Copper-graphene nanoflakes composite coating deposited by suspension plasma spray for antibacterial applications

The recent COVID-19 pandemic has highlighted the need for antiviral and antibacterial coatings as a basic option, along with disinfectants, to protect people from contamination. The surfaces we touch in our daily routine can potentially carry pathogens and thus contribute to the rapid spread of disease from one person to another. Copper (Cu) is one of the materials known for both its antiviral and antibacterial ability and its use dates back hundreds of years. Recently, studies have shown that the combination of graphene with copper coating improves its efficiency and antibacterial behaviour. In this work, we used a suspension plasma spraying technology to deposit a coating of Cu and graphene nanoflakes (GNFs) on metallic substrates. This technique guarantees a good dispersion of the GNFs in the Cu matrix and allows to have a nanometric/micrometric thickness of the coating, thus reducing the material consumption. The Cu-GNFs coating and the quality of the GNFs were characterized using scanning electron microscopy, Raman spectroscopy and X-ray diffraction. The antibacterial performance of the coating with Escherichia coli was studied and the results show that Cu-GNFs coating has a better antibacterial rate than copper (Cu) coating and exhibits a 99% reduction of Escherichia coli within 1h.