Amine-assisted Exfoliation and Defects Engineering toward Few-Layer FePS3 Nanosheets for Efficient Hydrogen Evolution

Layered metal phosphorus trichalcogenides (MPX3, M = transition metal, X = S or Se) have been established as new efficient catalysts for water splitting, with FePS3 as one representative example. Here, a novel amine-assisted exfoliation strategy is presented to obtain few-layer FePS3 nanosheets, whose intrinsic electrical conductivity can be easily regulated by adjusting the reaction temperature. The improved electrical conductivity originates from the increase of the Fe3+/Fe2+ ratio, while matrix crystallinity also plays a vital role in this aspect. The combined effect of mixed valence and crystallinity results in superior HER performance with a decrease of the overpotential of 147 mV and a drop of the Tafel slope from 139 mV dec−1 to 94 mV dec−1.