Layered FeMo2S4-packed hexagonal nitrogen-doped carbon microsheets embedded with Fe3C nanoparticles for efficient electrocatalytic oxygen evolution reaction

The design of efficient, low-cost non-noble metal oxygen evolution reaction (OER) catalysts has attracted considerable attention. Fe₃C sites have excellent catalytic effects arising from their high electrical conductivity and numerous active sites. Moreover, the high–valence state of molybdenum significantly enhances the electrochemical performance of electrocatalysts. Herein, we propose a design strategy through which hexagonal Fe₃C/NC microsheets can be successfully synthesised using a self-template. This strategy also demonstrates how the surfaces of hexagonal microsheets can be covered with FeMo₂S₄ nanosheets with active sites via hydrothermal and secondary calcination. FeMo₂S₄–Fe₃C/NC exhibits outstanding catalytic performance, achieving a current density of 10 mA cm⁻² with an overpotential of only 243 mV, Tafel slope of 32 mV dec⁻¹, and excellent stability for up to 50 h. The number of active sites on the catalyst surface can be increased by introducing Mo and S, which effectively change the structure of the electronic environment. This study presents a new method of designing simple and efficient non-precious-metal catalysts with excellent performance for use in OER.