Ethanol-regulated iron corrosion for fabricating RuOx/FeOOH electrocatalyst toward enhanced hydrogen evolution

Abstract

RuOx is a promising electrocatalyst for the hydrogen evolution reaction (HER), but it suffers from competition between *OH and *H adsorption and the over-binding effect of H on the RuOx surface. FeOOH features strong oxophilicity, making it expectedly form RuOx/FeOOH composite to efficiently catalyze HER. Considering the strong oxidability of Ru3+, it is desirable to design a moderate environment to form a RuOx/FeOOH composite with a homogeneous structure and accessible Ru sites. Herein, an ethanol-regulated corrosion strategy was developed to in-situ grow RuOx/FeOOH electrocatalyst on iron foam. To avoid the violent redox reaction, the coordination of hydroxyl groups in ethanol with Ru3+ reduces the oxidability and postpones the diffusion of Ru3+ ions. The prepared catalyst exhibited a low over-potential of 67 mV at 50 mA cm−2 and excellent water-splitting properties requiring 1.56 V at 100 mA cm−2 due to the optimized structure and the strong electron interaction between RuOx and FeOOH. According to the modulation mechanism of hydroxyl groups, ethylene glycol, n-propanol, isopropanol, and methanol are substitutable for ethanol to boost the HER activity of RuOx/FeOOH. This work proposes a coordination-regulation approach for preparing Ru-based composite catalysts with enhanced HER performance by adjusting iron corrosion behaviors.