In-situ derived highly active NiS2 and MoS2 nanosheets on NiMoO4 microcuboids via controlled surface sulfidation for high-current-density hydrogen evolution reaction

Abstracts In this work, we highlight the significances of Controlled Surface Sulfidation (CSS) for high-current-density hydrogen evolution reaction (HER) with bimetallic NiMoO4 microcuboids supported on Ni foam. It reveals that a new phase 1T’-MoS2 is derived in-situ from the surface NiMoO4 microcuboids during CSS in addition to pyrite-phase NiS2 and 2H-MoS2 as obtained from full sulfidation. We denote the controlled sulfided sample as “CSS-NiS2/MoS2” and the fully sulfided sample as “FS-NiS2/MoS2”, respectively. The CSS-NiS2/MoS2 electrode only required low overpotentials of 12, 47, 112 mV to drive -10, -20, -100 mA cm−2, respectively, which surpasses the FS-NiS2/MoS2 considerably (54, 90, 195 mV at -10, -20, -100 mA cm−2, respectively). Notably, it delivers a high current density of -500 and -1000 mA cm−2 at low overpotentials of only 200 and 264 mV, respectively. The durability of the high-current-density activity of CSS-NiS2/MoS2 is also proven over 50 h of stability test. The excellent performances of CSS-NiS2/MoS2 may be synergistically contributed from the active phases and the design dual hierarchical (i.e., 2D-nano/1D-microhybrids) structure. The CSS may serve as an effective strategy to modulate the electrochemical properties of materials holding great promises for the applications of next-generation energy storage and conversion.