Highly Salt-tolerant hydrogen evolution reaction based on dendritic urchin-like MoC/MoS₂ heterojunction in seawater

The direct electrolysis of abundant near-neutral seawater resources for hydrogen production faces significant challenges due to insufficient catalyst activity and salt toxicity. Herein, we demonstrate a novel dendritic urchin-like MoC/MoS₂ heterojunction in-situ formed on carbon cloth (CC@MoC/MoS₂-H) through a combination of hydrothermal and high-temperature annealing processes. This unique dendritic urchin-like structure consists of numerous nanorods on carbon cloth, which enhances the catalytic active sites and provides space for efficient bubble release. The resulting CC@MoC/MoS₂-H exhibits superior catalytic performance, with an overpotential of 91 mV and 136 mV at the current density of 10 mA cm⁻² in the 1 M PBS electrolyte and natural seawater, respectively, surpassesing that of most non-noble metal compounds reported previously. Finite element simulations reveal that the urchin-like structure has significantly higher bubble release capacity compared to the randomly stacked structure. Additionally, the urchin-like structure demonstrates substantially greater current density retention under electrolytic conditions designed to simulate salt accumulation, in comparison to the small-size structure. Furthermore, the average H₂ production efficiency of 78,493 μmol h⁻¹ g⁻¹ was evaluated for three consecutive hours using commercial solar panels rated at 2 V on a large-scale electrode assembly from seawater, which is comparable to the present photocatalytic hydrogen production efficiency. This work opens new avenues for the development of catalytic structures compatible with seawater.