Energy-Saving Hydrogen Production by Seawater Splitting Coupled with PET Plastic Upcycling

Abstract

<p>Direct seawater electrolysis presents a promising route for grid-scale green hydrogen (H2) production without reliance on scarce freshwater. However, it is severely hampered by high energy consumption (> 4.3–5.73 kWh m−3 H2) and harmful chlorine corrosion. Herein, an energy-saving and chlorine-free H2 production system by coupling seawater splitting and upcycling of polyethylene terephthalate (PET) waste into value-added glycolic acid (GA) over a Pd─CuCo2O4 catalyst is reported. An ultra-low potential of 1.15 V versus RHE is required to achieve an industry-level current density of 600 mA cm−2, which reduces electricity cost to 2.45 kWh m−3 H2. Notably, this system maintains 1.6 A for longer than 100 h, demonstrating excellent stability. Experimental and theoretical results unveil that 1) the specific adsorption of PET-derived ethylene glycol (EG) on Pd enhances the catalytic performance, and the downshifted d-band center of Pd accelerates the desorption of GA to prevent over-oxidation; 2) the strong adsorption of OH− on CuCo2O4 synergistically promotes EG electrooxidation (EGOR) and forms a negative charge layer that effectively repels Cl− by electrostatic repulsion, thus preventing chlorine corrosion. This work may provide new opportunities for H2 production and value-added GA from vast marine resources and PET waste.</p>