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

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.