Single MoTe₂ sheet electrocatalytic microdevice for in situ revealing the activated basal plane sites by vacancies engineering

Activating basal plane inert sites will endow MoTe₂ with prominent hydrogen evolution reaction (HER) catalytic capability and arouse a new family of HER catalysts. Herein, we fabricated single MoTe₂ sheet electrocatalytic microdevice for in situ revealing the activated basal plane sites by vacancies introducing. Through the extraction of electrical parameters of single MoTe₂ sheet, the in-plane and interlayer conductivities were optimized effectively by Te vacancies due to the defect levels. More deeply, Te vacancies can induce the delocalization of electrons around Mo atoms and shift the d-band center, as a consequence, facilitate the adsorption of H from the catalyst surface for HER catalysis. Benefiting by the coordinated regulation of band structure and local charge density, the overpotential at –10 mA∙cm⁻² was reduced to 0.32 V after Te vacancies compared to 0.41 V for the basal plane sites of same MoTe₂ nanosheet. Meanwhile, the insights gained from single nanosheet electrocatalytic microdevice can be applied to the improved HER of the commercial MoTe₂ power. That the in situ testing of the atomic structure-electrical behavior-electrochemical properties of a single nanosheet before/after vacancies introducing provides reliable insight to structure-activity relationships.