Enhancement of self-cleaning properties and durability of super-hydrophobic carbon nitride nanostructures by post-annealing treatment
Document Type
Article
Publication Date
3-15-2021
Abstract
In the present work, the effects of annealing temperatures (TA) on the wetting behaviour of carbon nitride (CNx) nanostructures were studied based on static and dynamic contact angle measurements. The contact angle (C-A) was exponentially increased from 102.8 +/- 1.5 degrees for the as-deposited film to super-hydrophobic behaviour of 158.1 +/- 1.5 degrees as T-A was increased to 700 degrees C. The contact angle hysteresis (CAH) of the films was examined by tilted the samples at an angle of about 45 degrees or until the droplet can be detected by an optical camera; and their advancing and receding angles were measured. The acquired result shows that the applied T-A to the CNx nanostructures enhances the water repellence of the surfaces. The calculated CAH indicates that as-deposited film demonstrates ``sticky'' state with higher hysteresis (>55 degrees) compared than film annealed at 700 degrees C which shows ``slippy'' state with CAH <5 degrees. The difference in the CAH values was believed to have resulted from the different wetting regimes of both films especially their surface morphology, surface roughness, and its porosity. The durability of the CNx nanostructures was tested by water dropped for 11 times. From the results, film annealed at T-A of 700 degrees C shows excellent durability performance by still maintaining its super-hydrophobic behaviour after water was dropped for more than 10 times. The surface morphology and chemical bonding present in the film seems not much different compared to the first time water was dropped. This indicates that high annealing temperature might remove the defects of the nanostructure, furthermore strengthen it thus, exhibited good water repellences and self-cleaning properties as well as high reusability of the nanostructures.
Keywords
Self-cleaning, Hydrophobicity, Contact angle hysteresis, Durability
Divisions
PHYSICS
Funders
Universiti Malaya Research Grant (UMRG) -AFR (Frontier Science) (RG391-17AFR)
Publication Title
Surface and Coatings Technology
Volume
409
Publisher
Elsevier
Publisher Location
PO BOX 564, 1001 LAUSANNE, SWITZERLAND