Unraveling the Effects\nof Strain-Induced Defect Engineering\non the Visible-Light-Driven Photodynamic Performance of Zn<sub>2</sub>SnO<sub>4</sub> Nanoparticles Modified by Larger Barium Cations

Waterborne infections caused by pathogenic microorganisms\nrepresent\nserious health risks for humans. Ternary zinc–tin oxide nanoparticles\nhave great potential as a cost-effective, environmentally friendly,\nand efficient candidate for waterborne infections; however, their\nphotocatalytic and antibacterial effects are quite limited due to\ninsufficient visible light absorption and rapid electron–hole\nrecombination. Herein, barium-doped zinc stannate (Ba@ZTO) nanoparticles\nwere synthesized by the hydrothermal method and used for the first\ntime not only as antibacterial agents to prevent the spread of the\nharmful bacteria <i>S. aureus</i> and <i>E. coli</i> but also as photocatalysts to degrade the organic pollutant rhodamine\nB. Unexpectedly, Ba<sup>2+</sup> ions exhibited compressive stress\nbehavior instead of the predicted tensile stress when inserted into\nthe ZTO crystal lattice, playing an active role in increasing oxygen\nvacancies within the crystal lattice and in the formation of hydroxyl\nradicals in the bulk solution and hydrogen peroxide (H<sub>2</sub>O<sub>2</sub>) radicals, significantly improving the photocatalytic\nand antibacterial properties. Strain-induced defects created by the\ninsertion of larger barium ions into the ZTO lattice promote the increase\nof shallow traps for boosting photocatalytic/disinfection properties\nwhile suppressing deep-level traps that encourage nonradiative recombination.\nIn essence, defect and strain engineering opens a promising route\nto achieve high disinfection efficiency by inducing larger cation\nions under visible light in oxide-based materials.