The development of efficient and low-cost clean energy contributes to the reduction of CO2 emissions. Hydrogen and oxygen production from electrocatalytic water splitting may be a promising solution to the future demand for clean energy. Among many nanomaterials,ultrathin two - dimensional materials have shown excellent performance in electrocatalytic reactions due to the fact that they canexpose more active sites and have higher specific surface area. Nickel-iron layered double hydroxide (NiFe-LDH) is a very promisingtransition metal electrocatalytic catalyst for oxygen evolution reaction (OER). Therefore, NixFe1-LDH(x = 1,2,3) precursors were synthesized by hydrothermal method, then the ultra-thin and ultra-small LDH nanosheets were quickly synthesized by acoustic levitation. Theacoustic levitation method utilizes the high-intensity acoustic radiation force generated between the emitting and reflecting ends of ultrasound to counteract the gravity of the sample, which in turn levitated the sample. The high acoustic intensity standing wave formed by repeated superposition of ultrasound waves makes it easier to realize the rapid preparation of ultra-thin and ultra-small nanomaterials. It isfound that the Ni1Fe1-LDH precursor could be successfully exfoliated into ultra-thin and ultra-small hydrotalcite nanosheets with only20 μL formamide within 20 min by acoustic levitation. The transverse size of the Ni1Fe1-LDH precursor is 1 500 nm and the thickness is25.66 nm. The ultra-thin and ultra-small Ni1Fe1 -LDH-20 min transverse size is 10 nm, and the thickness is as low as 0.649 nm. Itshows excellent OER catalytic performance. For different molar ratios of nickel-iron hydrotalcites, with the increasing of the acoustic levitation time, the OER properties is improved. When the current density reaches 10 mA/ cm2, the overpotential of Ni1Fe1-LDH-20 min is309 mV, compared to the overpotential of 673 mV of Ni1Fe1-LDH precursor, it decreases by 364 mV. The tafel slope decreased from 137to 67 mV/ dec, and the electrochemically active surface area was increased by 2.4 times. Compared with other transition metal-based catalysts, it demonstrates excellent performance in OER.

加晓丹(1989—),女,陕西榆林人,副教授,博士。E-mail:jiaxiaodan1989@163.com

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JIA Xiaodan,LI Jinlong,ZHANG Shaobing,et al.Preparation of ultra-thin and ultra-small nickel-iron layered double hydroxide by acoustic levitation[J].Clean Coal Technology,2024,30(4):120-129.