Boosting efficient alkaline seawater oxygen evolution reaction of iron oxide hydroxide via plasma-induced oxygen defect engineering

Abstract

Obtaining hydrogen through direct decomposition of seawater is of major sense for alleviating the increasing shortage of freshwater resources. Nonetheless, a major obstacle to the oxidation of saltwater is the severe corrosion of anode electrodes by Cl- ions. In this work, a wet chemical technique and argon plasma treatment process were used to obtain defect-rich FeOOH/SS electrodes for OER under basic electrolyte and simulated seawater. The findings from EPR and XAFS showed that a significant amount of oxygen vacancies were generated through the plasma treatment. These vacancies promoted the activation of lattice oxygen during the oxidation of water. The findings showed that P-FeOOH/SS's plentiful oxygen vacancies supplied a sizable amount of active sites and efficient electron transfer, both of which greatly increased OER activity. Notably, when the electrolyte was simulated seawater (1.0 M KOH and 0.5 M NaCl), the overpotential reached 278 mV at 10 mA cm-2. Under these conditions, the Tafel slope was measured at 32.66 mV dec⁻¹. Furthermore, the stability was sustained at 50 mA cm-2 for a period exceeding 100 hours. Theoretical calculations showed that the high catalytic activity was primarily on account of the positive effects of oxygen defect on the electron density and d-band center of the active center. This research presented a straightforward approach for the development of efficacious defect-rich electrodes for alkaline seawater electrolysis.