An Atomic-Level Bimetallic MOF Platform Overcoming the Stability-Performance Tradeoff for Laser Propulsion

This work establishes a materials design paradigm that achieves simultaneous enhanced stability and performance for photon-based propulsion. We introduce an atomic-level bimetallic platform to overcome the inherent trade-off between high thrust efficiency and environmental stability, particularly against hydrolysis. This is achieved through bimetallic FeCu-MOFs synthesized via a one-step laser synthesis, where Fe³⁺ and Cu²⁺ co-crystallize with tricarboxylate ligands to form an isomorphous HKUST-1 derivative. This approach exploits hard-soft acid-base principles to achieve several fundamental advances: enhanced bond strength, hydrolytic and thermal stability through the formation of robust Fe-O bonds, increasing water resistance by 20 times while preserving crystalline integrity; synergistic, delocalized energy dissipation via d-orbital charge transfer (Fe³⁺→Cu²⁺), boosting uniform photothermal conversion to 91%; and inherent stoichiometric tunability, where the Fe:Cu ratio serves as a precise performance lever, providing a design strategy to optimize stability and performance. The optimized FeCu-MOF-M variant achieves record propulsion metrics-impulse coupling coefficient (191.80 µN/W), specific impulse (631.19 s), thrust density (61.86 µN/µg), and ablation efficiency (59.32%) -surpassing monometallic HKUST-1 by 15.7% and physical mixtures by 125%. By unifying hydrolysis resistance, efficient photothermal conversion, and atomic-level tunability, this stoichiometry-driven photothermal synergy bimetallic frameworks provides a solid foundation for next-generation energetic materials in demanding environments.