Two birds with one stone: Facile fabrication of a ternary ZnIn₂S₄/BiVO₄/MWCNTs nanocomposite for photocatalytic detoxification of priority organic pollutants and hydrogen production with a proposed mechanism

A series of ternary nanocomposites with different weight percentages of zinc indium sulfide, bismuth vanadate, and multiwalled carbon nanotubes (ZnIn₂S₄/BiVO₄/MWCNTs) were synthesized using a simple thermal impregnation method to obtain high charge separation and transfer efficiency, thus improving their photocatalytic performance. The 20 wt% ZnIn₂S₄/BiVO₄/MWCNTs (20 wt% ZBM) nanocomposite exhibited enhanced photocatalytic activity compared to pure BiVO₄ and ZnIn₂S₄ for the degradation of methylene blue, acetaminophen, and allopurinol in an aqueous solution when exposed to a visible light source and atmospheric oxygen. This nanocomposite demonstrated a particularly high degradation rate constant (k = 6.39 × 10⁻² min⁻¹) for the photocatalytic degradation of methylene blue. The introduction of MWCNTs boosted the photocatalytic performance of the 20 wt% ZBM nanocomposite, attaining a maximum H₂ production of 1704 μmol g⁻¹. Repeated photocatalytic H₂ generation reached 1621 μmol g⁻¹ after 5 h of irradiation with four consecutive cycles. Therefore, we propose a “two birds with one stone” strategy for greatly improved photocatalytic wastewater detoxification and H₂ production by prolonging the lifetime of the photogenerated electron–hole pair separation.