Symmetrical exsolution of Rh nanoparticles in solid oxide cells for efficient syngas production from greenhouse gases

Carbon dioxide and steam solid oxide co-electrolysis is a key technology for exploiting renewable electricity to generate syngas feedstock for the Fischer-Tropsch synthesis. The integration of this process with methane partial oxidation in a single cell can eliminate or even reverse the electrical power demands of co-electrolysis, while simultaneously producing syngas at industrially attractive H₂/CO ratios. Nevertheless, this system is rather complex and requires catalytically active and coke tolerant electrodes. Here, we report on a low-substitution rhodium-titanate perovskite (La_0.43Ca_0.37Rh_0.06Ti_0.94O₃) electrode for the process, capable of exsolving high Rh nanoparticle populations, and assembled in a symmetrical solid oxide cell configuration. By introducing dry methane to the anode compartment, the electricity demands are impressively decreased, even allowing syngas and electricity cogeneration. To provide further insight on the Rh nanoparticles role on methane-to-syngas conversion, we adjusted their size and population by altering the reduction temperature of the perovskite. Our results exemplify how the exsolution concept can be employed to efficiently exploit noble metals for activating low-reactivity greenhouse gases in challenging energy-related applications.