Hierarchically Structured Ti-TiO2 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-TiO₂ 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 TiO₂ (10 and 100 nm) yielded conformal coatings with tunable crystallinity. Among the tested configurations, the 100 nm TiO₂ 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^-2 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.