光催化係屬於高級氧化程序中的一環,常見的光觸媒材料為TiO2、ZnO、CdS、WO3、SnO2及Fe2O3等,以TiO2與ZnO最為廣泛研究。由於光觸媒材料應用上最大的困難為光觸媒的固定化技術,利用熔膠凝膠法、濺鍍法或燒鍍法較難製備大面積的塗層。本研究係利用電漿與高速火焰熔射技術,分別將ZnO、TiO2、ZnO/3wt%Al2O3及ZnO/50wt%TiO2奈米結構材料噴覆於AISI304不繡鋼基板表面,針對氧化鋅/氧化鈦及其複合粉末利用UV光(352nm)降解亞甲基藍水溶液之光催化特性進行研究。研究結果顯示熔射後塗層表面形貌多為奈米結構,熔射ZnO/3wt%Al2O3之塗層其表面形貌多為奈米片狀(nano disk)氧化鋅,熔射過程發現添加氧化鋁能有效提高氧化鋅塗層堆疊效率;X射線繞射(XRD)分析顯示熔射ZnO/3wt%Al2O3之塗層其特徵峰向右偏移,表示鋁可能有摻雜進氧化鋅結構,高速火焰熔射ZnO/50wt%TiO2塗層其相態多為ZnO 與TiO2之複合相(Zn2Ti3O8及Zn2TiO4),電漿熔射塗層除了複合相外,增加了Ti8O15缺氧相,純TiO2塗層因熔射高溫其Anatase相大都轉變為Rutile相。光催化特性顯示,經UV光照24小時,能將亞甲基藍水溶液降解為透明水溶液,高速火焰熔射TiO2塗層光照12小時降解率為100%,而電漿熔射ZnO/3wt%Al2O3塗層降解效率最差為45%。綜合分析結果顯示,塗層表面結構與光觸媒材料影響光催化降解率,進行降解亞甲基藍水溶液,TiO2塗層較ZnO塗層效率佳,添加氧化鋁於氧化鋅粉末中,能增強熔射時堆疊效率,但經電漿熔射後其光催化效率降低,塗層中產生TiO2缺氧相會因氧空缺形成電子電洞再結合中心,導致其光催化效率較差,高速火焰熔射塗層均較電漿熔射塗層之光催化效果佳。
Among the many photocatalysts, such as TiO2, ZnO, CdS, and WO3, TiO2 and ZnO are known to be the best photocatalyst in terms of its chemical stability. In this study, Nano ZnO, TiO2, ZnO/3wt%Al2O3, and ZnO/50wt%TiO2 photocatalytic coating were deposited on stainless steel 304 by thermal spraying process(APS and HVOF). The photocatalytic properties was evaluated by using methylene blue(MB) aqueous soiution by UV light(352nm). The results showed that the microstructure of ZnO/3wt%Al2O3 coating were nano disk, thermal sprayed powder filled Al2O3 can improve deposition rate; XRD results indicate that phase of TiO2 coating was transformed of anatase to rutile. The phase of HVOF ZnO/50wt%TiO2 coating formed compound phase (Zn2Ti3O8 and Zn2TiO4) and APS ZnO/50wt%TiO2 coating formed Ti8O15. When the HVOF TiO2 coating by UV-illuminated 12 hours, degenerate rate was 98% and APS ZnO/3wt%Al2O3 coating was 46%. The photocatalytic properties of TiO2 coating were higher than others coating (ZnO coating, ZnO/50wt%TiO2 coating and ZnO/3wt%Al2O3 coating). HVOF coating were higher than APS coating.