Durable, Binder-Free MoO₃/Fe₂O₃/MoS₂ Honeycomb Heterostructure for Light-Enhanced Water Splitting at Industrial...

Hydrogen production via alkaline water electrolysis is limited by sluggish oxygen evolution reaction (OER) kinetics, poor durability of electrocatalysts, and the energy-intensive synthesis of these catalysts. Herein, we report ligand-assisted, temporal decoupling strategy in solvothermal synthesis of FeMo bifunctional electrocatalysts with a unique MoO₃/Fe₂O₃/MoS₂ heterojunction. Dimethyl formamide-extract of lemon grass serves as the effective binder to Industrial grade Ni-Foam (NF) substrate. Synthesized electrocatalyst FeMo_5.6 with a nanoflake morphology and Fe₂O₃ enrichment, exhibits OER activity with η₁₀ = 110 mV and a Tafel slope of 57.96 mV dec^-1 in 1 M KOH. Whereas FeMo_8.5 having globular shape with MoS₂-rich constituent, achieves a Hydrogen Evolution Reaction activity with η₁₀ = 89 mV. Moreover, a two-electrode configuration comprising FeMo_5.6/NF || FeMo_8.5/NF requires only 2.4 V to reach current density of 450 mA cm^-2 with ∼100% Faradaic efficiency and stable operation for over 500 h. In addition to that, visible light harvesting capability of MoO₃/Fe₂O₃/MoS₂ heterojunction has been harnessed to demonstrate light integration as an impactful strategy to overcome intrinsic limitations. Under visible light illumination Fe₂O₃ facilitates hole accumulation for OER, while MoO₃ and MoS₂ support light harvesting and charge transport. This synergy lowers kinetic barriers, delivering ∼85% enhanced OER activity in light-assisted water electrolysis.