Boron‐Doped Carbon Overlayers Conquer Sulfur Poisoning of Nickel‐Based Catalysts for Ultrastable Low‐Energy Hydrogen Production Coupled With Sulfion Oxidation

Abstract

ABSTRACT Replacing the oxygen evolution reaction with the sulfion oxidation reaction (SOR) offers a promising route to low‐energy hydrogen production, yet conventional catalysts are rapidly deactivated by sulfur poisoning. Herein, we report a boron‐doped carbon‐coated nickel catalyst (Ni@BC) that overcomes this challenge. Boron incorporation moderately enhances carbon–sulfur orbital coupling, optimizing sulfur adsorption to enable a stepwise pathway with facile S 8 desorption and complete suppression of insulating sulfur accumulation. Ni@BC thus delivers an ultralow SOR overpotential (0.294 V at 10 mA cm −2 ) and record durability exceeding 1500 h without degradation. Concurrently, boron doping promotes the hydrogen evolution reaction (HER) by facilitating water adsorption and dissociation and tuning the hydrogen adsorption free energy to near thermoneutral, achieving an overpotential of 38.7 mV at 10 mA cm −2 and surpassing commercial Pt/C at high current densities. A symmetric electrolyzer employing Ni@BC as both electrodes needs only 0.573 V at 100 mA cm −2 , with stable operation exceeding 440 h and simultaneous sulfur recovery. When scaled up to a 50 cm 2 continuous‐flow electrolyzer, the system maintains an ultralow voltage of 0.70 V at 5 A, while enabling stable hydrogen generation and gram‐scale sulfur production for over 200 h.