Oxygen defect engineering on low-crystalline iron(iii) oxyhydroxide as a highly efficient electrocatalyst for water oxidation

Abstract

Improving the water oxidation performance of non-precious nanoelectrocatalysts is the key to developing green hydrogen energy. Herein, we developed a simple method to synthesize FeOOH nanocatalysts with low crystallinity and oxygen vacancies (V_O). These catalysts demonstrate excellent electrocatalytic performance for water oxidation. The V_O-FeOOH catalyst exhibits an overpotential of 255 mV at 10 mA cm⁻² and maintains stability for more than 120 hours at a high current output (50 mA cm⁻²). DFT calculations show that the rate-determining step (RDS) of V_O-FeOOH and FeOOH is O* to OOH* (the Gibbs free energy (ΔG) of the RDS is 1.65 eV and 1.91 eV, respectively). This result indicates that V_O can effectively reduce the energy barrier from *O to *OOH of the OER process, thus improving the activity of the V_O-FeOOH nanocatalysts. Our focus was on utilizing one of the abundant metallic elements to fabricate defect-rich OER electrocatalysts with improved performance through a convenient one-step synthesis approach. This methodology shows great promise for the development of high-performance catalysts.