LAUSR

Controlled synthesis of transition metal dichalcogenide (TMD) monolayers with unusual crystal phases has attracted increasing attention due to their promising applications in electrocatalysis. However, the facile and large-scale preparation of TMD monolayers with high-concentration unusual crystal phase still remains a challenge. Herein, we report the synthesis of MoX2 (X = Se or S) monolayers with high-concentration semimetallic 1T′ phase by using the 4H/face-centered cubic (fcc)-Au nanorod as template to form the 4H/fcc-Au@MoX2 nanocomposite. The concentrations of 1T′ phase in the prepared MoSe2 and MoS2 monolayers are up to 86% and 81%, respectively. As a proof-of-concept application, the obtained Au@MoS2 nanocomposite is used for the electrocatalytic hydrogen evolution reaction (HER) in acid medium, exhibiting excellent performance with a low overpotential of 178 mV at the current density of 10 mA/cm2, a small Tafel slope of 43.3 mV/dec, and excellent HER stability. This work paves a way for direct synthesis of TMD monolayers with high-concentration of unusual crystal phase for the electrocatalytic application.