3W,5W,10W uv laser

UV laser-ablated Cu superwetting surface with improved anti-icing and antibacterial properties

Jun 09 , 2023

UV laser-ablated Cu superwetting surface with improved anti-icing and antibacterial properties


Ultraviolet laser-ablated technique was used to improve the anti-icing and antibacterial properties of copper (Cu) with the objective of achieving efficient heat exchange performance. The laser scanning space interval exhibited a critical influence on the surface topography. SEM observation showed that nano-villi-like products appeared on the surface, which resulted in the formation of a micro/nano-hierarchical structure when the scanning interval was below 40 µm. When the scanning space interval was above 40 µm, the surface presented only a micron-level papilla/groove pattern without any nano-villi-like product. Combined analysis of XRD, TEM, and XPS results indicated that the nano-villi products were partially crystallized copper oxide particles with 5–10 nm size. It was speculated that nano-oxide was obtained by vapor deposition of Cu caused by laser ablation. Furthermore, after modification with FAS-17, the hydrophobicity of the nano-villi-like surface became significantly higher than that of the papilla/groove surface. The highest water contact angle reached 156.30 ± 0.53° and the water sliding angle was as low as 1.57 ± 0.99°. In the anti-icing test at − 10 °C, the delayed freezing time of this superhydrophobic surface reached 9923 s. This excellent anti-icing property can be attributed to the improvement in critical activation energy for ice nucleation and reduction in interfacial thermal conductivity caused by superhydrophobic surface. Finally, the inhibition zone test proved that laser ablation could significantly improve the antibacterial activity of Cu against E. coli and S. aureus.

Graphical Abstract





Copper (Cu) heat exchangers are often used as condensers because of their good heat transfer coefficient and excellent antibacterial property. However, the hydrophilicity of Cu makes it easy to form condensate water from humid air, and even frost or freeze when these exchangers are operated in cold area. The water or ice in heat exchanger provides apt environment to breed bacteria and contaminate the incoming air [1], [2], [3]. This requires significant research efforts on improving the aspects of both anti-icing and antibacterial performance of these condensers.

Superhydrophobic materials refer to materials with both a water contact angle (WCA) greater than 150° and a water sliding angle (WSA) less than 10° [4]. This type of material can trap a layer of air between water droplets and its surface to expand the thermodynamic barrier of icing [5], [6], [7]. Consequently, superhydrophobic surfaces play a key role in preventing the ice nucleation and delaying the freezing of the droplet, thus it exhibits a good anti-icing/frost performance [8], [9], [10]. Till date, many techniques such as hydrothermal synthesis [11], [12], [13], laser ablation [14], [15], [16], [17], electrochemical deposition [18], [19], [20], anodic oxidation [21], [22], [23], and other methods have been used to fabricate superhydrophobic surfaces with a certain degree of icing retardation [24]. In particular, some superhydrophobic surfaces with micro/nano-hierarchical structures presented a strong anti-icing ability [11], [25], [26].

Although the superhydrophobic surface can resist the adhesion of most bacteria [27], studies have shown that the superhydrophobic surface is more likely to breed bacteria than the smooth surface when the bacteria is too small or the surface hydrophobicity decreases [28], [29]. Thus, it is speculated that the preparation of a superhydrophobic surface using antibacterial materials can significantly improve the antibacterial performance of the superhydrophobic surface [30]. Cu ions can not only interact with the cell wall to inhibit or destroy the membrane structure of the cell [31], [32], but also enter the bacterial cell to reduce the protein or enzyme activity, and thus it can ultimately denature protein and destroy DNA molecule [33], [34]. Importantly, the superhydrophobic surface prepared with Cu or its compounds exhibits good antibacterial properties. For example, Cu deposited on the surface of the veneer [35] and zirconium [36] exhibits superhydrophobic properties and the significant reduction in in vitro bacterial adhesion activity.

However, Cu nanoparticles (NPs) are unstable in open air, as a result, they are rarely used in practical applications. As a visible-light-sensitive p-type semiconductor material [37], copper oxide can produce free radicals with a sterilization ability when exposed to sunlight, thus actually it shows better antibacterial properties than Cu [38], [39], [40], [41]. For instance, Subhadarshini et al. [42]used electrochemical deposition method to prepare Cu2O nanopetals on Cu foil, and this surface showed excellent superhydrophobic property and better antibacterial property than raw Cu foil. Mahmoodi et al. [43] used a thermal oxidation method to produce CuO nanowires (NWs) in situ on a Cu foil, which exhibited better antibacterial activity than untreated Cu foil.

Laser ablation technique offers the advantages such as high efficiency and low pollution, and it is suitable for large-scale manufacturing. Laser ablation can produce surface texture on Cu substrate and then convert the surface into a superhydrophobic state by surface modification [44], [45]. In this study, aiming at improving the antibacterial and anti-icing performance of Cu, an ultraviolet (UV) laser was used to construct a rough surface microstructure and simultaneously deposit nano copper oxides on the surface to prepare micro-Cu/nano-oxides hierarchical surface structure. Chemical modification was used to reduce the solid surface tension and prepare a superhydrophobic surface. This study provides new insight into laser ablation of metals for the anti-icing as well as antibacterial application.


Section snippets


Cu foil with a purity of 99.9% and a thickness of 0.05 mm was used as the raw material. Square samples with sizes 10 mm and circular samples with diameter 10 mm were used for anti-icing and antibacterial tests, respectively. Before laser ablation, samples were polished in sequence using 320#, 600#, 1200#, 1500#, and 2000# SiC sandpaper, and then cleaned successively in deionized water, ethanol, and acetone by ultrasonic cleaning for 20 min

Laser ablation

Surface texture was formed by laser ablation. A UV laser 

SEM analysis

By changing the two sets of parameters during laser ablation processing, different micro–nano hierarchical structures were obtained as shown in Fig. 2, Fig. 3. Fig. 2 shows SEM images of surface morphologies of the samples with different scanning intervals and the constant 10 times of laser ablation processing were used in this set. Laser scanning interval was found to have a significant impact on the surface morphology of the Cu foil. Overall view in Fig. 2(a1)–(e1) exhibits that the surface


In this study, ultraviolet laser-ablated technique combined with chemical surface modification was used to adjust the wettability of the copper (Cu) foil surface, which resulted in successful improvement of its anti-icing and antibacterial properties. The results showed that the laser scanning interval played a crucial role in the surface topography. When the interval was ≤ 40 µm, nano-villi-like Cu oxides were generated on the surface of Cu foil. Analysis of XRD, TEM, and XPS studies indicates 

CRediT authorship contribution statement

Jiang-hao Qiao: Conceptualization, Supervision, Project administration, Funding acquisition, Writing – review & editing, Funding acquisition. Song-jiang Li: Resources, Investigation, Formal analysis, Data Curation, Visualization, Writing - Original Draft. Li-ping Kong: Conceptualization, Supervision, Investigation Project administration. Yan-cai Liu: Resources, Investigation. Yu-zheng Huang: Resources, Investigation, Formal analysis. Kun Chen: Resources, Investigation. Yu-chen Li: Resources,

Declaration of Competing Interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.


This work was financially supported by Basic Research Program of Xuzhou (Grant No. KC21015), National Natural Science Foundation of China (Grant No. 52175204 and 51875563) and the Fundamental Research Funds for the Central Universities (Grant No. 2014QNA13).

Special thanks to the Analysis and Testing Center of China University of Mining and Technology for their help in the experiment.

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