Electroless Ag nanoparticle deposition on TiO2 nanorod arrays, enhancing photocatalytic and antibacterial properties.

Hypothesis: The small size of the nanoparticles used to obtain high surface area photocatalysts makes their removal from solution difficult. Producing photocatalysts on substrates would alleviate this limitation. Adding heterojunctions to photocatalysts, for example, TiO₂/Ag, could improve photocatalytic performance due to Schottky junction formation and introduce antibacterial properties.

Experiments: TiO₂ nanorod arrays were synthesised on a substrate via a hydrothermal approach, on which Ag nanoparticles were deposited using an electroless plating technique with varied deposition times and metal precursor concentrations. Photocatalytic performance was evaluated by monitoring Rhodamine B (RhB) degradation under ultraviolet light and antibacterial properties of the films tested using Methicillin-resistant Staphylococcus aureus.

Findings: The Ag nanoparticle content was controlled by the Ag deposition process. The TiO₂/Ag nanorod array containing 6.6 atomic% Ag as nanoparticles of ∼ 25 nm in diameter degraded 88 % of the RhB in 6 h compared to 54 % degradation for bare TiO₂ nanorods under the same reaction conditions. Decreased photoluminescence with heterojunction formation would indicate electron transfer from the TiO₂ into the Ag nanoparticles, thereby reducing charge carrier recombination. The antibacterial test conducted in the dark revealed enhanced performance for the TiO₂/Ag sample compared to TiO₂ nanorods against Methicillin-resistant Staphylococcus aureus after 16 h exposure with a death rate of 84 %.