Preparation of ultra-thin and ultra-small nickel-iron layered double hydroxide by acoustic levitation
The development of efficient and low-cost clean energy contributes to the reduction of CO2 emissions.Hydrogen and oxygen pro-duction 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 can expose more active sites and have higher specific surface area.Nickel-iron layered double hydroxide(NiFe-LDH)is a very promising transition metal electrocatalytic catalyst for oxygen evolution reaction(OER).Therefore,NixFe1-LDH(x=1,2,3)precursors were syn-thesized by hydrothermal method,then the ultra-thin and ultra-small LDH nanosheets were quickly synthesized by acoustic levitation.The acoustic levitation method utilizes the high-intensity acoustic radiation force generated between the emitting and reflecting ends of ultra-sound to counteract the gravity of the sample,which in turn levitated the sample.The high acoustic intensity standing wave formed by re-peated superposition of ultrasound waves makes it easier to realize the rapid preparation of ultra-thin and ultra-small nanomaterials.It is found that the Ni1Fe1-LDH precursor could be successfully exfoliated into ultra-thin and ultra-small hydrotalcite nanosheets with only 20 μL formamide within 20 min by acoustic levitation.The transverse size of the Ni1Fe1-LDH precursor is 1 500 nm and the thickness is 25.66 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.It shows excellent OER catalytic performance.For different molar ratios of nickel-iron hydrotalcites,with the increasing of the acoustic levi-tation time,the OER properties is improved.When the current density reaches 10 mA/cm2,the overpotential of Ni1Fe1-LDH-20 min is 309 mV,compared to the overpotential of 673 mV of Ni1Fe1-LDH precursor,it decreases by 364 mV.The tafel slope decreased from 137 to 67 mV/dec,and the electrochemically active surface area was increased by 2.4 times.Compared with other transition metal-based cata-lysts,it demonstrates excellent performance in OER.
NiFe layered double hydroxide(LDH)oxygen evolution reactionacoustic levitationexfoliatingultra-thin and ultra-small nanosheets
万方数据
维普
