Single-crystalline WSe2 nanoflakes as efficient electrocatalysts

Abstract

This study presents a novel single molecular source with covalently bonded ligand systems, featuring pre-existing W–Se bonds, for direct synthesis of single crystalline flakes of 2D tungsten diselenide (WSe₂). Synthesis and structural characterization of [W{(SeC₂H₄)₂NMe}₂] expand the class of single- source precursors for metal sulfides and selenides of general formula [M^IV{(XC₂H₄)₂NMe}₂] (M^IV = Ti, Zr, Hf, Mo, W, Sn; X = S, Se). Comprehensive analysis including NMR, elemental analysis, and single crystal X-ray diffraction, provide insights into structural characteristics of [W{(SeC₂H₄)₂NMe}₂] in solution and solid state. Microwave-assisted solvothermal decomposition at 300 °C for 15 minutes yielded highly crystalline WSe₂ flakes, confirmed by XRD, SEM, EDS, and TEM analyses. Reduced reaction time under mild conditions enables reproducible generation of layered 2D WSe₂ materials for large-scale applications. Electrochemical studies reveal increased electrocatalytic activity, attributed to enhanced electrochemical surface area (ECSA, 67.3 cm²) observed in the as-prepared WSe₂ flower-like nanostructures.