Innovative PES modified with Sodium titanate/titanium dioxide nanocomposite as a flexible electrode for Efficient photoelectrochemical water splitting

Flexible photoelectrochemical (PEC) electrodes are vital for the development of adaptable and efficient PEC devices. In this work, flexible nanocomposite films were fabricated by incorporating TiO₂@Na₂Ti₃O₇ (STO) into polyether sulfone (PES) via the phase inversion method. A series of PES/xSTO films with varying STO contents (0–0.08 wt.%) was synthesized and systematically characterized to evaluate their structural, morphological, and optical properties. Incorporation of STO into PES reduced the band gap from 3.577/2.728 eV (pure PES) to 3.501/2.647 eV (0.04 wt.% STO), improving light absorption. PEC measurements revealed that the PES/0.04 STO film exhibited the best performance, with a photocurrent density of 3.24 mA/cm²—nearly 15 times higher than pure PES. This enhancement was attributed to suppressed electron–hole recombination. The optimized film achieved an incident photon-to-current efficiency (IPCE) of 11.1% and an applied bias photon-to-current efficiency (ABPE) of 0.41% at 470 nm. Furthermore, the influence of light intensity, temperature, and reusability on electrode performance was assessed. These results demonstrate the promise of PES/STO nanocomposites as flexible, high-performance electrodes for sustainable hydrogen production.