Enhanced Electrocatalytic Hydrogen Evolution from Large-Scale, Facile-Prepared, Highly Crystalline WTe₂ Nanoribbons with Weyl Semimetallic Phase

Tungsten ditellurium (WTe₂) is one of most important layered transition metal dichalcogenides (TMDs) and exhibits various prominent physical properties. All the present methods for WTe₂ preparation need strict conditions such as high temperature or cannot be applied in large scale, which limits its practical applications. In addition, most studies on WTe₂ focus on its physical properties, whereas its electrochemical properties are still illusive with little investigation. Here, we develop a facile and scalable two-step method to synthesize high-quality WTe₂ nanoribbon crystals with 1T' Weyl semimetal phase for the first time. Highly crystalline 1T'-WTe₂ nanoribbons can be obtained on a large scale through this two-step method. In addition, the electrochemical tests show that WTe₂ nanoribbons exhibit smaller overpotential and much better hydrogen evolution reaction catalytic performance than other tungsten-based sulfide and selenide (WS₂, WSe₂) nanoribbons of same morphology and under same preparation conditions. WTe₂ nanoribbons show a Tafel slope of 57 mV/dec, which is one of best values for TMD catalysts and about 2 and 4 times smaller than that for 2H-WS₂ nanoribbons (135 mV/dec) and 2H-WSe₂ nanoribbons (213 mV/dec), respectively. 1T'-WTe₂ nanoribbons also show ultrahigh stability in 5000 cycles and 20 h at 10 mA/cm². The better performance is attributed to high conductivity of semimetallic 1T'-phase-stable WTe₂ nanoribbons with one or two order higher charge-transfer rate than normally semiconducting 2H-stable WS₂ and WSe₂ nanoribbons. These results open the door for electrochemical applications of Weyl semimetallic TMDs.