ИСТИНА

Porous anodic aluminum oxide (PAАO) is a nanostructured material with a high specific surface area, varying from units to tens of square meters per gram of substance. An interesting and practically important task is to create an optical sensor platform based on PAАO. To solve this problem, it is necessary to strictly control the chemical composition of the samples, the type of defects and their concentration. Two series of the PAАO were synthesized by the anodic oxidation method in solutions based on selenium and sulfuric acid with different synthesis parameters (electrolyte concentration, current density, temperature, anodization time). Selenium and sulfur were found in the composition of the corresponding PAАO. It was found that all samples have an amorphous structure, but for the first time it was found that when the synthesis temperature of the samples is increased only to 40 °C and at a current density of 15 mA/cm2, the samples begin to crystallize. We assume that this is due to the nanosized phase of aluminum oxide. In all PAAO samples, defects of the oxygen vacancy type were found, the concentration of which is approximately the same in both PAAO series and increases with the growth of the electrolyte temperature. This is confirmed by the data of X-ray phase analysis, according to which with the increase of the electrolyte temperature during synthesis, a decrease in the oxygen content in the PAAO is observed. It should be noted that only in the PAAO based on selenic acid were defects of the oxygen anion-radical type detected, and in a concentration more than an order of magnitude higher than oxygen vacancies. A mechanism for the observed effect is proposed that takes into account the higher oxidizing capacity of selenic acid. The obtained data can be used to obtain an optical sensor platform based on PAАO with specified characteristics.