Growth of 1T′ MoTe₂ by thermally assisted conversion of electrodeposited tellurium films

Molybdenum ditelluride (MoTe₂) is a transition metal dichalcogenide (TMD) which has two phases stable under ambient conditions, a semiconducting (2H) and semimetallic (1T′) phase. Despite a host of interesting properties and potential applications, MoTe₂ is one of the less-studied TMDs, perhaps due its relatively low abundance in nature or challenges associated with its synthesis, such as the toxicity of most precursors. In this report, we describe the fabrication of thin films of phase-pure 1T′ MoTe₂ using predeposited molybdenum and electrodeposited tellurium layers, at the relatively low temperature of 450 °C. This method allows control over film geometry and over the tellurium concentration during the conversion. The MoTe₂ films are characterized by Raman spectroscopy, X-ray photoelectron spectroscopy, X-ray diffraction, atomic force microscopy, and electron microscopies. When applied as a catalyst for the hydrogen evolution reaction, the films display promising initial results. The MoTe₂ films have a Tafel slope of below 70 mV dec^-1 and compare favorably with other MoTe₂ catalysts reported in the literature, especially considering the inherently scalable fabrication method. The variation in electrocatalytic behavior with thickness and morphology of the films is also investigated.