Prussian blue-derived cobalt oxide/cerium oxide@carbon microsphere heterostructures for high-property electrochemical...

Efficient and sustainable extraction of freshwater from seawater is an important means to alleviate the world's water scarcity. Capacitive deionization (CDI) is considered a highly promising approach for desalination, with its performance largely dependent on the rational design of electrode materials. This work developed a Prussian blue analogue (PBA) framework-derived method to synthesis novel carbon-coated cobalt oxide-cerium oxide (Co₃O₄/CeO₂@C) microsphere heterostructures for use as CDI cathodes. The three-dimensional framework derivation enables a hierarchically porous structure, uniform metal distribution, and strong interfacial coupling between oxide phases. The Co₃O₄/CeO₂@C electrode exhibited pronounced pseudocapacitive characteristics, delivering a specific capacity of 175 F g^-1 at 1 A g^-1 and retaining 91.1% capacitance at 10 A g^-1 after 1000 cycles in a 1.0 M NaCl electrolyte. CDI tests revealed an average electrosorption capacity of 38.9 mg g^-1 in a 500 mg L^-1 NaCl solution, together with outstanding cycling stability over 300 h without detectable performance decay. Comparative experiments convincingly demonstrated the superiority of both the PBA-derived synthesis strategy and the resulting microsphere heterostructure. Furthermore, theoretical calculations elucidate the interfacial advantages of the Co₃O₄/CeO₂ heterojunction and the enhanced Na-adsorption capability induced by oxygen vacancies. This study paves a viable pathway for designing the efficient heterojunction electrodes in CDI desalination engineering.