School of Environment and Energy, South China University of Technology, Guangzhou 510006, China.
Nanoscale. 2018 Apr 26;10(16):7746-7758. doi: 10.1039/c8nr00147b.
A generic hydrothermal synthesis route has been successfully designed and utilized to in situ grow highly ordered Co3O4 nanoarray (NA) precursors on Ni substrates, forming a series of Co3O4 nanoarray-based monolithic catalysts with subsequent calcination. The morphology evolution of Co3O4 nanostructures which depends upon the reaction time, with and without CTAB or NH4F is investigated in detail, which is used to further demonstrate the growth mechanism of Co3O4 nanoarrays with different morphologies. CO is chosen as a probe molecule to evaluate the catalytic performance over the synthesized Co-based oxide catalysts, and the effect of morphological transformation on the catalytic activity is further confirmed via using TEM, H2-TPR, XPS, Raman spectroscopy and in situ Raman spectroscopy. As a proof of concept application, core-shell Co3O4 NAs-8 presenting hierarchical nanosheets@nanoneedle arrays with a low density of nanoneedles exhibits the highest catalytic activity and long-term stability due to its low-temperature reducibility, the lattice distortion of the spinel structure and the abundance of surface-adsorbed oxygen (Oads). It is confirmed that CO oxidation on the surface of Co3O4 can proceed through the Langmuir-Hinshelwood mechanism via using in situ Raman spectroscopy. It is expected that the in situ synthesis of well-defined Co3O4 monolithic catalysts can be extended to the development of environmentally-friendly and highly active integral materials for practical industrial catalysis.
一种通用的水热合成路线被成功设计并应用于原位生长高度有序的 Co3O4 纳米阵列（NA）前体在 Ni 基底上，形成一系列具有后续煅烧的 Co3O4 纳米阵列基整体催化剂。详细研究了 Co3O4 纳米结构的形态演变，这取决于反应时间、是否有 CTAB 或 NH4F，用于进一步证明具有不同形态的 Co3O4 纳米阵列的生长机制。选择 CO 作为探针分子来评估合成的 Co 基氧化物催化剂的催化性能，通过 TEM、H2-TPR、XPS、拉曼光谱和原位拉曼光谱进一步证实了形态转变对催化活性的影响。作为概念验证应用，具有低密度纳米针的分层纳米片@纳米针阵列的核壳 Co3O4 NAs-8 表现出最高的催化活性和长期稳定性，这归因于其低温还原性、尖晶石结构的晶格畸变和表面吸附氧（Oads）的丰富性。通过原位拉曼光谱证实了 CO 在 Co3O4 表面上的氧化可以通过 Langmuir-Hinshelwood 机制进行。预计，通过原位合成具有明确形貌的 Co3O4 整体催化剂，可以扩展到开发用于实际工业催化的环保和高活性整体材料。
