Sustained Solar-Powered Electrocatalytic H₂ Production by Seawater Splitting Using Two-Dimensional Vanadium Disulfide

Robust and stable electrodes made from earth-abundant materials have gained widespread interest in large-scale electrocatalytic water splitting toward hydrogen energy technologies. In this study, the vanadium disulfide (VS 2 )/amorphous carbon (AC) heterostructure was employed as an electrode for direct seawater splitting. Two-dimensional VS 2 nanoparticles were deposited on AC with a high degree of uniformity via a well-optimized one-step chemical vapor deposition approach. The VS 2 /AC heterostructure electrode was found to possess rich active sulfur sites, near-zero Gibbs free energy, a large surface area, and exceptional charge transfer toward the electrolyte, resulting in enhanced hydrogen evolution reaction (HER) performance with a low onset potential and low overpotential of 11 and 61 mV (vs reversible hydrogen electrode (RHE)), respectively. The electrode also sustained robust stability throughout the 50 h of chronoamperometry studies under acidic electrolyte conditions. Interestingly, the VS 2 /AC electrocatalyst accomplished an exceptional HER performance under natural seawater conditions in the absence of an external electrolyte with an onset potential of 56 mV vs RHE and attained η 200 at an overpotential of 0.53 V vs RHE. In spite of this, the heterostructure exhibited superior stability over 21 days at a high current density of 250 mA/cm 2 under both indoor and solar-powered outdoor conditions. Overall, this VS 2 /AC heterostructure may open a new pathway toward direct seawater splitting for long-term, stable, large-scale hydrogen generation.