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

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 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 * as extra active sites. A single spiral MoTe -based on-chip microcell was fabricated to extract HER activity and achieved an ultrahigh current density of 3000 mA cm 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.