Electronic Synergism in Amorphous Zr _0.9 Mn _0.1 (OH) _4‐δ for Enhanced Electrocatalytic Green Hydrogen Production in Alkaline Seawater

ABSTRACT Amorphous Zr _1‐x Mn _x (OH) _4‐δ have been investigated toward highly active and robust electrocatalytic hydrogen evolution reaction (HER). Zr _0.9 Mn _0.1 (OH) _4‐δ demonstrates the best HER activity among different metal‐substituted (Zr _0.9 M _0.1 (OH) _4‐δ ; M = Ni, Co, Cu, and Fe) as well as varied Mn‐substituted systems (Zr _1‐x Mn _x (OH) _4‐δ ; x = 0.05, 0.15, 0.2, and 0.3). It achieves an overpotential (ƞ ₁₀ ) of 91.3 mV (at j = 10 mA cm ⁻² ) in 1 M KOH. Zr _0.9 Mn _0.1 (OH) _4‐δ also exhibits prominent HER activity in stimulated alkaline seawater (ƞ ₁₀ = 98.8 mV) and alkaline seawater (ƞ ₁₀ = 114 mV), accompanied by prolonged durability in seawater conditions. The multi‐step chronopotentiometry exhibits good mass transport and charge‐transfer abilities during HER. The improved activity arises from the nanosheet‐like structure, having more exposed surface, and oxygen vacancy. Theoretical calculations suggest that Mn‐Zr synergy in Zr _0.9 Mn _0.1 (OH) _4‐δ enhances the electronic pπ‐dπ coupling, which improves the H ^* adsorption ability and reduces the energy barrier for HER. The two‐electrode cell configured as Zr _0.9 Mn _0.1 (OH) _4‐δ ║RuO ₂ demonstrates a low voltage of 1.59 and 1.7 V (j = 10 mA cm ⁻² ) in both media, which is further tested to produce green hydrogen employing solar energy. Thus, the work demonstrates the viability of amorphous Zr _0.9 Mn _0.1 (OH) _4‐δ as a promising candidate for green hydrogen production.