Conjugated Polymer-Supported Doped Bi2WO6 S-Scheme Heterojunction for Proficient Water Splitting via Dual Regulation of Band Gap Engineering and Improved Charge Separation

Abstract

Designing potent photocatalysts for water splitting is one of the foremost challenges in operative solar energy harvesting, and particularly, exploring Bi₂WO₆-based photocatalysts remains unresolved due to its intrinsic drawbacks of fast charge recombination, poor conductivity, and inadequate catalytic efficiency. Herein, we present a strategy to tune the band gap of molybdenum-doped Bi₂WO₆ (Mo-Bi₂WO₆) by an amalgamation of conducting polymer nanofibers for efficient hydrogen generation via photocatalytic water splitting. The heterostructures mimic natural photosynthetic systems via S-scheme charge transfer, utilizing the conducting polymer component to harvest photons for reduction reaction and the transition metal part to hasten catalytic activities by facile charge transfer, which drastically lowers the transport resistance, as reflected in impedance spectra. The optimal content of 2 wt % Mo-BiWO₆ as a cocatalyst in the heterostructures reaches a remarkable H₂ production rate of 131 mmol g^–1 h^–1 with an 18% higher apparent quantum efficiency than pure PPy. Moreover, the heterostructure displays 200- fold higher photocurrent density with fortuitous photostability. The presence of PPy efficiently suppresses charge recombination of Mo-Bi₂WO₆ and improves interfacial charge transfer at the heterostructure. The dominant factor for higher photocatalytic activity is proposed based on a femtosecond transient absorption spectra study supported further by time-resolved photoluminescence spectra and valence band X-ray photoelectron spectroscopy. This work provides a facile approach to developing high-performance, noble-metal-free visible light-driven photocatalysts for efficient solar-fuel production.