High-Performance Alkaline Freshwater and Seawater Hydrogen Catalysis by Sword-Head Structured Mo2N-Ni3Mo3N Tunable Interstitial Compound Electrocatalysts
Realizing efficient electrocatalysts is a stepping stone toward achieving high-performance alkaline water/seawater electrolysis, but remains a crucial challenge. Herein, heterogeneous Mo 2 N/Ni 3 Mo 3 N electrocatalysts on nickel foam (denoted MN-NMN/NF) that is stable and active for the hydrogen evolution reaction (HER) in both alkaline water/seawater are demonstrated. The optimized MN-NMN09/NF achieves an ultralow HER overpotential of 11 mV@10 mA cm −2 in 1.0 m KOH electrolyte, which is not only superior to the benchmark Pt/C catalysts but also the best reported ever among NiMo-based electrocatalysts in an alkaline environment. Successively, the optimized MN-NMN09/NF electrocatalyst can drive HER current densities of 10 and 500 mA cm −2 using low overpotentials of 9.37 and 123 mV in 1.0 m KOH seawater electrolyte, which remains durable after 120 h long-term electrolysis at a constant current density of 500 mA cm −2 . In situ Raman analysis reveals that the enhanced performance is attributed to the accelerated H 2 O adsorption and OH dissociation processes on the MN-NMN surfaces. Theoretical analysis further confirms that rapid H 2 O adsorption-dissociation kinetics and H adsorption-conversion kinetics on the Ni 3 Mo 3 N/NiOOH and Ni 3 Mo 3 N/MoO x surfaces result in boosted HER capability. This work depicts a significant potential for designing stable and efficient hydrogen production electrocatalysts for both alkaline water and seawater electrolysis.
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