Short-chain ligand-assisted coprecipitation for scalable and green synthesis of monodisperse inorganic nanocrystals: opportunities, mechanisms, and challenges

Monodisperse inorganic nanocrystals are pivotal in catalysis, optoelectronics, energy conversion and storage, and biomedicine, yet an ideal synthesis method that simultaneously satisfies room-temperature operation, green chemistry, ultrafast kinetics, low cost, and large-scale feasibility still remains challenging. This review critically benchmarks solution-phase methods for monodisperse inorganic nanocrystals, including hydrothermal/solvothermal synthesis, hot-injection and heat-up routes, two-phase liquid–liquid synthesis, conventional long-chain ligand-assisted coprecipitation, and short-chain ligand-assisted coprecipitation (SCLAC). In this review, we first summarize the principles, advantages, and limitations of conventional methods, then discuss the formation mechanism of monodisperse nanoparticles, with emphasis on the distinction between classical LaMer-type burst nucleation and non-classical or ligand-mediated nucleation/growth pathways. We then evaluate SCLAC as a promising candidate for green and scalable synthesis. SCLAC uses short-chain fatty acid and aliphatic amine ligands in ethanol/water under ambient conditions and has enabled sub-5 nm rare-earth-doped oxide and fluoride nanocrystals with high photoluminescence quantum yields and batch scales up to the kilogram level. However, its greenness, cost, mechanism, and generality across other material classes require further quantitative validation. We conclude by outlining a roadmap for extending SCLAC to metal sulfides, noble metals, multicomponent systems, and continuous-flow manufacturing, while clearly distinguishing experimentally demonstrated advantages from proposed mechanisms and future opportunities.