Ni3S2@NiFePx electrode with dual-anion-modulated layer for efficient and stable oxygen evolution

The rational construction of high-performance and stable electrocatalyst for oxygen evolution reaction (OER) is a prerequisite for efficient water electrolysis. Herein, we develop a broccoli-like Ni3S2@NiFePx (Ni3S2@NFP) catalyst on nickel foam (NF) via a sequential two-step layer-by-layer assembly electrodeposition method. X-ray diffraction, in situ Raman and Fourier-transform infrared spectra have mutually validated the element segregation and phase refusion during OER condition. The reconstruction of double layer Ni3S2@NFP facilitates the formation of the active (oxy)hydroxides, which is modulated by the dual anionic layer with mixed sulfate and phosphate ions. As a result, the obtained Ni3S2@NFP electrode exhibits low overpotential (329 mV) and long-term durability (∼500 h) for OER at current density of 500 mA/cm2. Moreover, the self-supported Ni3S2@NFP can act as an efficient and durable anode in alkaline anion exchange membrane water electrolysis device (AEMWE). This work provides a facile and scaled-up strategy to construct self-supported electrocatalyst and emphasizes the crucial role of anions in pre-catalyst reconstruction and enhancing OER performance. Ni3S2@NiFePx electrode with dual-anion-modulated layer for efficient and stable oxygen evolution This work develops a broccoli-like Ni3S2@NiFePx electrode as an efficient and stable electrocatalyst for water oxidation. The unique morphology and the leaching of anions under oxidation condition facilitate the catalyst reconstruction. Meanwhile, the in situ generated dual-anion-modulated layer on the surface improved the catalytic performance and stability. [Display omitted]