A Study On Preparation And Performance Of Titanium Implant Coatings With Photo-Induced Hydrophilicity And Photocatalytic Antibacterial Activity

TiO₂ is an ideal multifunctional coating materials for medical implant for its photoinduced hydrophilicity and photocatalytic antimicrobial activity.However,TiO₂ has a broad bandgap and high charge carrier recommendation rate,making it challenging to meet commercialization needs.In current studies,it has been shown that oxygen vacancies（OVs）can promote the separation of photogenerated carriers and enhance the spectral response range,but that the spatial distribution of OVs determines the effect.For photocatalysis,surface OVs are beneficial,as they can mitigate the surface recombination of charge carriers,but bulk OVs are deleterious to photocatalysis because they can serve as recombination centers for charge carriers.Since the OVs between（001）facets have a higher migration barrier than that of（101）facets,we have proposed an optimization design idea that uses（001）preferred orientation to regulate OVs,and fabricates the anatase-TiO₂ films with excellent photocatalytic activity using magnetron sputtering,heat treatment and ion bombardment.In this study,the influence of processing parameters and the effects of（001）preferred orientation and surface OVs concentration on the separation efficiency of photogenerated carriers in TiO₂ films have been systematically investigated.The specific research contents are as follows:（1）Study on preparation and properties of anatase-TiO₂（A-TiO₂）films.A-TiO₂ films are deposited by reactive magnetron sputtering with pure titanium target.The films have a dense and flat surface with columnar crystal structure.The XRD patterns show that all of the A-TiO₂films are in the anatase phase,but the crystallinity of the film（UHT）before heat treatment is weak.Crystallinity and surface roughness of the film（HT）are improved after heat treatment,and it displays higher photocatalytic activity than UHT.The methyl orange degradation rate of HT is 18.1%after 150 min of UV irradiation,which is 15.0%more than that of UHT.（2）Study on preparation and properties of A-TiO₂ films with（001）preferred orientation.During magnetron sputtering,the effect of Ar/O₂ flow ratio（90:10,95:5,98:2）on the crystal structure of TiO₂ films has been studied.The results show that the crystallinity of the films decreases with decreasing O₂ flow rate,while the OVs concentration increases.After heat treatment,the films（ht＿10,ht＿5,ht＿2）have a good anatase structure,but the exposure ratio of（001）facets varies.The percentage of exposed（001）facets of ht＿10,ht＿5 and ht＿2 are 13.0%,17.4%and 23.2%,respectively.Due to high percentage of exposed（001）facets can promote the separation of photogenerated carriers and provide more oxidation reaction sites,the ht＿2exhibits the highest photocatalytic performance,and its methyl orange degradation rate is as high as 21.3%after 150 min of UV irradiation;the contact angle can reduce from 66°to 18°after 40 min of UV irradiation;the sterilization rate of E.coli is 23.7%after 10 min of UV irradiation.（3）Study on OVs regulation of A-TiO₂（001）films and its properties.By using hydrogen plasma,we prepared OVs and investigated the effect of（001）preference orientation on surface OVs.Results indicate that ht＿2 with the highest（001）preference orientation has the highest surface OVS concentration and the best photocatalytic performance after plasma treatment.Within 150 min of being exposed to UV light,the degradation rate of methyl orange can reach35.4%.Due to abundant surface adsorbed hydroxyl groups can significantly improve the hydrophilicity stability,the water contact angle is still below 50°after natural aging for four days,and recovers from 46°to 11°after UV irradiation for 40 min;the sterilization rate of E.coli is as high as 49.1%after 10 min of UV irradiation.By combining（001）facets with the high surface OVs concentration in TiO₂,the photocatalytic performance of TiO₂ film is significantly improved,and the practical application of photoinduced hydrophilicity and photocatalytic sterilization of TiO₂ are supported.