Engineering Mo-Doped Sulfide Heterointerfaces from POM-MOFs for Enhanced Alkaline Seawater Hydrogen Evolution

Hydrogen production via seawater electrolysis offers great potential for clean energy; however, sluggish kinetics and corrosive ions hinder the efficiency. Hence, the fabrication of economically viable and robust electrocatalysts is essential for effective alkaline seawater splitting. Herein, Mo-doped CuS/NiS interfaces supported on nickel foam (Mo-CuS/NiS/NF) were designed using polyoxometalate-based metal-organic frameworks (POM-MOFs) through a scalable hydrothermal strategy for the electrocatalytic hydrogen evolution reaction (HER). The enhanced features provide exposed active sites and offer low overpotentials, leading to enhanced HER performance under alkaline seawater conditions. Experimental and theoretical analyses revealed successful Mo doping, the formation of dual transition-metal sulfide (TMS) interfaces, and a decreased Gibbs free energy (merely 0.08 eV for Mo-CuS and -0.70 eV for Mo-NiS) of the rate-determining step. Optimized Mo-CuS/NiS/NF required low overpotentials under alkaline (78 mV), simulated (95 mV), and real seawater conditions (111 mV), surpassing 20% Pt/C@NF at 10 mA cm^-2 while remaining stable for over 50 h. Therefore, Mo-doped CuS/NiS interfaces supported on NF provide a guideline for significant advancements in the synthesis of highly efficient POM-MOF-derived sulfide electrocatalysts for electrocatalytic water splitting with enhanced performance, stability, and practicality.