Abstract
The development of catalysts capable of selectively converting CO₂ into short-chain hydrocarbons remains a central challenge in sustainable catalysis. Here, we report a reaction-driven exsolution strategy in multi-metallic spinel ferrites that enables the in-situ formation of active nanocomposite phases during CO₂ hydrogenation, eliminating the need for any pre-treatments. We also demonstrate that depending on the exsolution environment, we can produce single metal and/or ternary nanoparticles. Operando spectroscopy reveals a bifunctional tandem mechanism, in which Cu and Ni sites catalyse CO₂ activation, while the iron carbide phases, dynamically forming under reaction conditions, promote C–C coupling and hydrocarbon chain growth. This reaction-induced restructuring leads to enhanced activity and selectivity toward short-chain hydrocarbons. These findings identify reaction-driven exsolution as a strategy for controlling active phase formation under working conditions, defining a direct relationship between exsolution dynamics and catalytic performance and providing new insight into the design of energy-efficient, adaptive catalysts.