Provided is an antimicrobial photoreactive composition comprising a photocatalytic multijunction composite that is photoreactive in ordinary room lighting and comprises at least one photocatalytic heterojunction that is primarily carbon based. The composition further comprises at least one surface-coupling material, optionally at least one additive selected from a charge-transfer augmenting material, a light-capturing augmenting material, an antimicrobial augmenting material(s), or a combination thereof, and a carrier. The composition can be coupled to a surface or embedded in a cationic polymer matrix to form an antimicrobial film that is removable. Further provided is a method of disinfecting a surface comprising applying the antimicrobial photoreactive composition to a surface.