Songnan Zhang

Robust fluorine-free superhydrophobic PDMS–ormosil@fabrics for highly effective self-cleaning and efficient oil–water separation

Superhydrophobic cotton fabrics were prepared via a facile and environmentally friendly strategy to deposit an organically modified silica aerogel (ormosil) thin film onto the fabrics first, followed by polydimethylsiloxane (PDMS) topcoating. The PDMS–ormosil coating displayed a uniform 3D fractal-like structure with numerous loose micro-scale pores, while the PDMS layer increased the binding strength of the hierarchical ormosil film to form a highly robust porous network on the fibers. In comparison with hydrophilic cotton fabrics, the modified cotton fabric exhibited a highly superhydrophobic activity with a water contact angle higher than 160° and a sliding angle lower than 10°. The as-constructed PDMS–ormosil@fabrics are able to withstand 100 cycles of abrasion and 5 cycles of accelerated machine wash without an apparent decrease of superhydrophobicity. In addition, the superhydrophobic cotton fabrics are very stable in strongly acidic and alkaline solutions. Furthermore, the superhydrophobic coating has no or negligible adverse effect on the important textile physical properties of the cotton fabric, such as the strength, air permeability, and flexibility. The composite super-antiwetting fabrics have demonstrated excellent anti-fouling, self-cleaning ability and are highly efficient in oil–water separation for various oil–water mixtures. This facile synthesis technique has the advantages of scalable fabrication of multifunctional fabrics for potential applications in self-cleaning and versatile water–oil separation.

One‐dimensional TiO2 Nanotube Photocatalysts for Solar Water Splitting

Hydrogen production from water splitting by photo/photoelectron‐catalytic process is a promising route to solve both fossil fuel depletion and environmental pollution at the same time. Titanium dioxide (TiO2) nanotubes have attracted much interest due to their large specific surface area and highly ordered structure, which has led to promising potential applications in photocatalytic degradation, photoreduction of CO2, water splitting, supercapacitors, dye‐sensitized solar cells, lithium‐ion batteries and biomedical devices. Nanotubes can be fabricated via facile hydrothermal method, solvothermal method, template technique and electrochemical anodic oxidation. In this report, we provide a comprehensive review on recent progress of the synthesis and modification of TiO2 nanotubes to be used for photo/photoelectro‐catalytic water splitting. The future development of TiO2 nanotubes is also discussed.

Bioinspired Special Wettability Surfaces: From Fundamental Research to Water Harvesting Applications.

Nowadays, the pollution of water has become worse in many parts of the world, which causes a severe shortage of clean water and attracts widespread attention worldwide. Bioinspired from nature, i.e. spider silk, cactus, Namib desert beetle, Nepenthes alata, special wettability surfaces have attracted great interest from fundamental research to water-harvesting applications. Here, recently published literature about creatures possessing water-harvesting ability are reviewed, with a focus on the corresponding water-harvesting mechanisms of creatures in dry or arid regions, consisting of the theory of wetting and transporting. Then a detailed account of the innovative fabrication technologies and bionic water-harvesting materials with special wetting are summarized, i.e. bio-inspired artificial spider silk, bio-inspired artificial cactus-like structures, and bio-inspired artificial Namib desert beetle-like surfaces. Special attentions are paid to the discussion of the advantages and disadvantages of the technologies, as well as factors that affect the amount of water-harvesting. Finally, conclusions, future outlooks and the current challenges for future development of the water-harvesting technology are presented and discussed.

Synthesis, modification, and photo/photoelectrocatalytic degradation applications of TiO2 nanotube arrays: a review

Abstract Titanium dioxide nanotube arrays (TiO2 NTAs) have attracted much interest due to their unique highly ordered array structure, outstanding properties, and potential applications in photo/photoelectrocatalytic degradation of pollutants, hydrogen production, supercapacitors, dye-sensitized solar cells, sensors, and biomedical devices. It has been fabricated via a facile electrochemical anodic oxidation of Ti substrate in fluoride-containing electrolytes. Combined with our previous work, we comprehensively review the recent progress of TiO2 TNAs on the synthesis processes, forming mechanism, and modification used to improve the photoelectric properties. In addition, this article summarizes some of the recent advances on the photo/photoelectrocatalytic degradation of pollutants. Besides, other applications and the future development of TiO2 TNAs are also briefly discussed and addressed.

Understanding the Role of Dynamic Wettability for Condensate Microdrop Self-Propelling Based on Designed Superhydrophobic TiO2 Nanostructures.

The ability to release the adhered drops on superhydrophobic surfaces is very important for self-cleaning, antifrosting/icing, microfluidic device, and heat transfer applications. In this paper, three types of in situ electrochemical anodizing TiO2 nanostructure films are rationally designed and fabricated on titanium substrates with special superwettability, viz., TiO2 nanotube arrays, irregular TiO2 nanotube arrays, and hierarchical TiO2 particle arrays (HTPA), and their corresponding behavior in condensate microdrop self-propelling (CMDSP) is investigated. Compared to the flat titanium counterpart, all three types of rough TiO2 samples demonstrate a uniform distribution of smaller microscale droplets. Among the treated surfaces, the HTPA possesses the highest condensate density, and more than 80% of the droplets possess a diameter below 10 μm. Theoretical analysis indicates that the feature is mainly due to the morphology and structure induced extremely low droplet adhesion on super-antiwetting TiO2 hierarchical surfaces, where the excess surface energy released from the migration leads to the self-propelling of merged microdrop. This work offers a way to rationally construct CMDSP surfaces with excellent self-cleaning, antifrosting/icing ability, and enhanced condensation heat transfer efficiency.

Bioinspired Surfaces with Superwettability for Anti-Icing and Ice-Phobic Application: Concept, Mechanism, and Design

Ice accumulation poses a series of severe issues in daily life. Inspired by the nature, superwettability surfaces have attracted great interests from fundamental research to anti-icing and ice-phobic applications. Here, recently published literature about the mechanism of ice prevention is reviewed, with a focus on the anti-icing and ice-phobic mechanisms, encompassing the behavior of condensate microdrops on the surface, wetting, ice nucleation, and freezing. Then, a detailed account of the innovative fabrication and fundamental research of anti-icing materials with special wettability is summarized with a focus on recent progresses including low-surface energy coatings and liquid-infused layered coatings. Finally, special attention is paid to a discussion about advantages and disadvantages of the technologies, as well as factors that affect the anti-icing and ice-phobic efficiency. Outlooks and the challenges for future development of the anti-icing and ice-phobic technology are presented and discussed.