In-situ constructed Ru-rich porous framework on NiFe-based ribbon for enhanced oxygen evolution reaction in alkaline solution

Exploiting economical and high-efficient electrocatalysts of oxygen evolution reaction (OER) remains urgent in the field of sustainable hydrogen generation by water electrolysis. Ru- and Ir-based materials are benchmark electrocatalysts towards the OER, yet the precious metals are expensive and scarce. Herein, we develop a kind of Ru-doped NiFe-based catalyst with three-dimensional nanoporous surface (NP-Ru_x), which fulfils both performance and cost requirements for the OER electrocatalysis. This novel material can directly work as a support-free electrode and exhibits excellent OER performance with an ultralow overpotential of 245 mV at 10 mA cm⁻² and a small Tafel slope of 15 mV dec⁻¹ as well as low charge transfer resistance. The superior performance could be rationalized as follows: (1) Generated Ru-rich nanoporous architecture can not only supply a large number of active sites but also facilitate mass transfer at the electrode/electrolyte interface; (2) Multiple metals (hydro)oxides generated on the surface have the synergistic catalytic effect for the OER; (3) The in-situ generation of (hydro)oxides and the firm bonding of nanoporous layer and the substrate allow for easy electron transfer. These features make NP-Ru_x a promising oxygen-evolving electrode material toward water electrolysis.