Harvesting Green Hydrogen from the Deep Blue: Seawater‐Compatible SnSe‐P Decorated Graphene‐CNTs Based Electrocatalyst Under Universal pH

Abstract Fabrication of cost‐effective and robust metal‐based electrocatalysts for hydrogen evolution reactions (HER) across the entire pH range has garnered significant attention in harvesting renewable energy. Herein, the fabrication of 3D high‐surface Ni Foam‐Graphene‐Carbon Nanotubes (NGC) decorated with phosphorous‐inserted tin selenide (SnSe‐P) showcases unprecedented HER activity with minimal overpotentials across all pH ranges (52 mV in acidic, 93 mV in basic, and 198 mV in neutral conditions@10 mA cm −2 ) and stability at 1 A cm −2 for 72 h. The as‐designed catalyst shows a low overpotential of 122 mV@10 mA cm −2 in alkaline seawater, achieved through controlled electronic distribution on Sn site after incorporation of P in NGC‐SnSe‐P. A stable cell voltage of 1.56 V@10 mA cm⁻ 2 is achieved for prolonged time in 1 m KOH toward overall water electrolysis. Experimental and theoretical investigation reveals that the insertion of P in layered SnSe enables s orbitals of H * and p orbitals of Sn to interact, favoring the adsorption of the H * intermediate. A renewable approach is adopted by using silicon solar cells (η = 10.66%) to power up the electrolyzer, yielding a solar‐to‐hydrogen (STH) conversion efficiency of 7.70% in 1 m KOH and 5.65% in alkaline seawater, aiming toward green hydrogen production.