Preparation,Characterization And Properties Of Transitional Metal-based Inorganic Superhydrophobic Materials

Superhydrophobicity plays an important role in both fundamental research and industrial applications on account of their unique wetting behavior and promising applications especially for self-cleaning,no loss liquid transfer and the analysis of small-volume liquid sample.Although enormous studies of superhydrophobic surfaces have been reported in recent years,most of these superhydrophobic surfaces usually involve organic compounds.Those superhydrophobic surfaces were usually obtained via two approaches:chemically modifying the hydrophilic surfaces with organic compounds that have low surface free energy;or roughness construction by surface patterning on polymer-based materials.However,such surface modifications are not suitable for harsh environment applications.Because the organic compounds used in surface modification will be gradually decomposed chemically and thermally,and surface patterns will be destroyed mechanically.Thus,the practical applications of polymeric and other superhydrophobicmaterials with anorganic modification layer are limited by their own physical and chemical properties,such as little durability and poor thermally stability.In addition,most fabrication processes of these superhydrophobic materialsare complicated,expensive and refered to harsh chemical modification conditions,which also hamper their applications.Compared with organic materials,inorganic metal oxides possess better durability.However,the superhydrophobicity of some metal oxides,such as pure ZnO,TiO₂,SnO₂ and V₂O₅,eventually become superhydrophilic after UV exposure.High water adhesion is yet another important property describing the interaction of a liquid droplet with surfaces.However,to the best of our knowledge,superhydrophobic surface of metal oxides with high adhesion to water without surface modification has rarely reported.Therefore,it remains of essential significance and great challenge to prepare a new superhydrophobic material with long-term durability and high water adhesion.Owing to the above disadvantage,the main focus of this study is to provide simple and economical approach for the construction of inorganic superhydrophobic surface with high water adhesion and long-term durability suitable for different conditions especially harsh environments,which could greatly advance the practical applications of sticky superhydrophobic material.Meanwhile,controlled synthesis and properties are also investigated.For exploring to resolve the aforementional issume,we dividethe dissertation into some parts:A novel type of highly stable and sticky superhydrophobic cerium dioxide?CeO₂?nanotube material was prepared by the hydrothermal treatment without any chemical modification for the first time.Water droplet on the material surface shows a static water contact angle?CA?about 157°but the water droplet is pinned on the material surface even when the material surface is turned upside-down.The maximum water adhesive value is 20?L.And the high water adhesion was explained by acombined effect of the negative pressures generated by the volume change of sealed air,hydroxyl groups on the surface of CeO₂nanotubes and the van der Waals'attraction at solid-liquid interface.Importantly,the superhydrophobic CeO₂ nanotube material shows remarkable thermal stability even at temperatures as high as 450°C,long-term durability in chemical environment including strong acid,strong alkali and other special corrosive liquids as well as air-storage.Finally,the potential application in no-loss water transportation of this sticky superhydrophobic CeO₂material was demonstrated.A novel semiconductor oxide material with both durable superhydrophobicity and photocatalytic depollution was reported for the first time.Interestingly,this CeO₂ nanotube material displays a durable superhydrophobicity ever under 365 and 254 nm UV light irradiation,but shows UV-induced enhanced adhesion to water with prolonging irradiation time.Importantly,this change in water adhesion can be reversed by heating treatment to restore the original adhesive value of 20?L.Further,the maximum volume of the water droplet adhered on the material surface of CeO₂ nanotubes can be regulated without loss of superhydrophobicity during the heating treatment/UV irradiation cycling.Meanwhile,the synthesized CeO₂ nanotubes show excellent photocatalytic activity.And the superhydrophobic character can recover after polluted with oily contaminants,due to the photocatalysis of CeO₂ nanotubes.The UV-resistant superhydrophobicity with high water adhesion is distinctly different from other metal oxide semiconductors such as ZnO,V₂O₅,TiO₂ and SnO₂.This is due to pure ZnO,V₂O₅,TiO₂ and SnO₂,eventually become superhydrophilic after UV exposure.Twin-like hydroxide samarium nanorods were synthesized by a simple and low-cost hydrothermal treatment of SmCO₃?OH?as precursor with sodium hydroxide.This is a first example for the synthesis of hydroxide samarium by hydroxide carbonate as raw material.Importantly,these hydroxide samarium nanorods do not require surface hydrophobic modification to achieve superhydrophobicity and have high adhesion to water droplets.Water droplet on the surface of the twin-like hydroxide samarium nanorod film shows a static water contact angle about 153°but the nearly spherical water droplet is immobilized on the material surface even when the surface of the twin-like hydroxide samarium nanorod film is turned upside-down.The maximum water adhesive value reaches 48?L.The effects of alkali concentration and reaction time on the phase structures and morphologies of hydroxide samarium nanorods were investigated.Furthermore,this superhydrophobic hydroxide samarium nanorods show good superhydrophobic stability under UV exposure and long-term air-storage.In addition,this superhydrophobic hydroxide samarium nanorods show excellent photocatalytic activity toward the degradation of methylene blue under UV light irradiation.This represents a first example to demonstrate the photocatalytic ability of hydroxide samarium nanorods as photocatalyst.In this work,we developed a facile and cost-effective method for direct fabrication of copper nanoparticles to engender superhydrophobicity for nickel foam.The superhydrophobic surface was prepared by a simple chemical reduction of copper acetate and hydrazinehydrate at room temperature.By altering the initial copper ion concentration,superhydrophobic surfaces without any modification of low-surface-energy materials were obtained.The surface morphological studies demonstrate that the as-prepared surfaces are rough and display superhydrophobic character on wetting due to generation of air pockets?The Cassie-Baxter state?.Because of the low adhesion of water droplets on the as-prepared surfaces,the surfaces exhibite superhydrophobic and superoleophilic properties simultaneously with a water contact angle of about 160.5o,a water sliding angle of about 5°and an oil contact angle of about 0°.Superhydrophobic copper nanoparticle coated nickel foam uniquely withstands saturated sodium chloride,mild alkali,acids and displays long-term durability in both water-immersion and air-storage at room temperature?25°C?.Furthermore,as-prepared surface can effectively separate oil-water mixtures through an ordinary filtering process.