Multifunctional Modulation of High‐Performance Zn _x Fe _{3− x} O ₄ Nanoparticles by Precisely Tuning the Zinc Doping Content

Abstract The possibility to precisely control important properties of nanoparticles (NPs) such as their size, morphology, surface charge, or doping content is crucial for enhancing the performance of existing solutions beyond the state‐of‐the‐art and for enabling novel applications. In this work, custom‐tailored Zn x Fe 3− x O 4 NPs are synthesized at different Zn doping concentrations to augment and expand their usefulness for high‐performance applications in nanomedicine. By precisely increasing the Zn 2+ content in the range of 0 ≤ x ≤ 2.0, the discussed NPs can sequentially acquire valuable properties enabling magnetic resonance imaging, near‐infrared (NIR) photothermal effects, NIR photocatalytic and photoelectric effects, depending on the variation of substitution position of the Zn 2+ in the magnetite structure and the emergence of a ZnO/ZnFe 2 O 4 heterostructure at high doping concentrations. The presented work demonstrates and explainsa facile route for the synthesis and modulation of multifunctional nanomaterials with manifold roles in disease diagnostics and therapy, and provides helpful guidance in designing divalent transition metal ion‐doped nanomaterials.