Transition Metal/Metal Sulfide Heterostructures Boost Energy Saving Hydrogen Production Coupled with Sulfion Degradation

Hydrogen production through the electrochemical hydrogen evolution reaction (HER) provides a promising pathway for sustainable and green energy. Coupling HER with the thermodynamically favorable sulfion oxidation reaction (SOR) can reduce energy consumption and recycle industrial by-product S^2-. However, the development and practical application are hindered by the lack of cost-effective and robust catalysts. Herein, we constructed a bifunctional electrode with rich metal/metal sulfide heterostructures using NiFe foam through stepwise electrodeposition and hydrothermal sulfurization (NiFe-CrCoMo-S). Benefiting from the hydrophilic and sulfur-repellent surface and rich metal/metal sulfide heterostructures, it delivers outstanding SOR and HER performance. The integrated cell, utilizing the NiFe-CrCoMo-S electrode for both the cathode and anode, achieves a remarkable cell voltage of 0.75 V at a current density of 200 mA cm^-2, which is 1.43 V lower than conventional water electrolysis. It demonstrates extraordinary long-term durability over 1100 hours without significant decay, achieving high Faradaic efficiencies (≥99%) and low electricity consumption (1.79 kWh m^-3 H₂) for hydrogen production. This work paves the way for environmentally friendly strategies, combining cost-effective hydrogen production with value-added sulfur recovery, offering a reliable option for bifunctional catalyst design.