Thickness-dependent photocatalytic performance and wettability of barium-doped ZnO thin films synthesized via SILAR technique

The Successive Ionic Layer Adsorption and Reaction (SILAR) technique is a versatile method for depositing thin films with controlled thickness surfaces. However, achieving high-quality thin films with an optimal number of deposition cycles required to improve film properties applicable in photocatalysis is an important consideration. In this study, we investigate the influence of the number of cycles (3, 6, 9, 12, and 15 cycles) in the SILAR technique on the characteristic parameters, including the structural, morphological, and optical properties of deposited Ba/ZnO thin films on glass substrates. X-ray diffraction analysis reveals the hexagonal polycrystalline nature of Ba-doped ZnO films. The intensity of peaks increased with increasing of cycles number which the preferred orientation was (002), while the crystallite size decreasing from 11.105 to 10.904 nm. SEM shows grain size increasing from 29.71 to 44.79 nm as SILAR growth cycles rise from 3 to 15. The thin films' transmittance measurements ranged from 290 to 1200 nm. The thin films' energy band gaps decreased from 3.68 to 3.25. Additionally, the wettability of Ba-doped ZnO films increased with the number of SILAR cycles, rising from 21.23° at 3 cycles to 56.55° at 15 cycles. Furthermore, the photocatalytic performance of samples under visible sunlight was studied for methylene blue and amoxicillin at different cycle numbers. At 15 cycles, the degradation of methylene blue reached 93.51%, whereas amoxicillin was degraded by 54.31%. This study offers valuable insights into the influence of Ba-doped ZnO thin films with varying cycles on the quality of thin films, which is an applicable facility in photocatalytic degradation.

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