P123-PMMA dual-templating generation and unique physicochemical properties of three-dimensionally ordered macroporous iron oxides with nanovoids in the crystalline walls.
P123-PMMA dual-templating generation and unique physicochemical properties of three-dimensionally ordered macroporous iron oxides with nanovoids in the crystalline walls.
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DOI：
10.1021/ic1023604
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发表时间：
2011-02
影响因子：
4.6
通讯作者：
Ruzhen Zhang;H. Dai;Yucheng Du;Lei Zhang;Jiguang Deng;Yunsheng Xia;Zhenxuan Zhao;Xue Meng
中科院分区：
文献类型：
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作者：
Ruzhen Zhang;H. Dai;Yucheng Du;Lei Zhang;Jiguang Deng;Yunsheng Xia;Zhenxuan Zhao;Xue Meng
以硝酸铁为金属前驱体，在乙醇或乙二醇和甲醇的混合溶液中，采用双模板法[Pluronic P123和聚甲基丙烯酸甲酯（PMMA）胶体微球]，经550 °C煅烧后，制备了菱形晶化大孔壁中含有纳米孔洞的三维有序大孔氧化铁（3DOM）.讨论了这种结构材料的可能形成机理。采用XRD、TGA/DSC、FT-IR、BET、HRSEM、HRTEM/SAED、UV-vis、XPS、H（2）-TPR等手段对材料的物化性能进行了表征。以甲苯氧化为探针反应考察了材料的催化性能。结果表明，在不添加P123的条件下，制备的α-Fe（2）O（3）为3DOM结构，大孔壁中没有纳米孔洞;而双模板法制备的α-Fe（2）O（3）具有高质量的3DOM结构，多晶大孔壁中存在纳米孔洞，比表面积较高（32-46 m2/g）.表面活性剂P123在3DOM结构的铁氧化物的壁内的纳米空隙的产生中起关键作用。有多价铁离子和吸附的氧物种的存在下，每个样品的表面上，与三价铁离子和氧吸附物种的浓度是不同的样品样品。双模板法制备的氧化铁样品比本体法制备的样品具有更好的低温还原性。同时存在的3DOM结构的骨架和大孔壁中的纳米空隙引起了铁氧化物的带隙能量的下降。高的氧吸附量、较大的比表面积、较好的低温还原性和独特的含纳米孔洞的3DOM结构是氧化铁材料在甲苯氧化反应中表现出优异催化性能的原因。
Three-dimensionally (3D) ordered macroporous (3DOM) iron oxides with nanovoids in the rhombohedrally crystallized macroporous walls were fabricated by adopting the dual-templating [Pluronic P123 and poly(methyl methacrylate) (PMMA) colloidal microspheres] strategy with ferric nitrate as the metal precursor in an ethanol or ethylene glycol and methanol mixed solution and after calcination at 550 °C. The possible formation mechanisms of such architectured materials were discussed. The physicochemical properties of the materials were characterized by means of techniques such as XRD, TGA/DSC, FT-IR, BET, HRSEM, HRTEM/SAED, UV-vis, XPS, and H(2)-TPR. The catalytic properties of the materials were also examined using toluene oxidation as a probe reaction. It is shown that 3DOM-structured α-Fe(2)O(3) without nanovoids in the macroporous walls was formed in the absence of P123 during the fabrication process, whereas the dual-templating strategy gave rise to α-Fe(2)O(3) materials that possessed high-quality 3DOM structures with the presence of nanovoids in the polycrystalline macropore walls and higher surface areas (32-46 m(2)/g). The surfactant P123 played a key role in the generation of nanovoids within the walls of the 3DOM-architectured iron oxides. There was the presence of multivalent iron ions and adsorbed oxygen species on the surface of each sample, with the trivalent iron ion and oxygen adspecies concentrations being different from sample to sample. The dual-templating fabricated iron oxide samples exhibited much better low-temperature reducibility than the bulk counterpart. The copresence of a 3DOM-structured skeleton and nanovoids in the macropore walls gave rise to a drop in the band-gap energy of iron oxide. The higher oxygen adspecies amounts, larger surface areas, better low-temperature reducibility, and unique nanovoid-containing 3DOM structures of the iron oxide materials accounted for their excellent catalytic performance in the oxidation of toluene.