Ti/TiO2-Sb-SbOx multifunctional sensors were obtained by plasma electrolytic oxidation in the anodic–cathodic mode. The resulting films contain TiO2 and up to 5 at.

Electrodes of the composition Ti/TiO2,SbOx were obtained by single-stage plasma electrolytic oxidation in aqueous electrolytes with antimony hydroxocomplexes. The surface morphology and composition of TiO2,SbOx layers deposited on titanium were studied by scanning electron microscopy, X-ray diffraction analysis, and X-ray photoelectron spectroscopy. The obtained layers contain anatase TiO2 and up to 1 at % of antimony as Sb2O3 and Sb2O5. The resulting Ti/TiO2,SbOx electrodes were tested as pH sensors. They have close to Nernst electrode function in the pH range from 2 to 10 (53 ± 1 mV/pH). In the acid–base titration of strong (HCl) and weak (CH3COOH) acids with Ti/TiO2,SbOx electrodes, potential jumps are obtained that are not inferior in magnitude to the potential jump for a glass electrode. A possibility of using Ti/TiO2,SbOx electrodes to determine the alkalinity of technogenic waters is shown.

Изучены состав, морфология поверхности, рН- и фосфатная функции фосфорсодержащих оксидных пленок на титане, сформированных методом плазменно-электролитического оксидирования в электролитах, содержащих от 0,05 до 0,2 моль/л дигидрофосфата калия. Все сформированные оксидные слои имеют в своем составе диоксид титана в модификации анатаз и 7-8 ат.% фосфора. Выявлена рН-функция сформированных пленок в интервале рН от 2 до 7 и ее усиление в результате гидроксилирования поверхности электродов в щелочных буферных растворах. Полученные оксидные пленки на титане проявляют определенную фосфатную функцию и могут быть использованы в качестве сенсоров в осадительном потенциометрическом титровании, в частности, для контроля качества воды природных водных объектов и сточных вод на содержание фосфатов и других кислых примесей. The composition, surface morphology, pH- and phosphate functions of phosphorus-containing oxide films on titanium formed by plasma-electrolytic oxidation in electrolytes containing from 0.05 to 0.2 mol/l of potassium dihydrophosphate have been studied. All the oxide layers incorporate titanium dioxide in the anatase crystal form and 7-8 at.% of phosphorus. The pH function of the formed films in the pH range from 2 to 7 and its amplification are revealed resulting from hydroxylation of the electrode surface in alkaline buffer solutions. The obtained oxide films on titanium exhibit a specific phosphate function and can be used as sensors in precipitation potentiometric titration, in particular, for water quality control of natural water bodies and waste water including determination of the content of phosphates and other acidic impurities.

This paper describes the photoelectrochemical properties of titanium oxide formed by plasma electrolytic oxidation. The possibility of correlation between the photoactivity of the formed systems and their impedance characteristics was investigated. Equivalent circuitries which allow explanation of the character of the impedance spectra were constructed and interpreted. The role of heat treatment and surface modification with platinum on the photoelectrochemical and electrochemical characteristics of the formed systems was demonstrated.

The behavior of metal-oxide electrodes formed using the method of plasma electrolytic oxidation in a tetraborate electrolyte and additionally modified by platinum at acid-base and precipitation potentiometric titration has been investigated. The possibility of application of the fabricated electrodes in analysis of man-made waste waters on the example of potentiometric determination of alkalinity and chlorides content has been demonstrated. The advantages of the fabricated metal-oxide systems related to their polyfunctional character and the possibility to determine two hydrochemistry parameters using a single electrode have been shown. Key words: metal-oxide electrodes, plasma electrolytic oxidation, potentiometry, hydrochemistry parameters (Russian) DOI: http://dx.doi.org/10.15826/analitika.2013.17.3.003 G.I. Marinina, A.S. Lapina, M.S. Vasilyeva, O.D. Arefyeva, and N.B. Kondrikov School of Natural Sciences, Far East Federal University, Vladivostok, Russia

Polyfunctional properties of a ruthenium-titanium oxide electrode in the absence of polarization and the possibility of its application to the potentiometric detection of iron(III) titration with an ethylenediaminetetraacetic acid solution, acid-base and redox reaction types have been demonstrated. Mechanisms of reactions determining the potentials of electrodes of this type have been investigated by a number of methods.