Nickel-iron layered double hydroxide modified by NiS2/FeS2 with regulated electronic structure as a high-performance catalyst for oxygen evolution reaction

作者：Lu, Yajun; Ma, Feng^*; Mao, Jiayao; Zhang, Haoran; Wang, Jiaxin; Liu, Xingtao; Ren, Xiaohui; Chen, Rongsheng^*

来源：Journal of Alloys and Compounds, 2023, 960: 170842.

DOI：10.1016/j.jallcom.2023.170842

• Water splitting
• Oxygen evolution reaction
• Lithium polysulfide
• Nickel-iron layered double hydroxide
• Structure evolution

Nickel iron layered double hydroxide (LDH) with low cost and high catalytic activity in oxygen evolution reaction (OER) has attracted tremendous research interests. In this work, we report a NiS2/FeS2-decorated Ni-Fe-LDH catalyst (Ni-Fe-LDH/Li2S8-140) synthesized through a sulfidation treatment of Ni-Fe-LDH. The lithium polysulfide (Li2Sx, x = 4, 6, 8) was employed as the sulfur source to treat the Ni-Fe-LDH for the first time. The NiS2 and FeS2 in the obtained Ni-Fe-LDH/Li2S8-140 can adjust the valence state of the Ni and Fe, increase the amount of oxygen vacancies (Vo) and improve the OER kinetics. The Ni-Fe-LDH/Li2S8-140 shows an over -potential of 246 mV at 10 mA cm-2 in alkaline electrolytes with a low Tafel slope of 39.89 mV dec-1. The Ni-Fe-LDH/Li2S8-140 can deliver a constant potential without large variation for over 165 h at 20 mA cm-2. It is interesting that the Ni-Fe-LDH/Li2S8-140 transformed from aggregated nanosheets to long nanowires after duration test. However, the Ni-Fe-LDH still remains the particle morphology after duration test. This structure evolution possibly induced by the NiS2 and FeS2 which may facilitate the charge transfer and benefit the electrolyte penetration can explain the higher stability of Ni-Fe-LDH/Li2S8-140 than that of Ni-Fe-LDH. Besides, the Ni-Fe-LDH/Li2S8-140 was also employed as the anode catalyst for a two-electrode electrolyzer which maintains an output voltage of ca. 1.8 V for over 40 h under the continuous current density of 50 mA cm-2.& COPY; 2023 Elsevier B.V.