Synthesis of 1T WSe 2 on an Oxygen-Containing Substrate Using a Single Precursor.

The metallic property of metastable 1T' WSe 2 and its promising catalytic performance have attracted considerable interest. A hot injection method has been used to synthesize 1T' WSe 2 with a three-dimensional morphology; however, this method requires two or more precursors and long-chain ligands, which inhibit the catalytic performance. Here, we demonstrate the synthesis of 1T' WSe 2 on a substrate by a simple heating-up method using a single precursor, tetraethylammonium tetraselenotungstate [(Et 4 N) 2 WSe 4 ]. The triethylamine produced after the reaction is an electron donor that yields negatively charged WSe 2 , which is stabilized by triethylammonium cations as intercalants between layers and induces 1T' WSe 2 . The purity of 1T' WSe 2 is higher on oxygen-containing crystalline substrates than amorphous substrates because the strong adhesion between WSe 2 and the substrate can produce sufficient triethylammonium (TEA) intercalation. Among the oxygen-containing crystal substrates, the substrate with a lower lattice mismatch with 1T' WSe 2 showed higher 1T' purity due to the uniform TEA intercalation. Furthermore, 1T' WSe 2 on carbon cloth exhibited a more enhanced catalytic performance in the hydrogen evolution reaction (197 mV at 10 mA/cm 2 ) than has been reported previously.