Conjugated Polymer-Supported\nDoped Bi<sub>2</sub>WO<sub>6</sub> S‑Scheme Heterojunction\nfor Proficient Water Splitting\nvia Dual Regulation of Band Gap Engineering and Improved Charge Separation

Designing potent photocatalysts for water splitting is\none of the\nforemost challenges in operative solar energy harvesting, and particularly,\nexploring Bi<sub>2</sub>WO<sub>6</sub>-based photocatalysts remains\nunresolved due to its intrinsic drawbacks of fast charge recombination,\npoor conductivity, and inadequate catalytic efficiency. Herein, we\npresent a strategy to tune the band gap of molybdenum-doped Bi<sub>2</sub>WO<sub>6</sub> (Mo-Bi<sub>2</sub>WO<sub>6</sub>) by an amalgamation\nof conducting polymer nanofibers for efficient hydrogen generation\nvia photocatalytic water splitting. The heterostructures mimic natural\nphotosynthetic systems via S-scheme charge transfer, utilizing the\nconducting polymer component to harvest photons for reduction reaction\nand the transition metal part to hasten catalytic activities by facile\ncharge transfer, which drastically lowers the transport resistance,\nas reflected in impedance spectra. The optimal content of 2 wt % Mo-BiWO<sub>6</sub> as a cocatalyst in the heterostructures reaches a remarkable\nH<sub>2</sub> production rate of 131 mmol g<sup>–1</sup> h<sup>–1</sup> with an 18% higher apparent quantum efficiency than\npure PPy. Moreover, the heterostructure displays 200- fold higher\nphotocurrent density with fortuitous photostability. The presence\nof PPy efficiently suppresses charge recombination of Mo-Bi<sub>2</sub>WO<sub>6</sub> and improves interfacial charge transfer at the heterostructure.\nThe dominant factor for higher photocatalytic activity is proposed\nbased on a femtosecond transient absorption spectra study supported\nfurther by time-resolved photoluminescence spectra and valence band\nX-ray photoelectron spectroscopy. This work provides a facile approach\nto developing high-performance, noble-metal-free visible light-driven\nphotocatalysts for efficient solar-fuel production.