Construction of Fe₂O₃ Nanosheet Arrays by Sulfur Doping toward Efficient Alkaline Hydrogen Evolution

It is indispensable to explore earth-abundant and high-efficiency transition-metal-oxide electrocatalysts toward the hydrogen evolution reaction (HER). However, their catalytic performance is impeded by the poor conductivity. Herein we rationally design and manufacture sulfur-doped Fe2O3 nanosheet arrays grown on iron foam (S-Fe2O3/IF) with enhanced HER performance in alkaline media. The obtained catalyst exhibits a low overpotential of 134 mV to achieve a current density of 10 mA cm–2 with a small Tafel slope of 76 mV dec–1 and shows an excellent long-term durability with barely any degradation for 50 h. The density functional theory calculation and experimental results demonstrate that the sulfur anion could optimize adsorption free energies of hydrogen/water and improve the intrinsic activity of Fe2O3. This work not only develops a catalyst with highly efficient performance but also provides design guidance to rationally manufacture an earth-abundant-element electrocatalyst for large-scale water splitting to hydrogen.