Hydrophilic Ligand‐Assisted Synthesis of Water‐Dispersible Transition Metal Sulfide Nanoparticles

ABSTRACT Transition metal sulfide nanoparticles (TMS NPs) hold promise for optoelectronic and biomedical applications. However, their synthesis often faces challenges in achieving water dispersibility and precise size control under mild conditions. Herein, we present a one‐pot hydrophilic ligand‐assisted synthesis strategy integrating bifunctional ligands with metal‐anchoring and hydrophilic groups into the NP coordination sites during nucleation. This enables the ultrafast five‐minute synthesis of monodispersed CuS NPs. This integration creates a flexible coordination shield that prevents aggregation to achieve surface hydrophilicity. Using CuS as a model, we utilize coordination stability constants as theoretical descriptors alongside the regulation of metal‐to‐sulfur ratios, reaction time and temperature to precisely modulate NP properties. This rational design yields NPs with a strong photothermal conversion efficiency of 53.1% for advanced imaging and antibacterial purposes. Moreover, the colloid stability of CuS NPs can be effectively preserved for over six months, thanks to the ligand‐metal charge transfer interactions, highlighting their superior long‐term storage capability. Furthermore, this strategy can be successfully extended to the synthesis of other TMS NPs, thereby providing a generalizable approach for designing functional TMS nanomaterials with enhanced surface hydrophilicity and tunable size for biomedical applications.