Z-scheme driven photocatalytic activity of CNTs-integrated Bi2S3/WO3 nanohybrid catalysts for highly efficient hydrogen evolution under solar light irradiation

Abstract

Harvesting solar energy for the production of molecular hydrogen through photocatalytic approach is a clean and sustainable pathway to deal with the energy crisis and pollution. In this connection, direct Z-scheme interfaced noble metal free CNTs integrated Bi2S3-WO3 ternary composite was designed and developed through simple hydrothermal and wet impregnation strategies. This combination was manifested for the first time to tackle the photo-corrosion of Bi2S3 through Z-scheme heterojunction formation, and its effective contribution in the mitigation of charge carrier recombination was investigated. 9 wt% WO3 loaded Bi2S3 (WB-9) delivered a notable H2 production rate of 4.85 mmol.h-1.g-1cat over 5 vol% glycerol as a sacrificial reagent under simulated solar light irradiation. This enhancement was six folds higher than the pristine Bi2S3 photocatalytic activity. To enhance the reduction half-reaction further, electron mobility was regulated with CNT integration, which not only triggers the successive transport of electrons through its tubular channel, but also facilitate an excellent reduction co-catalyst to support rapid reduction of protons to form H2 molecules. Upon optimization of CNTs loading, 1 wt % CNTs loaded WB-9 (CWB-4) produced two-folds higher H2 production rates than WB-9, which is about 9.91 mmol.h 1. g � 1 cat. The observed efficiency, stability, and recyclability of CWB-4 attributed to the effective utili-zation of generated charge carriers across the system and suppressed photo-corrosion of Bi2S3 through the Z-scheme interface.