Co-doped Fe3O4 nanosheets arrays on Fe foam as low-cost integrated electrocatalysts for efficient overall water electrolysis

Abstract

The development of low-cost, highly active and stable electrocatalysts is crucial for achieving high performance in hydrogen/oxygen evolution reactions (HER/OER). Herein, we utilized a simple one-step hydrothermal method to in-situ grow cobalt-doped Fe₃O₄ nanosheets arrays on iron foam (Co–Fe₃O₄/IF) as an efficient integrated electrocatalyst. The XPS demonstrated that the electronic structure of Fe₃O₄ was induced by Co-doping, improving its adsorption performance for oxygen-containing reaction intermediates. Furthermore, a series of electrochemical tests confirmed that the synthesized 22%Co–Fe₃O₄/IF possesses a significantly lower Tafel slope and charge transfer resistance, thereby enhancing the reaction rates. Hence, compared with Fe₃O₄/IF(171.4 and 370.6 mV), the 22%Co–Fe₃O₄/IF catalyst exhibits excellent activity without iR correction, requiring only 61.4 mV and 260.6 mV overpotential at 10 mA cm⁻² for HER and OER, respectively. When used as a bifunctional catalyst, the overall water splitting attested at a low voltage of 1.62 V at 10 mA cm⁻², while maintaining excellent stability.