Amine and Carbon-pretreated nickel–molybdenum disulfide as bifunctional electrocatalysts for hydrogen and oxygen gas evolution

We report the synthesis and characterization of a variety of nickel molybdenum disulfide (NiMoS2) materials as efficient bifunctional electrocatalysts for both the hydrogen evolution and oxygen evolution reactions (HER and OER, respectively). These catalysts were obtained from pretreated ammonium tetrathiomolybdate (ATM) using ethylenediamine (EDA), diethylenetriamine (DETA), or carbon nanotubes (CNT), which were further reacted with Ni(NO3)2. All the materials were characterized by scanning electron microscopy (SEM) and powder X-ray diffraction (pXRD), and all materials were evaluated as both HER and OER electrocatalysts. The NiMoS2 synthesized from DETA-pretreatment exhibits the best HER catalytic performance with the lowest overpotential of 0.151 V, while the CNT-modified NiMoS2 shows the lowest OER overpotential of 0.310 V. All the pretreated NiMoS2 electrocatalysts show significantly improved catalytic activity compared to the one prepared directly from pristine ATM precursor.