Iron-based metal–organic frameworks fabricated by microwave irradiation: a nanoplatform for the controlled delivery of nutrients

• Microwave-assisted synthesis strategy for fabricating Fe-based metal–organic frameworks. • Loading of target nutrients through a nanoplatform with enhanced space-time yields. • Tunable nutrient release profiles for matching requirements of crops Metal-organic frameworks (MOFs) are promising candidates for controlled-release fertilizers (CRFs), yet their widespread application has been constrained by the time-consuming, energy-intensive nature of conventional hydrothermal synthesis, which is largely limited to Fe-based structures. To address these limitations, we developed a rapid microwave-assisted strategy for synthesizing multi-nutrient MOFs fertilizers. Systematic parameter analysis identified modulator dosage as the primary factor governing Fe-MOFs formation, followed by reaction temperature, whereas reaction time and microwave power exhibited comparatively minor effects. These parameters concomitantly dictated nutrient-release kinetics. The optimized synthesis conditions comprised a urea-to-phosphate molar ratio of 0.5–1 (MW1/2), a reaction time of 1.25–2.5 h (MW4/2; 8–16 times faster than hydrothermal synthesis), a temperature of 120–140 °C (MW6/2), and a microwave power of 600–800 W (MW8/2). With a 6.58‑fold higher space-time yield (STY) and an 84.8% lower specific energy consumption (SEC) compared to hydrothermal method (HY), MW2 demonstrates strong potential for pilot‑scale industrial production. Subsequent incorporation of Zn (MW10), Ca (MW11), or a Zn/Ca mixture (MW12) modulated the coordination environment of the Fe-MOFs framework, with Fe-centered coordination remaining dominant; MW11 and MW12 displayed the most pronounced structural and morphological alterations. The multi-metallic MOFs achieved a 2.1-fold enhancement in cumulative nutrient release compared to the single-metal MW2, with MW12 exhibiting the fastest release profile. All systems followed diffusion-erosion release kinetics. Pot experiments confirmed significant agronomic benefits, increasing biomass by 13.8% in pak choi and 25.8% in rice seedlings, with MW12 performing most effectively. Collectively, this microwave-assisted approach establishes an efficient and scalable route to advanced, multi-nutrient MOFs-based CRFs with tunable nutrient-delivery properties.