Constructing Electron-Deficient environment in FeCoNiW Medium-Entropy alloys towards efficient alkaline oxygen evolution reaction

• Electron-deficient environment stabilizes the formation of the key OOH* intermediate. • Lattice distortion generates microstrain and abundant unsaturated sites. • The catalyst shows 255 mV overpotential (10 mA cm −2 ), a Tafel slope of 59.1 mV dec -1 , and 150 h chronoamperometry operational stability. The sluggish kinetics of oxygen evolution reaction (OER) presents a central challenge to the overall efficiency of water electrolysis and the modulation of the adsorption strength of oxygenated intermediates, particularly the critical OOH* species is crucial to fasting OER kinetics. Herein, a new strategy to stabilize OOH* intermediate through constructing electron deficient environment in FeCoNiW/C medium-entropy alloys electrocatalyst is reported. The designed electrocatalyst achieves a low overpotential of 255 mV at a current density of 10 mA cm −2 , 61 mV lower than that for commercial RuO 2 , and a small Tafel slope of 59.1 mV dec -1 . Moreover, it also can be operated stably with a voltage decay of only 0.1 mV h −1 in 100 h at 100 mA cm −2 . That superior activity can be attributed to the introduction of highly electronegative element of W, which modulates the electronic structure of Fe/Co/Ni sites and creates a localized electron-deficient environment. In situ FTIR and density functional theory calculations suggest this electron-deficient feature of active sites can facilitate the adsorption of oxygen-containing intermediates and promote the formation of the OOH*, which is rate-determining step for water oxidation. This work also offers a new strategy for the modification and design of advanced OER electrocatalysts.