Inspired by lotus leaves, superhydrophobic surfaces are defined as those with a water contact angle (WCA > 150°) and a sliding angle (SA < 10°) [1], [2], [3], [4], [5], [6], [7], [8], [9]. In recent years, superhydrophobic surfaces have attracted attention in various fields due to their anti-fouling [10], [11], drag reduction [12], anti-icing [13], [14], anti-frosting [15], self-cleaning [16], anti-corrosion [17], [18], and oil-water separation [19], [20] properties. The lotus leaf surface has numerous protrusions and waxy materials, which create an air layer between the lotus leaf and water droplets, preventing the water droplets from adhering to the lotus leaf surface. Therefore, the key to superhydrophobic materials is the presence of particles that provide roughness and low surface energy materials.

Generally speaking, substances that can increase surface roughness include inorganic particles such as TiO2 [21], [22], SiO2 [23], [24], BaSO4 [25], [26], and Al2O3 [27], [28], [29]. Currently, the low surface energy substances used in superhydrophobic materials are fluorides or silane compounds, which are harmful to the environment and expensive. Although significant progress has been made in the field of superhydrophobic surfaces in recent years, most studies still focus on the realization of a single or a few functions. It still faces severe challenges to simultaneously integrate highly efficient oil-water separation, strong antibacterial activity, significant photothermal effect and self-cleaning performance on a single cotton fabric substrate. This is because achieving multifunctionality and simultaneously constructing roughness is difficult.

Chitosan, as a natural polymer with abundant sources, is biodegradable and highly biodegradable. The abundant -OH and -NH2 on its molecular chain can be used as active sites for grafting hydrophobic long chains [30], [31], [32], [33]. Incorporating functional nanoparticles into chitosan can significantly enhance its antibacterial, photothermal and other properties. ZnO has excellent photocatalytic activity, ultraviolet shielding property and antibacterial performance. GO has excellent dispersion performance, outstanding thermal conductivity and electrical conductivity [34], [35]. This makes it an excellent material for preparing superhydrophobic coatings. Kong et al. [36]prepared a superhydrophobic coating with insulating properties by modifying nano ZnO with dodecanethiol, but the antibacterial properties of ZnO were not discussed. Li et al. [37] prepared a tough and hydrophobic coating by in-situ growth of nano‑zinc oxide, but the method was rather complicated.

In this study, chitosan was prepared by chemical methods, and GO-ZnO composite materials were synthesized by the hydrothermal method. Finally, the CS-ZnO-GO-ODA superhydrophobic coating was successfully synthesized through the Schiff Base reaction. The GO layer provides both photothermal conversion capability; the loaded ZnO nanowires significantly enhance the antibacterial performance, and together with GO, they form a micro-nano two-level rough structure, laying the foundation for superhydrophobicity. The WCA of the superhydrophobic cotton fabric obtained by the impregnation method was 160.4°. The coating was subjected to antibacterial experiments, and the results showed that the CS-ZnO-GO-ODA coating had an antibacterial rate of up to 95% against S aureus and E coli. In the de-icing test, the ice droplets on the surface of the superhydrophobic cotton fabric could melt and fall off quickly within 120 s. The separation efficiency of the superhydrophobic cotton fabric for various oil-water mixed substances was greater than 95%. In addition, the CS-GO-ZnO-ODA coating has excellent dye degradation performance, with a degradation efficiency of 82% for Congo red within 4 h. The CS-ZnO-GO-ODA superhydrophobic cotton fabric has broad application prospects in anti-icing, de-icing, oil-water separation, and self-cleaning.