Synergistic antimicrobial activity of Ti₃C₂–Ag₃PO₄ heterostructures via visible-light, ROS-mediated mechanism

The rapid emergence of antimicrobial resistance has intensified the search for multifunctional nanomaterials capable of delivering efficient microbial inactivation through well-defined physicochemical mechanisms. In this work, a Ti₃C₂ MXene–silver phosphate (Ag₃PO₄) heterostructure was successfully fabricated by a facile in-situ growth strategy, enabling the homogeneous deposition of Ag₃PO₄ nanoparticles on conductive Ti₃C₂ nanosheets. X-ray diffraction analysis confirmed the formation of highly crystalline cubic Ag₃PO 4 , while the characteristic (00 l) and (110) diffraction peaks of Ti₃C₂ remained intact, demonstrating that the MXene framework was preserved during composite formation without detectable impurity phases. FTIR spectroscopy verified the presence of phosphate groups through the characteristic P–O stretching and O–P–O bending vibrations. The optical properties investigated by UV–Vis diffuse reflectance spectroscopy revealed strong absorption throughout the visible region with a band gap of approximately 2.3–2.5 eV, whereas the broad absorption tail originating from Ti₃C₂ enhanced visible-light harvesting and facilitated charge transport. TEM and HRTEM analyses demonstrated uniformly distributed Ag₃PO₄ nanoparticles intimately anchored onto ultrathin Ti₃C₂ sheets, forming a well-defined heterointerface with distinct lattice fringes corresponding to both components. SAED patterns confirmed the polycrystalline nature of Ag₃PO₄ and the absence of metallic Ag or TiO₂ secondary phases. The Ti₃C₂–Ag₃PO₄ composite exhibited concentration-dependent antimicrobial activity against Candida albicans and Aspergillus spp., producing inhibition zones of 20 and 13 mm, respectively. Reactive oxygen species investigations revealed the generation of hydroxyl radicals, superoxide radicals, hydrogen peroxide, and singlet oxygen, which collectively disrupted microbial membranes and induced cell death. The enhanced antimicrobial performance is attributed to the synergistic interaction between conductive Ti₃C₂ and photoactive Ag₃PO₄, where efficient interfacial charge separation suppresses electron–hole recombination and promotes reactive oxygen species generation under visible-light irradiation. These findings establish Ti₃C₂–Ag₃PO₄ as a promising visible-light-responsive antimicrobial material for biomedical coatings, environmental disinfection, and water-treatment applications.