Co-, W-, and P-containing oxide heterostructures on titanium substrates have been obtained by plasma electrolytic oxidation at current densities of 0.1 and 0.15 A/cm². The heterostructures have been studied by the X-ray diffraction, scanning electron microscopy, and X-ray photoelectron spectroscopy. Conglomerates of nanoparticles with an elemental composition corresponding to CoWO₄, CoO, and Co₃(PO₄)₂ have been found on the surface of the samples. Air-annealing of samples at 700°C for 1 h leads to the transformation of nanoparticles into nanocrystals with CoWO₄ and Co₃(PO₄)₂ phases. The annealed samples and the initial samples obtained at 0.15 A/cm² are also contain the crystalline phase of TiO₂. All samples are characterized by a small bandgap: E_g values for the direct (n=2) and indirect (n=1/2) transitions are equal 2.77 and 2.07 eV, respectively, for both initial samples. All samples exhibit photocatalytic activity in indigo carmine (IC) degradation at pH=2.9 under solar light illumination. The proposed mechanism of solar light-driven photocatalytic activity of Ti/TiO₂-CoWO₄-Co₃(PO₄)₂ structures includes the formation of p-n heterojunction between TiO₂ and CoWO₄, capture of holes by Co₃(PO₄)₂, and producing a high-valence cobalt ions Co³⁺/Co⁴⁺, which could further induce oxidation reactions with water molecules and IC.

通过等离子体电解氧化在0.1和0.15A / cm ^2的电流密度下已经获得了钛基板上的含Co，W和P的氧化物异质结构。通过X射线衍射，扫描电子显微镜和X射线光电子能谱研究了异质结构。在样品表面上发现了具有与CoWO ₄，CoO和Co ₃（PO ₄）₂相对应的元素组成的纳米颗粒的团聚体。样品在700°C空气退火1小时会导致纳米颗粒转变为具有CoWO ₄和Co ₃（PO ₄）₂的纳米晶体阶段。在0.15A / cm ^2下获得的退火样品和初始样品也包含TiO ₂的结晶相。所有样本都具有一个小的带隙特征：两个初始样本的直接（n = 2）和间接（n = 1/2）跃迁的E _g值分别等于2.77和2.07 eV。在阳光照射下，所有样品在pH = 2.9的靛蓝胭脂红（IC）降解中均表现出光催化活性。提出的太阳光驱动的Ti / TiO ₂ -CoWO ₄ -Co ₃（PO ₄）₂结构光催化机理包括在TiO ₂和CoWO之间形成pn异质结。_{如图4所示}，通过Co ₃（PO ₄）₂捕获空穴，并产生高价钴离子Co ³⁺ / Co ⁴⁺，其可进一步引起与水分子和IC的氧化反应。