Interface-Growth-Assisted Molten Salt Synthesis of Cobalt-Embedded Ruthenium Oxide for Oxygen Evolution...

Ruthenium oxide (RuO₂) is the most promising alternative to iridium oxide (IrO₂) catalyst in proton-exchange-membrane water electrolysis (PEMWE). However, its practical application has been hindered by poor stability. Here, we developed an interface-growth-assisted molten salt synthesis (MSS) strategy for the preparation of stable cobalt (Co)-embedded RuO₂ (Co-RuO₂) nanorods using a lanthanum cobaltate (LaCoO₃) template. The MSS environment is beneficial for anisotropic growth and the exposure of highly active RuO₂ crystal planes. Moreover, the in situ topological transformation arising from the interface growth of RuO₂ on LaCoO₃ can further enhance these effects and incorporate Co into the RuO₂ lattice. The PEMWE electrolyzer with Co-RuO₂ as the anode catalyst can operate steadily for over 300 h at 500 mA cm^-2. Theoretical simulations indicate that Co substitutions would stabilize oxygen vacancies and increase metal-oxygen covalency, thereby lowering cell voltage and improving the stability of the PEMWE electrolyzer. This work pioneers template-directed interface growth in an MSS environment to prepare anisotropic RuO₂ catalysts for practical PEMWE applications.