Dynamic anion regulation to construct S-doped FeOOH realizing 1000 mA cm−2‑level‑current‑density oxygen evolution over 1000 h

Iron oxyhydroxide (FeOOH) as the real active species of Fe-based electrocatalysts holds great promise in industrial water electrolysis. However, the poor conductivity and OER kinetics hinder its catalytic performance. Herein, we have developed a facile dynamic anion regulation strategy to enhance OER activity of FeOOH. Of the seven common anions (VO33-, MoO42-, WO42-, S2-, H2PO4-, H2PO2- and F-), S2- was found to have the best regulatory effect. The obtained 0.01 S-FeOOH+1000/IF exhibits industrial-level OER current output of 1000 mA cm−2 with low overpotential of 358 mV. Importantly, this catalyst can operate stably at 1000 mA cm−2 for at least 1000 h. Theoretical calculation reveals that the doping of sulfur can drastically lower the energy barrier of rate-determining step during OER. Meanwhile, 0.01 S-FeOOH+1000/IF in alkaline anion exchange membrane (AEM) cells demonstrates a stable cell voltage of 2.12 V to reach 1000 mA cm−2 over 24 h.