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Tuning the wettability and photocatalytic efficiency of heterostructure ZnO-SnO2 composite films with annealing temperature
摘要： ZnO-SnO2 composite films were spin-coated and annealed at different temperatures. The characteristics of the films were studied by using XRD, FESEM, AFM, FT-IR and UV–Vis spectroscopy. The wetting nature of the films was assessed by observing the water contact angle by sessile drop method. It was seen that the annealing temperature had a significant role in increasing the surface roughness. This leads to a change in water contact angles which are consistent with the Wenzel state of wetting. Photodegradation of model pollutants in liquid phase (cationic methylene blue, anionic methyl orange) and solid phase (octadecanoic acid) was performed to measure the photocatalytic efficiency of the films. The enhanced photocatalytic efficiency of films annealed at higher temperatures is due to better crystallinity and formation of heterostructure that inhibits the re-combination of charge entities (electron-hole).
关键词： Roughness,Contact angles,Heterostructures,Photocatalysis
更新于2025-11-19 16:56:35
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Omnidirectional light harvesting enhancement of dye-sensitized solar cells decorated with two-dimensional ZnO nanoflowers
摘要： Surface hydrophilicity has a crucial effect on adhesion forces in air. However, the influence demands clarification. A spherical tip was used to measure adhesion forces on silicon samples with different treatment methods on an atomic force microscope at high relative humidity. The treatment methods were plasma treatment with storage for a time and ultrasonic cleaning in alcohol and water. Both abnormally large and small adhesion forces were observed, and the adhesion force behavior is closely related to surface hydrophilicity. With plasma treatment, the maximum force can be as large as ~4.8 μN, which was attributed to the formation of siloxane bonds (Si-O-Si) between opposing surfaces and the capillary force due to a water bridge. However, the abnormally large adhesion force can only last for a few hours, and then either decreases gradually or decreases suddenly to an abnormally small value. The decrease was attributed to the displacement of hydroxyl groups by organic molecules and the adsorption of some other airborne contaminants on the surface. The possible reasons for abnormally small forces were also presented. However, the abnormal values were not observed on samples with ultrasonic cleaning. These results may help facilitate the anti-adhesion design for silicon-based small-scale systems.
关键词： pull-off force,water bridge,contact angles,Atomic force microscopy,adhesion by chemical bonding
更新于2025-09-12 10:27:22
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Vacuum-UV of polyetheretherketone (PEEK) as a surface pre-treatment for structural adhesive bonding
摘要： Polyetheretherketone (PEEK) is known for its poor wettability and poor adhesive properties. Hence, for the creation of reliable high-strength structural adhesive bonded joints, surface treatment of PEEK is required. In this work high strength bondable PEEK surfaces were achieved through a vacuum-UV (VUV) treatment. Samples of amorphous and semi-crystalline PEEK films were exposed to different VUV radiation doses. Additionally oxygen low-pressure plasma (LPP) and untreated (as received) PEEK samples were investigated for comparison. Surfaces were characterized using x-ray photoelectron spectroscopy (XPS), contact angle measurements (CA), atomic force microscopy (AFM) and confocal laser scanning microscopy (CLSM). Tensile tests of the PEEK films were carried out, to investigate changes in the mechanical properties in the bulk of the PEEK films due to the VUV exposure. The adhesive bond strength of treated specimen was determined through two different test methods (tensile and shear). These strengths were compared to the created surface properties. A strong correlation between the contact angle and the creation of functional groups was observed. VUV radiation appears as a suitable pre-treatment method for PEEK, as adhesive bonds of high strength were achieved after 5 seconds. Additionally, the usage of a VUV excimer lamp is simple, cheap and easy for automation.
关键词： X-ray photoelectron spectroscopy,Vacuum-UV (VUV),contact angles,chemical surface functionalization,structural adhesive bonding,Polyetheretherketone (PEEK),atomic force microscopy
更新于2025-09-11 14:12:44