Abstract
Atom-thin transition metal dichalcogenides (TMDs) have emerged as fascinating materials and key structures for electrocatalysis. So far, their edges, dopant heteroatoms and defects have been intensively explored as active sites for the hydrogen evolution reaction (HER) to split water. However, grain boundaries (GBs), a key type of defects in TMDs, have been overlooked due to their low density and large structural variations. Here, we demonstrate the synthesis of wafer-size atom-thin TMD films with an ultra-high-density of GBs, up to ~1012 cm−2. We propose a climb and drive 0D/2D interaction to explain the underlying growth mechanism. The electrocatalytic activity of the nanograin film is comprehensively examined by micro-electrochemical measurements, showing an excellent hydrogen-evolution performance (onset potential: −25 mV and Tafel slope: 54 mV dec−1), thus indicating an intrinsically high activation of the TMD GBs.
Highlights
Atom-thin transition metal dichalcogenides (TMDs) have emerged as fascinating materials and key structures for electrocatalysis
The scanning electron microscopy (SEM) image (Fig. 1d) shows the as-prepared Au QDs with an ultra-high density up to ~2 × 1012 cm−2 and average diameter down to ~4.8 nm, which was achieved by heating a thin Au film on sapphire or SiO2/Si substrates at a high temperature
We investigated the atomic structure of the TMD nanograin films using transmission electron microscopy (TEM)
Summary
Controlled growth of the TMD nanograin film. The main obstacles that hinder the vapor growth of TMDs at the 2D limit to grain sizes typically
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