Designing titania nanotube architectures through anodization for high-performance green hydrogen generation

The exhaustion of non-renewable resources highlights the urgency of renewable alternatives, with green hydrogen production as a key focus. This study systematically investigates voltage-dependent morphological evolution of TiO₂ nanotube arrays (12 V, 20 V, 30 V) synthesized via anodization and establishes quantitative structure-property-performance relationships for photoelectrochemical water splitting. Morphological characterization revealed that 12 V produced irregular, cracked structures, while higher voltages yielded well-defined tubular architectures: 20 V exhibited 42.2 ± 3.8 nm diameter nanotubes with 13.5 ± 1.2 nm wall thickness and 43.0 ± 2.8% porosity; 30 V produced larger tubes (66.7 ± 5.2 nm diameter, 15.8 ± 1.5 nm walls, 60.0 ± 3.5% porosity). XRD analysis confirmed pure anatase phase formation with crystallite sizes of 33.9 ± 2.8 nm, 39.8 ± 3.2 nm, and 45.4 ± 3.6 nm for 12 V, 20 V, and 30 V samples, respectively. XPS, BET, and TEM analyses provided comprehensive validation of chemical composition, surface area (38.2–52.7 m²/g), and nanostructure. Photoelectrochemical measurements demonstrated progressive enhancement with voltage: photocurrent densities of 0.12, 0.58, and 0.95 mA cm⁻² at 1.23 V vs. RHE, corresponding to hydrogen evolution rates of 0.08 ± 0.01, 0.14 ± 0.02, and 0.20 ± 0.02 mL h⁻¹ , with efficiencies reaching 7.18% at 30 V. This 2.5-fold performance improvement demonstrates that significant enhancement can be achieved through morphological optimization alone, providing essential baseline data and design principles for advanced photoelectrochemical hydrogen generation systems.