Durable, Binder‐Free MoO 3 /Fe 2 O 3 /MoS 2 Honeycomb Heterostructure for Light‐Enhanced Water Splitting at Industrial Current Density

ABSTRACT 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 MoO 3 /Fe 2 O 3 /MoS 2 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 Fe 2 O 3 enrichment, exhibits OER activity with η 10 = 110 mV and a Tafel slope of 57.96 mV dec −1 in 1 M KOH. Whereas FeMo 8.5 having globular shape with MoS 2 ‐rich constituent, achieves a Hydrogen Evolution Reaction activity with η 10 = 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 MoO 3 /Fe 2 O 3 /MoS 2 heterojunction has been harnessed to demonstrate light integration as an impactful strategy to overcome intrinsic limitations. Under visible light illumination Fe 2 O 3 facilitates hole accumulation for OER, while MoO 3 and MoS 2 support light harvesting and charge transport. This synergy lowers kinetic barriers, delivering ∼85% enhanced OER activity in light‐assisted water electrolysis.