A crystalline-amorphous CoS/CoOOH heterostructure enables efficient and stable SOR-coupled hydrogen evolution.

The development of efficient and durable electrocatalysts for SOR-coupled HER systems is critical for advancing sustainable hydrogen production. Herein, we present a crystalline-amorphous CoS/CoOOH heterostructure anchored on nickel foam (NF) synthesized a hydrogen peroxide-assisted hydrothermal method, where lattice-ordered CoS is partially oxidized and reconstructed into amorphous CoOOH. This crystalline-amorphous heterostructure catalytic system enhances charge transfer efficiency, reducing the SOR onset potential from 1.42 V to 0.417 V. Moreover, the resultant CoS/CoOOH@NF nanocomposite exhibits exceptional bifunctional performance in a 1.0 M NaOH + 1.0 M NaS electrolyte, achieving a current density of 100 mA cm at an ultralow potential of 0.373 V and sustaining stable operation for 40 h with negligible degradation. The enhanced activity arises from synergistic interfacial interactions, where the CoS/CoOOH@NF nanocomposite optimizes charge transfer pathways, increases active site density, and dynamically manages sulfur intermediates to prevent electrode passivation. Furthermore, the amorphous CoOOH layer acts as a self-adaptive shield, alleviating structural stress during prolonged electrolysis and resisting sulfur-induced corrosion. This work provides a novel structural regulation paradigm for designing multifunctional electrocatalysts for SOR-coupled hydrogen evolution.