Construction of visible light active CuS/MoS2 heterojunctions for heightened photoreduction of Cr(VI)

CuS/MoS₂ heterojunctions were fabricated by a facile one-step hydrothermal method and evaluated via the photoreduction of Cr(VI) under visible light irradiation. The CuS/MoS₂ heterojunctions demonstrated a hierarchical porous structure, self-assembled from intersecting thin nanosheets, which resulted in a flower-like morphology. The optimized CuS/MoS₂ heterojunction (CuS/MoS₂-4.6) exhibited superior photocatalytic performance toward the removal of Cr(VI) under visible light with a k value of 1.33 × 10⁻² min⁻¹, which was much higher than that of pure CuS (2.13 × 10⁻⁴ min⁻¹) and MoS₂ (4.39 × 10⁻⁴ min⁻¹). The enhanced Cr(VI) photoreduction performance was ascribed to the construction of a type II CuS/MoS₂ heterojunction, in which electrons in the conduction band (CB) of CuS were transferred to the CB of MoS₂ due to the favorable band alignment, while holes in the valence band (VB) of MoS₂ flowed to the VB of CuS. This led to the efficient spatial separation and transfer of electrons and holes, inhibiting the recombination of photogenerated carriers, thus boosting the remarkable photocatalytic activity. This work provides a prospective heterojunction catalyst for photoreduction of Cr(VI).