This study reports the facile fabrication of a three-dimensional (3D) spherical composite of Ni^II, Fe^III-layered double hydroxides (NiFe-LDHs)/carbon nanotube (CNT) via the urea synthesis method without any surfactants or organic solvents and applies it to an ethanol electrooxidation reaction for the first time. The spherical composite showed a particle size of approximately 4 μm with NiFe-LDHs sheets that were closely arranged on the sphere surfaces. The formation mechanism of the composite was inferred. First, Ni^II and Fe^III ions were adsorbed on the CNT surface. Simultaneously, the CNT agglomerated into interwoven clusters to form a conductive network. Sequential hydrolysis and polycondensation of Fe^III in the presence of urea were kinetically beneficial to the precipitation of amorphous iron hydroxide. Then, an in situ phase transition from amorphous iron hydroxide to α-FeOOH/Fe(OH)₃ nanoflakes occurred. Surface-adsorbed Ni^II was doped into the α-FeOOH/Fe(OH)₃ flakes. Finally, the NiFe-LDHs nanoflakes continued to crystallize and formed a NiFe-LDHs/CNT spherical composite. Compared to the NiFe-LDHs powder sample, the NiFe-LDHs/CNT composite had enhanced electrocatalytic activity (approximately 5 times), showed a smaller electron transfer resistance of 15.7 Ω, and increased the long-term stability of ethanol oxidation, which could be deduced from the synergistic effect between NiFe-LDHs and CNT.

这项研究报告了通过尿素合成方法，无需任何表面活性剂或有机溶剂，即可轻松地制备Ni ^II，Fe ^III层状双氢氧化物（NiFe-LDHs）/碳纳米管（CNT）的三维（3D）球形复合材料的方法，并将其应用于首次将其用于乙醇电氧化反应。球形复合材料的NiFe-LDHs片紧密排列在球体表面，粒径约为4μm。推测了复合材料的形成机理。首先，Ni ^II和Fe ^III离子被吸附在CNT表面上。同时，CNT聚集成交织的簇以形成导电网络。Fe ^III的顺序水解和缩聚在尿素的存在下对无定形氢​​氧化铁的沉淀在动力学上有利。然后，发生了从无定形氢氧化铁到α-FeO​​OH/ Fe（OH）₃纳米薄片的原位相变。将表面吸附的Ni ^II掺杂到α-FeO​​OH/ Fe（OH）₃薄片中。最后，NiFe-LDHs纳米片继续结晶并形成NiFe-LDHs / CNT球形复合材料。与NiFe-LDHs粉末样品相比，NiFe-LDHs / CNT复合材料具有增强的电催化活性（约5倍），显示出较小的15.7Ω电子传递阻力，并提高了乙醇氧化的长期稳定性，这可能是因为由NiFe-LDHs与CNT之间的协同作用推导得出。