Axial suspension plasma sprayed Ag-TiO2 coating for enhanced photocatalytic and antimicrobial properties

Abstract

Ag-TiO2 coating has been extensively studied for its antimicrobial and photocatalytic applications. In this study, we developed a straightforward and efficient method with use of Axial Suspension Plasma Spray (ASPS) to deposit Ag-TiO2 coatings. In ASPS, a suspension containing AgNO3 solution and TiO2 particles (pure anatase) was prepared and plasma sprayed on SS304 stainless steel substrate to form the Ag-TiO2 coating. The microstructure, photocatalytic activity, and antibacterial property against E-coli (CFT073 and C1214) and Methicillin-resistant Staphylococcus aureus (MSRA, USA300) of the deposited coating were characterized. Results showed the deposited Ag-TiO2 is a composite coating consisting of anatase, rutile and Ag nanoparticles. The introduction of a small amount of Ag (up to 0.2at% of Ag/Ti in the coating) exhibited a significant increase in photocatalytic activity, achieving a rate at least twice as fast as that of the TiO2 coating without Ag in the methyl orange degradation test. Moreover, these Ag-TiO2 coatings demonstrated remarkable antimicrobial activity, completely inactivating E. coli CFT073, effectively inhibiting the growth of E. coli C1214 by four orders of magnitude and MRSA by nearly three orders of magnitude. The employment of ASPS, in conjunction with AgNO3 solution, presents a simple and effective approach for the production of nano Ag particles in a composite coating. This technique has great potential in surface modification on medical devices for anti-infective purpose.