Fig. 4.

a ECSA-normalized polarization curves (symbols) of bare MoS₂ and MoS₂/NiCo-LDH composite catalysts in 1 M KOH solution with the best fits (lines) using the dual-pathway kinetic model. The fitted standard activation free energies are presented in units of meV. b Free energy diagram of the dominant Volmer–Heyrovsky pathway for HER in alkaline electrolyte for bare MoS₂ (blue) and MoS₂/NiCo-LDH composite (red) catalysts. c Schematic illustration of the HER at MoS₂/LDH interface in alkaline environment. Synergistic chemisorption of H (on MoS₂) and OH (on LDH) for enhancing the water dissociation step. Reproduced with permission of the authors of Ref. [44]. Copyright 2017, Cell Press. (Color figure online)