Sulfur vacancy riched pure 2H phase VS2 for efficient electrocatalytic hydrogen evolution

We have successfully prepared pure 2H−VS 2 through a facile one-step low-temperature hydrothermal method. The effect of the hydrothermal reaction conditions on the phase and microstructure was investigated. Under the optimal condition, a nano-flower-like 2H−VS 2 material with high crystallinity and rich sulfur vacancy defects was obtained. The product exhibits excellent electrocatalytic HER activity and stability. • We prepared pure 2H–VS 2 through a one-step low-temperature hydrothermal process. • The effect of the reaction conditions on the phase and microstructure was studied. • A nano-flower-like 2H–VS 2 material with rich sulfur vacancy defects is obtained. • The sulfur vacancy riched 2H–VS 2 exhibits excellent HER performance and stability. Vanadium disulfide (VS 2 ), a typical metallic layered transition metal chalcogenide (TMC), has been widely concerned for its high electrical conductivity and reactivity in electrochemical energy storage and conversion applications. The 2H phase VS 2 is expected to exhibit high electrocatalytic activity and be more stable for hydrogen evolution reaction (HER) than the 1T phase structure. But at present, there still lacks a facile method to prepare pure 2H phase VS 2 . Herein, we successfully prepared pure 2H–VS 2 through a simple one-step low-temperature hydrothermal method. We have investigated the effect of the hydrothermal reaction conditions (including the proportion of raw materials and hydrothermal reaction temperatures) on the phase composition and microstructure. Under the optimal condition of 140°C-24 h with a vanadium sulfur ratio of 1:5, a nano-flower-like 2H–VS 2 material with high crystallinity and rich sulfur vacancy defects was obtained. Leveraging these structural advantages, as a demonstration, the product exhibits excellent electrocatalytic HER activity (with η 10 of 181 mV, Tafel slope of 52 mV dec −1 , and J 0 of 67.9 × 10 −3 mA cm −2 ) and stability (it can continuously produce hydrogen for 20 h at a current density of 50 mA cm −2 with ultra-small increased potential of less than 5 mV). This work provides a new way for constructing atomic vacancy defects in layered TMCs for efficient electrocatalysis and is also expected to promote the research of the basic properties of high phase purity TMCs.