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

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.