Ru-promoted NiFe oxyhydroxide anchored on the hierarchical porous N-doped carbon aerogel: Electronic structures modulation for much enhanced OER/HER dual-functional characteristics

Herein, we have demonstrated a novel Ru-promoted NiFe oxyhydroxide anchored on N-doped carbon aerogel (RuNi7FeOx(OH)y @NCA) aerogel electrocatalyst via a facile sol-gel process, combined with a supercritical drying technique. The optimal RuNi7FeOx(OH)y @NCA shows a typical "pearl-like" aerogel nanostructure with a three-dimensional network, showing a large specific surface area of 227.7 m2·g−1. The achieved RuNi7FeOx(OH)y @NCA exhibits high OER activity with a low overpotential of 278.0 mV at 10 mA·cm−2 and a high TOF of 0.107 s−1. Moreover, the RuNi7FeOx(OH)y @NCA aerogel displays excellent hydrogen evolution reaction (HER) activity under alkaline conditions, with a small overpotential of 99.0 mV at a current density of 10 mA·cm−2, and a small Tafel slope of 61.1 mV·dec−1. DFT calculations show that the enhanced OER activity is attributed to the improved binding strength of *OOH intermediate on the catalyst surface, and the introduced Ru with larger electron density and weaker spin density leads to the improved HER activity.