Solid state field-assisted silver ion exchange in porcelain stoneware: A new route toward antimicrobial tiles?

The development of tiles possessing antimicrobial activity is of great technological and scientific interest to improve the functionality of a very widely used article. Also the current SARS-CoV-2 pandemic is drawing the attention towards materials or compounds able to inactivate the virus, silver being among all the most promising one. In the present work, field-assisted ion exchange process was used to functionalize porcelain stoneware by introducing silver into the material surface using a solid silver electrode. The application of a small direct electric current (10 mA cm−2) at 380 °C allowed to fasten silver diffusion. The penetration of silver into stoneware appears homogeneous and primarily involves an exchange between silver and sodium ions under the effect of the external electric current. Penetration depths approaching 120 μm can be obtained in only 5 min. Preliminary characterization revealed that the Ag-exchanged stoneware possesses a strong biocidal action against Staphylococcus aureus.