CoS 2 -MoS 2 Nanoflower Arrays for Efficient Hydrogen Evolution Reaction in the Universal pH Range.

To explore, highly active electrocatalysts are essential for water splitting materials. Polyoxometalates (POMs) have drawn interesting attention in recent years due to their abundant structure and unique electrocatalytic properties. In this study, by using a POM-based precursor Co2Mo10, novel bimetallic sulfide (CoS 2 -MoS 2 ) nanocomposites are rationally designed and synthesized under hydrothermal conditions. The incorporation of Co 2+ to the host electrocatalyst could effectively increase the exposure of active sites of MoS 2 . Compared to pure MoS 2 , the CoS 2 -MoS 2 nanocomposite exhibited a perfect hydrogen evolution reaction (HER) ability, for it merely requires overpotentials of 120 and 153 mV for 10 mA cm -2 working current density toward the HER in 1 M KOH and 0.5 M H 2 SO 4 electrolyte systems, respectively. Additionally, the nanocomposite exhibited outstanding chemical stability and long-term durability. This study presents a novel strategy that utilizes POMs to enrich the exposed edge sites of MoS 2 , resulting in the preparation of efficient electrocatalysts.