Modulating electronic by construction WS2/WN heterostructure coupled with N-doped carbon to boost alkaline seawater hydrogen production

The development of an efficient and durable non-precious electrocatalyst for alkaline seawater electrolysis is of great significance. Herein, two-dimensional (2D) lamellar heterostructure WS2/WN was dispersed on the carbon matrix (marked as WS2/WN@CM). The obtained WS2/WN@CM catalysts demonstrate exceptional performance in the hydrogen evolution reaction (HER) in alkaline freshwater (1.0 M KOH), alkaline simulated seawater (1.0 M KOH + 0.5 M NaCl) and alkaline natural seawater (1.0 M KOH + seawater), respectively, which achieved a low overpotential (92 mV, 95 mV and 113 mV) at 10 mA cm(-2) and outstanding long-term durability at 200 mA cm(-2) for 100 h. The catalyst benefits from the 3D carbon skeleton, which not only effectively prevents stacking of the 2D lamellar WS2/WN to fully utilize the active material, but also provides rapid electron transport. Moreover, stress effects at WS2/WN interfaces lead to distortions of torsion angles in the WS2 lattice, thereby increasing crystal surface defects accompanied by an enhancement of electrical conductivity. Density functional theory (DFT) calculations combined with XPS evidence confirm the electronic structure reorganization of WS2/WN at interfaces, which optimizes the adsorption energy of specific intermediates. Additionally, WN captures many electrons from WS2, so the WN region favors the reduction reaction and thus enhances the HER process.