How addition of a nickel cyclohexyl-salen complex impacts a one-pot synthesis of nickel/hierarchically porous carbon monolith catalyst
How addition of a nickel cyclohexyl-salen complex impacts a one-pot synthesis of nickel/hierarchically porous carbon monolith catalyst
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DOI：
10.1007/s10971-020-05436-3
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发表时间：
2020-11
影响因子：
2.5
通讯作者：
Rina Adhikari;Trupti V. Kotbagi;K. H. Shaughnessy;Ambar B. Shrestha;J. Sherwood;Y. Bao;M. Bakker
中科院分区：
文献类型：
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作者：
Rina Adhikari;Trupti V. Kotbagi;K. H. Shaughnessy;Ambar B. Shrestha;J. Sherwood;Y. Bao;M. Bakker
掺入金属纳米颗粒的分级多孔碳的合成可以通过“一锅”工艺进行，其中金属前体与聚合物前体和结构导向剂混合，进行溶胶-凝胶自组装聚合，然后在惰性气氛下热解。这种合成可能更便宜，并且可以使碳催化剂与有机溶剂更相容。之前的工作表明，添加金属盐会干扰自组装过程。为了防止这种干扰并提高热稳定性，使用环己基萨伦镍络合物作为金属前体。前体溶液的动态光散射 (DLS) 显示在不添加复合物的情况下存在胶束。观察到复合物的添加产生大的附聚物并且胶束浓度降低。形成的碳的 SEM 显示镍颗粒具有较宽的粒径分布和不均匀的空间分布。添加镍络合物后气体吸附仅显示出适度的变化。 XRD 证实了镍纳米颗粒的形成。在 SEM 中观察到的纳米颗粒的不均匀分布与在 DLS 中观察到的大团聚体一致，即环己基-salen 镍复合物，其未完全分散在聚合物中，因此在所得碳中产生不均匀分散。与其他萨伦配合物相比，碳的金属分散性和稳定性得到了改善。发现所得催化剂对于硼氢化钠还原对硝基苯酚具有催化活性，其催化活性与粒度分布一致。
Synthesis of hierarchically porous carbons incorporating metal nanoparticles can be carried out by a “one-pot” process in which the metal precursor is mixed with polymer precursors and structure directing agents, that undergoes a sol-gel self-assembly polymerization and then pyrolyzed under an inert atmosphere. Such syntheses are potentially cheaper and could make carbon catalysts more compatible with organic solvents. Previous work had shown that addition of metal salts interfered with the self-assembly process. To prevent this interference, and increase thermal stability, a nickel cyclohexyl salen complex was used as metal precursor. Dynamic light scattering (DLS) of the precursor solutions shows the presence of micelles in the absence of added complex. Addition of the complex is observed to give large agglomerates and a reduction in micelle concentration. SEM of the carbons formed shows that the nickel particles have a wide distribution of particle sizes and a heterogenous spatial distribution. Gas adsorption showed only modest changes resulting from nickel complex addition. XRD confirms the formation of nickel nanoparticles. The heterogenous distribution of nanoparticles observed in SEM is consistent with the large agglomerates observed in DLS being nickel cyclohexyl-salen complex which is not fully dispersed in the polymer and therefore gives heterogenous dispersion in the resulting carbon. The metal dispersion and stability of the carbon were improved over that observed with other salen complexes. The resulting catalysts were found to be catalytically active for the reduction ofp-nitrophenol by sodium borohydride with catalytic activity consistent with the particle size distributions.