Interface-Engineered Delafossite CuCoO ₂ /CuO Heterojunction Catalyst for Ammonium Dinitramide Monopropellants

Ammonium dinitramide (ADN)-based monopropellants such as LMP–103X offer a lower-toxicity alternative to hydrazine; however, their application is limited by poor cold-start capability that demands energy-intensive ignition. We report a nonprecious CuCoO2 delafossite and its CuCoO2/CuO heterojunction, synthesized through optimization of the Cu:Co precursor ratio, that enhance the catalytic decomposition and significantly reduce the ignition temperature of LMP–103X. Phase evolutions in the catalysts was characterized by PXRD, and the heterostructure and morphology were investigated using SEM and TEM. The optimal Cu:Co (2:1) composition facilitated the formation of a CuCoO2/CuO heterojunction, which lowered the decomposition peak by 55 °C compared to the uncatalyzed monopropellant. XPS analysis reveals the coexistence of multivalent cations (Co3+/Co2+ and Cu+/Cu2+) and a high density of oxygen vacancies that enhance redox activity and interfacial charge transfer, and postreaction surface analysis identifies Co3+ and Cu+ sites that drive the catalysis. The enhanced catalytic performance at the optimized metal ratios is attributed to the higher density of heterojunction interfaces that promotes efficient charge transport and redox cycling.