Design of active nickel single-atom decorated MoS2 as a pH-universal catalyst for hydrogen evolution reaction

MoS2 has been considered as a potential alternative to Pt-based catalysts in the hydrogen evolution reaction (HER). However, the presence of the inactive in-plane domains limits their intrinsic electrocatalytic activity of the catalyst. Here, we demonstrate a new approach for activating these inactive sites and therefore dramatically enhancing the activity. We discover that decorating single Ni atom on MoS2 can increase the HER activity in both alkaline and acidic conditions. Experimental and theoretical results indicate that single Ni atom modifiers are inclined to single dispersion in the S-edge sites and H-basal sites of MoS2, resulting in a favorable change in the adsorption behavior of H atoms on their neighboring S atoms and subsequently the HER activity. Consequently, the single-Ni-atom decorated MoS2 (Ni-SA-MoS2) achieved cathodic current density of 10 mA cm(-2) at over-potentials of 98 mV and 110 mV in 1M KOH and 0.5M H2SO4, respectively. The dispersion of the Ni single atoms in the Ni-SA-MoS2 is unaffected upon 2000 cycles in both acidic and alkaline conditions. This single atom decorating approach presents a facile and promising pathway for designing active electrocatalysts for energy conversion and storage.