoTe 2 to optimize collectively the above issues. The conductive atomic force microscopy of an individual spiral reveals that the retentive vertical conduction irrespective of layer thickness benefits from the connected screw dislocation lines between interlayers. Theoretical calculations uncover that the regions near the edge step of the spiral structures more easily form Te vacancies and have lower ΔG H * as extra active sites. A single spiral MoTe 2 -based on-chip microcell was fabricated to extract HER activity and achieved an ultrahigh current density of 3000 mA cm À 2 at an overpotential of 0.4 V, which is about two orders of magnitude higher than the exfoliated counterpart. Profoundly, this unusual spiral model will initiate a new pathway for triggering other inert catalytic reactions.

Unraveling the Role of Defects in Electrocatalysts for Water Splitting: Recent Advances and Perspectives

“…For instance, MoS 2 , a promising electrocatalyst for the HER, had been shown to have active edge sites (Mo sites) and inactive basal planes. , To activate the basal plane, sulfur vacancies have been introduced to expose more Mo sites . In addition, spiral MoTe 2 with screw dislocation was reported as catalysts toward the HER . As a result of its unique structure, active edge sites and as-created tellurium vacancies were fully exposed to promote the HER activity.…”

Refractory‐Metal‐Based Chalcogenides for Energy

“…The superior electrocatalytic activity of MoTe 2 is attributed to i) enhanced vertical conductance due to the structured layer and ii) the Te vacancies distributed in the spiral MoTe 2 created additional active sites for HER. [291] The recent work of Xu et al brought an approach to surfactant-assisted MoSe 2 in electrocatalytic HER. [292] In this report, glucose was selected as a conductive carbon material to support the poor HER performance of MeSe 2 .…”

On-Chip Microdevice Unveils Reactant Enrichment Effect Dominated Electrocatalysis Activity in Molecular-Linked Catalysts

“…The initial current density of a representative device was retained for over 35 min and this stabilization time is acceptable among the on-chip electrochemical microdevices. 31,46 Meanwhile, the OM image after the HER test further reveals a negligible evolution of morphology, suggesting the favorable durability of individual MB/MoS 2 flakes (Figure 2e and Figure S6). The characteristic Raman peak of MB/MoS 2 heterojunction at 1625 cm −1 remained apparent, and the obvious C/N/Cl signals in energy dispersive spectrometry (EDS) elemental mapping images after the HER further reveal the acceptable stability of the MB/MoS 2 heterojunction during the HER (Figure S7).…”