Fabrication, Superhydrophobicity And Anti-biofouling Properties Of Silicon Nanowires/Diamond Film

In the field of anti-biofouling,superhydrophobic materials have superiority over previous toxic paints and novel enzyme,owing to the advantages in non-toxicity,non-pollution and stability.Especially,superhydrophobic materials have extremely low surface energy and rough morphology,on which water droplet maintains spherical.It can be inferred that marine microorganism is difficult to adhere to them though viscous secretion.One of the main processes to fabricate superhydrophobic surface is establishing ordered rough morphology followed by coating a layer of low surface energy materials.Silane and fluoropolymer,as two typical low surface energy materials,shows low strength.Rough morphology is always fabricated by the methods of electrical deposition and lithography.Electrical deposition shows low-cost but leads to the instable wettability.The method of lithography increases the accuracy of morphology but is complex and high-cost.To get a balance between the degree of order and cost,silicon nanowire arrays(SiNWs)fabricated by metal-assisted method are selected because of controllability of porosity and consistence length and orientation.Diamond film has low surface energy,high strength,non-toxic and chemical durability,which shows great potential in biofouling resistance.Thus,SiNWs coated with diamond film are selected to fabricate superhydrophobic surface.Their wettability and anti-biofouling performance is systematically studied.The detailed content is as follows:(1)Monocrystal silicon wafers were etched into silicon nanowire arrays by solution containing HF and AgNO3.The effect of etching time on nanowire length,porosity and wettability were systematically studied by SEM and water contact angle(CA).It’s found that SiNWs are superhydrophilic,and that the value of CA of short arrays with small holes is higher than that of long arrays.These short-length nanowires were destroyed in a massive scale after immersion in the chlorella culture medium.(2)SiNWs were modified by the H2 plasma in MWCVD.Chemical terminal before and after plasma treatment was analyzed by XPS.The modified morphology and adhesion amount of chlorella on the treated SiNWs and as-prepared ones were analyzed by optical and SEM images.It is concluded that H2 plasma can etch the nanowires but the effect is limited.The improvement of hydophobicity and decrease of adhesion amount result from the increase of H terminal on the surface.(3)The gas of CH4 mixed with H2 is used to deposit carbon materials on Si nanowires.The phase structure of the carbon film was studied by Raman spectra and TEM.The morphology after plasma treatment and immersion in culture medium was studied by optical,fluorescent and SEM images.Based on consideration of CA and surface energy calculation,it’s found that diamond has lower surface energy than graphite.SiNWs coated with diamond under the parameters of 30 mbar gas pressure and 3%CH4 shows the CA of 156.7°.There are just a few chlorella cells on the superhydrophobic surface.The presence of diamond improves the hydrophobicity,which can be applied in anti-fouling area.