Invisible Bactericidal Coatings on Generic Surfaces through a Convenient Hand

Robust antimicrobial coatings featuring high trans-parency, strong bactericidal activity, and an easy application procedure on generic surfaces can be widely accepted by the public to prevent pandemics. In this work, we demonstrated the hand-sprayer-based approach to deposit complex oxide coatings composed of Co-Mn-Cu-Zn-Ag on screen protectors of smartphones through acidic redox-assisted deposition (ARD). The as-obtained coatings possess high transparency (99.74% transmittance at 550 nm) and long-lasting durability against swiping (for 135 days of average use) or wet cleaning (for a routine of 3 times/day for 33 days). The spray coating enabling 3.14% Escherichia coli viability can further be reduced to 0.21% through a consistent elemental composition achieved via the immersion method. The high intake of Cu2+ in the coating is majorly responsible for the bactericidal activity, and the presence of Ag+ and Zn2+ is necessary to achieve almost complete eradication. The success of extending the bactericidal coatings on other typical hand-touched surfaces (e.g., stainless steel railings, rubber handrails, and plastic switches) in public areas has been demonstrated.