Gold nanodots-decoration stabilizes and activates metastable metallic phase MoS₂ nanosheets for efficient hydrogen evolution reaction

Hydrogen evolution reaction (HER), an efficient and sustainable method for clean hydrogen energy producing, has been impeded by scarcity and costly of precious metals electrocatalysts. Two-dimensional (2D) metallic phase MoS₂ (M-MoS₂) nanosheets (NSs) have been identified as cost-effective and efficient alternative electrocatalysts for HER. However, the practical applications of M-MoS₂ NSs are often limited by the metastable property of their metallic phase. Here, we demonstrate both the metallic phase stability and the electrocatalytic activity of the M-MoS₂ NSs can be dramatically improved by gold (Au) nanodots (NDs) decoration. The obtained Au NDs decorated M-MoS₂ NSs (namely, Au NDs@M-MoS₂ NSs) maintain well their metallic phase even after about 100 days storage, while the M-MoS₂ NSs have already transferred to dominant 2H phase one for about 2 weeks. The results of first-principles density functional theory (DFT) calculation also indicate that the Au NDs modification can stabilize the metastable metallic phase of M-MoS₂ NSs. Moreover, the as-prepared Au NDs@M-MoS₂ NSs also show remarkable enhanced electrocatalytic activity toward HER. These findings may open up an ideal approach to stabilize and activate the metastable metallic phase 2D transition metal dichalcogenides-based electrocatalysts for various promising applications.