Unraveling\nthe Formation of Ternary AgCuSe\nCrystalline Nanophases and Their\nPotential as Antibacterial Agents

AgCuSe nanoparticles could contribute to the growth of\nstrongly\nlight-absorbing thin films and solids with fast ion mobility, among\nother potential properties. Nevertheless, few methods have been developed\nso far for the synthesis of AgCuSe nanoparticles, and those reported\ndeliver nanostructures with relatively large sizes and broad size\nand shape distributions. In this work, a colloidal cation exchange\nmethod is established for the easy synthesis of AgCuSe NPs with ca.\n8 nm diameters and narrow size dispersion. Notably, in this lower\nsize range the conucleation and growth of two stoichiometric ternary\ncompounds are generally observed, namely the well-known <i>eucairite</i> AgCuSe compound and the novel <i>fischesserite</i>-like\nAg<sub>3</sub>CuSe<sub>2</sub> phase, the latter being less thermodynamically\nstable as predicted computationally and assessed experimentally. An\noptimal range of Cu/Ag precursor molar ratio has been identified to\nensure the growth of ternary nanoparticles and, more specifically,\nthat of the metastable Ag<sub>3</sub>CuSe<sub>2</sub> nanophase isolated\nfor the first occasion. The attained size range for the material paves\nthe way for utilizing AgCuSe nanoparticles in new ways within the\nfield of biomedicine: the results obtained here confirm the antibacterial\nactivity of the new Ag<sub><i>x</i></sub>Cu<sub><i>y</i></sub>Se<sub><i>z</i></sub> nanoparticles against\nGram-positive bacteria, with significantly low values of the minimal\ninhibitory concentration.