A strongly coupled Pt-W2N heterostructure embedded in porous carbon nanoflowers for seawater electrolysis

Abstract

Constructing heterostructures with favorable catalytic activities is crucial for improving the seawater electrolysis. Herein, we report a strongly coupled Pt-W₂N heterostructure embedded within porous conductive carbon nanoflowers (Pt-W₂N@C) as a highly efficient and durable cathode electrocatalyst for seawater electrolysis. Through in situ Raman spectroscopy and electrochemical analysis, we elucidate that the Pt-W₂N@C system leverages synergistic electronic interactions at the heterointerface to concurrently optimize the adsorption of H* and OH* intermediates while enhancing water dissociation kinetics. The optimized Pt-W₂N@C catalyst exhibits superior hydrogen evolution reaction (HER) performance across acidic, neutral, and alkaline electrolytes, achieving overpotentials of 1.2, 7, and 32.2 mV, respectively, at 10 mA cm⁻², significantly outperforming commercial 20 wt% Pt/C benchmarks. Notably, the Pt-W₂N@C catalyst exhibits exceptional performance in alkaline seawater electrolysis, achieving ultra-low HER overpotential (163.8 mV at 700 mA cm⁻²) alongside superior chloride tolerance and HER performance under 0.5–2.5 M NaCl. Remarkably, in a practical seawater electrolyzer (Pt-W₂N@C∥ NiFe-layered double hydroxide (LDH)), it requires only 1.992 V to drive 500 mA cm⁻² while maintaining 95.8% activity retention over 80 h of continuous operation. These findings highlight the advantages of heterostructures and their cooperative effects in designing next-generation electrocatalysts for practical seawater electrolysis.