Synthesis of vertically aligned wafer-scale tantalum disulfide using high-Ar/H₂S ratio plasma

Nanostructural modification of two-dimensional (2D) materials has attracted significant attention for enhancing hydrogen evolution reaction (HER) activity. In this study, the nanostructure of TaS₂films was controlled by controlling the Ar/H₂S gas ratio used in plasma-enhanced chemical vapor deposition (PECVD). At a high Ar/H₂S gas ratio, vertically aligned TaS₂(V-TaS₂) films were formed over a large-area (4 in) at a temperature of 250 °C, which, to the best of our knowledge, is the lowest temperature reported for PECVD. Furthermore, the plasma species formed in the injected gas at various Ar/H₂S gas ratios were analyzed using optical emission spectroscopy to determine the synthesis mechanism. In addition, the 4 in wafer-scale V-TaS₂was analyzed by x-ray photoelectron spectroscopy, transmission electron microscopy, and atomic force microscopy, and the HER performance of the as-synthesized TaS₂fabricated with various Ar/H₂S ratios was measured. The results revealed that, depending on the film structure of TaS₂, the HER performance can be enhanced owing to its structural advantage. Furthermore, the excellent stability and robustness of V-TaS₂was confirmed by conducting 1000 HER cycles and post-HER material characterization. This study provides important insights into the plasma-assisted nanostructural modification of 2D materials for application as enhanced electrocatalysts.