Lithiation-induced amorphization of Pd3P2S8 for highly efficient hydrogen evolution

Abstract

Engineering material structures at the atomic level is a promising way to tune the physicochemical properties of materials and optimize their performance in various potential applications. Here, we show that the lithiation-induced amorphization of layered crystalline Pd3P2S8 activates this otherwise electrochemically inert material as a highly efficient hydrogen evolution catalyst. Electrochemical lithiation of the layered Pd3P2S8 crystal results in the formation of amorphous lithium-incorporated palladium phosphosulfide nanodots with abundant vacancies. The structure change during the lithiation-induced amorphization process is investigated in detail. The amorphous lithium-incorporated palladium phosphosulfide nanodots exhibit excellent electrocatalytic activity towards the hydrogen evolution reaction with an onset potential of −52 mV, a Tafel slope of 29 mV dec−1 and outstanding long-term stability. Experimental and theoretical investigations reveal that the tuning of morphology and structure of Pd3P2S8 (for example, dimension decrease, crystallinity loss, vacancy formation and lithium incorporation) contribute to the activation of its intrinsically inert electrocatalytic property. This work provides a unique way for structure tuning of a material to effectively manipulate its catalytic properties and functionalities. The structural modification of inactive materials to effectively engineer active catalysts is very attractive. Here, layered crystalline Pd3P2S8 is transformed by electrochemical lithiation into amorphous Li-incorporated nanodots. This process turns the inert parent material into a highly active and stable hydrogen-evolving catalyst.