Abstract Co3O4 nanoflowers (NFs) were obtained from cobalt hydroxide coated on silica, Co(OH)2@SiO2, prepared from a homogenous mixture of urea and cobalt nitrate in an aqueous solution. The Co3O4@SiO2 was obtained by calcining Co(OH)2@SiO2 under atmospheric air for 3 h and then immersing in sodium hydroxide to yield Co3O4-NFs. The Ni-deposited Co3O4 NFs (Ni@Co3O4-NFs) were synthesized by chemical deposition of nickel nanoparticles onto Co3O4-NF by a reducing agent, NaBH4. The physical characterization of Co3O4-NFs and Ni@Co3O4-NFs was performed by Brunauer-Emmett-Teller analysis, scanning electron microscopy and X-ray diffraction. The electrochemical properties of Co3O4-NFs and Ni@Co3O4-NFs for the oxygen reduction and evolution reaction were determined in an 8 M KOH solution. Ni@Co3O4-NF showed a better cell performance than that of Co3O4-NF. Moreover, Ni@Co3O4-NF exhibited a higher stability and longer life cycles at 20 mA cm−2 at a 2 h charging and discharging rate as compared to Co3O4-NF. Therefore, Co3O4-NF and Ni@Co3O4-NF could be used as a cathode material for Zn-air rechargeable batteries.

中文翻译：

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高度多孔的 Co3O4 和 Ni 沉积的 Co3O4 纳米花作为氧还原和析出反应的双功能催化剂

摘要 Co3O4 纳米花 (NFs) 由涂覆在二氧化硅上的氢氧化钴获得，Co(OH)2@SiO2，由尿素和硝酸钴在水溶液中的均匀混合物制备。Co(OH)2@SiO2 在大气中煅烧 3 小时，然后浸入氢氧化钠中得到 Co3O4-NFs，得到 Co3O4@SiO2。Ni 沉积的 Co3O4 NFs（Ni@Co3O4-NFs）是通过还原剂 NaBH4 将镍纳米颗粒化学沉积到 Co3O4-NF 上来合成的。Co3O4-NFs 和 Ni@Co3O4-NFs 的物理表征通过 Brunauer-Emmett-Teller 分析、扫描电子显微镜和 X 射线衍射进行。Co3O4-NFs 和 Ni@Co3O4-NFs 在氧还原和析出反应中的电化学性质在 8 M KOH 溶液中测定。Ni@Co3O4-NF 表现出比 Co3O4-NF 更好的电池性能。此外，与 Co3O4-NF 相比，Ni@Co3O4-NF 在 20 mA cm-2 下在 2 h 充放电速率下表现出更高的稳定性和更长的生命周期。因此，Co3O4-NF 和 Ni@Co3O4-NF 可用作锌空气可充电电池的正极材料。