Cobalt ferrite–polyaniline heteroarchitecture: a magnetically recyclable photocatalyst with highly enhanced performances
Cobalt ferrite–polyaniline heteroarchitecture: a magnetically recyclable photocatalyst with highly enhanced performances
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DOI：
10.1039/c2jm31522j
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发表时间：
2012-08
影响因子：
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通讯作者：
P. Xiong;Qun Chen;Mingyang He;Xiaoqiang Sun;Xin Wang
中科院分区：
文献类型：
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作者：
P. Xiong;Qun Chen;Mingyang He;Xiaoqiang Sun;Xin Wang
采用原位氧化聚合法成功制备了铁酸钴-聚苯胺光催化剂。该复合材料在一定程度上保持了CoFe 2 O 4的优良磁性，因此光催化剂可以通过外磁场容易地分离。在阴离子染料和中性染料的情况下可以观察到显著的吸附，因为这些染料的带负电荷的基团或富电子基团与聚苯胺（PANI）的带正电荷的主链发生化学相互作用。这种吸附有助于促进染料的光降解。有趣的是，虽然单独的CoFe 2 O 4是一种非活性的可见光驱动的光催化剂，CoFe 2 O 4纳米粒子与聚苯胺的组合导致高的可见光照射下的染料降解的光催化活性。光活性的显著增强可归因于PANI中的激发态电子可迁移到CoFe 2 O 4的导带（CB），而CoFe 2 O 4的价带（VB）中的光生空穴可直接转移到PANI的HOMO，有效地防止了电子和空穴的直接复合。由于静电排斥，含有带正电荷基团的阳离子染料不能容易地进入PANI的带正电荷的主链，从而产生非常低的光降解速率。
A cobalt ferrite–polyaniline photocatalyst is successfully prepared by in situ oxidative polymerization. The excellent magnetic properties of CoFe2O4 are maintained in the composite to some extent, and therefore the photocatalyst can be separated easily by an external magnetic field. A significant adsorption can be observed in the case of the anionic dyes and neutral dyes because the negatively charged groups or the electron-rich groups of these dyes undergo chemical interactions with the positively charged backbone of polyaniline (PANI). Such an adsorption helps in promoting the photodegradation of the dyes. It is interesting that although CoFe2O4 alone is an inactive visible-light-driven photocatalyst, the combination of CoFe2O4 nanoparticles with PANI leads to high photocatalytic activity for the degradation of the dyes under visible light irradiation. The dramatic enhancement in photoactivity can be attributed to the excited state electrons in PANI which can migrate to the conduction band (CB) of CoFe2O4, and the photogenerated holes in the valence band (VB) of CoFe2O4 which can directly transfer to the HOMO of PANI, effectively preventing a direct recombination of electrons and holes. Due to electrostatic repulsion, the cationic dyes containing positively charged groups cannot easily gain access to the positively charged backbone of PANI, giving very low photodegradation rates.