Hierarchically Structured Ti-TiO Membranes Fabricated by Femtosecond Laser Ablation and Atomic Layer Deposition for Enhanced Photoelectrochemical Water Splitting.

Efficient and scalable photoelectrodes are essential for advancing solar-driven hydrogen production via photoelectrochemical (PEC) water splitting. This work presents a novel binder-free Ti-TiO membrane photoanode engineered by the synergy of femtosecond laser ablation and atomic layer deposition (ALD). Laser processing produced a highly ordered array of micro pyramids on titanium foil, significantly increasing the surface area and light-trapping capability. Subsequent ALD of TiO (10 and 100 nm) yielded conformal coatings with tunable crystallinity. Among the tested configurations, the 100 nm TiO layer showed superior performance, attributed to its enhanced crystallinity, optical absorption, and charge transport properties. The optimized membrane achieved a photocurrent density of ∼27 μA cm at 1.4 V vs NHE, an IPCE (Incident photon to current conversion efficiency) of ∼31% at 275 nm, and a 3-fold increase in ABPE (Applied Bias Photon-to-current Efficiency) compared to the uncoated sample. This strategy presents a scalable and reproducible approach to high-performance, binder-free photoanodes for solar hydrogen production.