Manipulating surface buffer of transition metal sulfide for robust seawater electrolysis

Abstract

Developing highly active and robust transition-metal electrocatalysts for seawater electrolysis is pivotal for industrially relevant green hydrogen production, yet remains a great challenge. Herein, we reported a novel hybrid nickel-chromium sulfide-based electrocatalyst (NiCrS/CN), integrating NiCrS with nitrogen-doped carbon shell encapsulation, to manipulate sulfur migration. Benefiting from nitrogen-doped carbon (C-N) layer interfacial regulation, the obtained NiCrS/CN electrocatalytic system demonstrates an outstanding seawater splitting performance. Accelerating hydrogen evolution reaction (HER) kinetics with corresponding overpotentials as low as 143, 164, and 191 mV to -50, -100, and -200 mA cm^-2 in alkaline seawater electrolyte, respectively, is observed for the NiCrS/CN electrode. Notably, our NiCrS/CN electrolyzer can stably produce an industrial current density of 50 mA/cm² at a potential of 1.40 V, 120 mV lower in energy potential than that of the NiCrS (1.52 V) electrolyzer in an alkaline seawater system. Remarkably, our NiCrS/CN system can stably maintain a superior 1200-hour electrolysis in alkaline electrolyte. Even under seawater conditions, the rationally designed NiCrS/CN electrolyzer can be stably operated for at least 100 h to achieve industrially relevant hydrogen production from seawater splitting. Such a striking performance is attributed to C-N layer encapsulation, which not only induces a strong synergistic effect to optimize local electronic configuration, but also manipulates an alkaline micro-environment for Cl^- buffer as well as S migration, resulting in a robust industrial-relevant seawater splitting for hydrogen generation.

Keywords

Cost-effective electrocatalyst / transition-metal sulfides / nitrogen-doped carbon layer / seawater splitting / synergistic effect

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