Introduction The gyroscope operation relies on the electrostatic actuation and capacitance detection between the resonator and the planar electrode, with a typical gap ranging from 20–150 µm. When organic impurities adhere to planar electrode’s surface, gap’s capacitance changes, leading to fluctuations in the excitation detection signal and thereby affecting the accuracy and reliability of the gyroscope. TiO2 thin film can effectively degrade organic pollutants through photocatalytic reactions. However, little research on its application on the surface of high-precision devices has been reported yet. The thickness of the TiO2 thin film affects the generation and effective separation of photo-generated electron-hole pairs, thereby influencing the photocatalytic performance of the TiO2 thin film. It is thus necessary to determine the thickness of the TiO2 thin film on the surface of the planar electrode through experiments. In this paper, a TiO2/Au composite thin film was designed to reduce the adsorption of organic substances on the surface of planar electrode and improve the thin film quality on the planar electrode surface. Methods TiO2 thin films with different thicknesses were prepared on fused quartz substrates via radio frequency magnetron sputtering. The films were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM), UV–visible spectrophotometry (UV–Vis), and photocatalytic reaction analysis. The crystalline structure, grain size, surface morphology, and optical absorption characteristics of the TiO2 thin films were analyzed to assess their impacts on the photocatalytic performance. The optimal thickness of the TiO2 thin film suitable for the surface of the planar electrode was determined to be 240 nm. Finally, the planar electrode with a TiO2/Au composite thin film was fabricated. The surface film layer of the planar electrode was characterized by nanoindentation, nano-scratching, and photocatalytic reaction equipment. The exceptional performance of the TiO2-coated planar electrode in terms of adhesion, friction resistance, and photocatalytic self-cleaning properties was validated. The final step involved assembling the prepared flat electrode with a hemispherical resonator and using a capacitance meter to validate the superior performance of the TiO2/Au composite film structured planar electrode for reducing the impact of organic impurities on the gap capacitance between the resonator and the planar electrode. Results and discussion The XRD patterns show that the crystalline integrity and grain size of the film gradually increase as the thickness of TiO2 thin film increases. The SEM and AFM images reveal that the surface roughness increases with the enlargement of grains as the film thickness increases. Based on the analysis of the properties of the TiO2 thin film, TiO2 thin film with a thickness of 240 nm exhibits the smallest bandgap width and the optimal photocatalytic performance. For the mechanical properties of the surface film layer on the planar electrode, the abrasion resistance of the planar electrode coated with the TiO2 thin film is higher than that of the electrode uncoated with the thin film. Also, the adhesion between TiO2 thin film and Au film on the surface of the planar electrode is comparable to the adhesion between Au film on the surface of the uncoated planar electrode and the substrate. The planar electrode undergoes photocatalytic self-cleaning experiments, TiO2/Au composite film structured flat electrode can reduce the impact of organic impurities on the capacitance uniformity between the resonator and the flat electrode, thereby contributing to the enhanceed performance of the hemispherical resonant gyroscope. Conclusions The crystallinity, grain size, and surface roughness of the TiO2 thin film increased with increasing TiO2 film thickness. The TiO2 thin film with a thickness of 240 nm exhibited the smallest bandgap width and appropriate grain size, thus demonstrating the optimal photocatalytic activity. The experimental verification of mechanical, photocatalytic, and capacitive performance of planar electrodes coated with TiO2/Au composite films revealed that the adhesion of the TiO2 thin film on the planar electrode met practical application requirements. Leveraging the excellent hardness and elastic modulus of the TiO2 thin film significantly enhanced the abrasion resistance of the surface film layer on the planar electrode. Also, the efficiency of photocatalytic degradation of organic impurities on the planar electrodes coated with TiO2 thin films was 1.6 times higher than that of the electrodes uncoated with the thin film. For assembling the prepared flat electrode with a hemispherical resonator and conducting capacitance meter testing, the TiO2/Au composite film structured flat electrode could degrade organic impurities and reduce their impact on the gap capacitance between the resonator and the flat electrode under UV light exposure. It was evident that the TiO2/Au composite film could have a promising practical application in the fabrication of resonant gyroscope flat electrodes. © 2024 Chinese Ceramic Society. All rights reserved.
