还原剂对多孔阳极氧化铝纳米孔道结构的影响

Influence of Reducer on the Nanopore Structure of Porous Anodic Alumina

多孔阳极氧化铝(PAA)和多孔阳极氧化钛纳米管(PATNT)的结构调控近年来倍受关注.在形成机理尚不清楚的情况下,对PAA和PATNT的结构调控很难避免盲目性.为验证"氧气气泡模具"可以形成纳米孔道这个新观点,本文采用化学方法对PAA的结构进行调控,成功地引入了一种还原剂来吸收纳米孔道中的氧气气泡.在添加还原剂的草酸溶液中得到了一种特殊的阳极氧化铝膜.研究了还原剂的含量对磷酸溶液中形成PAA孔道结构的影响,结果表明随着还原剂含量的增加,PAA的孔道直径逐渐减小,有序性降低.对比了添加还原剂前后阳极氧化过程的电压-时间曲线的差异,结果表明,在含有还原剂溶液中制备的阳极氧化铝膜的导电性明显提高.在密封的条件下,还原剂能吸收掉孔道中的氧气,使气泡模具效应消失,得到完全的致密型氧化膜.这些实验事实充分证明PAA中有序孔道的形成是氧气气泡模具效应的结果.

In recent years, attention has been focused on adjustment and control of the nanostructures of porous anodic alumina （PAA） and porous anodic TiO2 nanotubes （PATNT）. Because the formation mechanism of PAA and PATNT is still unclear, it is difficult to adjust the nanostructures of PAA and PATNT. To validate the novel viewpoint of the nanopore resulting from an oxygen bubble mold, an innovative chemical approach was used to adjust the PAA nanostructures. One successful approach is to use a reducer to absorb the oxygen bubbles in the nanopores. A novel anodic alumina film was obtained in a mixed solution of the reducer and oxalic acid. The influence of the reducer on the PAA nanostructures which formed in H3PO4 solution was investigated in detail. The experimental results showed that the regularity and the diameters of the nanopores in the PAA decreased as the reducer content increased. The differences in the voltage-time curves between electrolytes with and without the reducer were analyzed quantitatively. The results showed that the conductivity of the anodic oxide film that formed in the electrolyte with the reducer was better than that in the electrolyte without the reducer. When aluminum anodizes in a sealed case, oxygen bubbles are easily absorbed by the reducer, the oxygen bubble mold effect disappears, and a compact alumina film is obtained. Overall, these results clearly demonstrate that nanopores result from the oxygen bubble mold effect.