Synthesis And Characterization Of Nickel-based Chalcogenide Electrocatalysts And Their Application In Hydrogen Evolution Reaction

In this dissertation, our research is about to preparation of nickel-based chalcogenides nanomaterials and their application in hydrogen evolution reaction. The main research results are as following:1. We report on the facile two-step preparation of NiS₂ nanosheets array on carbon cloth as a novel binder-free electrode material for water splitting. As a 3D hydrogen evolution cathode, the NiS₂ nanosheets array electrode has excellent catalytic activity and stability under neutral solutions. It needs overpotentials of 193 and 243 mV to drive current densities of 2 and 10 mA cm-2, respectively. This electrode also performs efficiently in alkaline solutions.2. We demonstrate for the first time that nickel sulfide nanosheets array can be synthesized on Ni foam via a facile one-step low-temperature hydrothermal approach. As an inexpensive 3D electrocatalyst for the hydrogen evolution reaction in both neutral and basic solutions, this electrode is an inexpensive, highly active and stable electrode toward water electrolysis. It only needs overpotentials of 220 and 396 mV to achieve current densities of 10 and 100 mA cm-2 in neutral media and needs overpotentials of 123 and 260 mV to attain current densities of 10 and 100 mA cm-2 in basic electrolyte.3. We report on hydrothermal growth of nickel diselenide nanowall film on carbon cloth through liquid-phase reaction via ion exchange from Ni（OH）2 nanowall film precursor. When tested as an integrated 3D hydrogen-evolving cathode in strongly acidic media, This electrode shows outstanding catalytic activity and strong long-term durability. It displays 10 and 100 mA cm-2 at overpotentials of 145 and 183 mV, respectively.4. We report the in situ growth of NiSe nanowires film on nickel foam（NiSe/NF） by hydrothermal treatment of NF using NaHSe as Se source. When used as a 3D oxygen evolution electrode, the NiSe/NF exhibits high activity with the need of overpotential of 270 mV to achieve 20 mA cm-2 and strong durability in 1.0 M KOH. It is also highly efficient for catalyzing the hydrogen evolution reaction in basic media. This bifunctional electrode enables a high-performance alkaline water electrolyzer with 10 mA cm-2 at a cell voltage of 1.63 V.