Solution Method for NiO/TiO₂–SiO₂–NiO Spherical Layered Structures Obtaining

Abstract— Layered spheres of composition NiO/TiO₂–SiO₂–NiO have been synthesized, and their physicochemical, optical, and structural characteristics have been studied. These spheres consist of an inner nickel oxide layer and an outer TiO₂–SiO₂–NiO coating. The developed method allows to achieve a uniform distribution of elements and to enhance the interaction between the inner and outer layers. This increases the stability of the structure during heat treatment at the phase formation stage. Thermal analysis indicates that temperature significantly affects phase formation in TiO₂–SiO₂–NiO films. The temperature treatment mode that preserves the spherical shape of the material and facilitates the formation of nickel oxide and titanium dioxide in anatase modification has been selected: 100°C for 30 min, 200°C for 30 min, 300°C for 30 min, 350°C for 30 min, and 500°C for 1 h. This enables the achievement of optimal crystallization and adhesion between the layers. The nickel oxide incorporation into the TiO₂–SiO₂–NiO composition modifies the optical properties of titanium dioxide, reducing its band gap energy to 2.47 eV. This reduction enables visible light absorption, significantly enhancing photocatalytic potential. The synthesized NiO/TiO₂–SiO₂–NiO layered structures exhibit significant potential for environmental applications, including water and air purification, water splitting processes, and the degradation of organic pollutants under visible light.