Fabricating effective heterojunction in metal-organic framework-derived self-cleanable and dark/visible-light dual mode antimicrobial CuO/AgX (X = Cl, Br, or I) nanocomposites

• A new synthetic strategy to obtain intimately dispersed heterojunction is presented. • Silver halide-loaded Cu-BTC was calcined to yield CuO/AgX nanocomposites. • A high degree of amorphization of silver halide in the CuO matrix was observed. • The nanocomposites showed enhanced visible-light photocatalytic activity than CuO. • Antimicrobial studies revealed dark/light dual-mode activity of the nanocomposites. Owing to the alarming consequences of antimicrobial resistance, the requirements for effective antimicrobial materials working under dark and visible-light conditions are on the high rise. On a different note, heterojunctions between semiconductors are highly desirable to enhance the photocatalytic activity of the individual components in a synergistic way. In this work, we address these two aspects in a single material composition through a rationally designed synthetic strategy. Among several candidates, silver and copper are known to exhibit high antimicrobial characteristics in the dark. Besides, CuO and silver halides are known for their visible-light photocatalytic activity. Hence, a copper-based porous metal organic framework, Cu-BTC, has been deposited with a silver halide followed by calcination to yield CuO/AgX (X = Cl, Br, or I) nanocomposites. The initial deposition of the silver halide over the MOF is envisaged to provide a high dispersion of the halide in the CuO matrix through numerous anchoring pods and thereby result in a tight and effective heterojunction. The nanocomposites obtained through this approach have been characterized structurally and morphologically using various techniques. The nanocomposites have been studied for their visible-light photocatalytic and self-cleaning ability via photodegradation of methylene blue and 4-chlorophenol as model systems. Further, their antimicrobial efficacy has been studied against E. coli and S. aureus both under dark and visible-light conditions. In addition to revealing the high potential of the CuO/AgX nanocomposites towards environmental applications, the synthetic approach presented herein can potentially be extrapolated to fabricate exotic compositions possessing enhanced efficacy.