Cyclodextrins grafted MoS2/g-C3N4 as high-performance photocatalysts for the removal of glyphosate and Cr (VI) from simulated agricultural runoff

Abstract

The hydrophobicity of MoS2/g-C3N4 based photocatalysts remains a major hurdle to their successful application for the remediation of water-soluble contaminants such as herbicides and heavy metals. Herein, we develop new photocatalysts based on the graft of three different cyclodextrins (α-CD, β-CD and γ-CD) on MoS2/g-C3N4 composites (CDs/MoS2/g-C3N4) for the removal of glyphosate and Cr (VI) from simulated agricultural runoff. CDs/MoS2/g-C3N4 show remarkably enhanced photocatalytic activities for glyphosate degradation and Cr (VI) reduction compared to pristine MoS2/g-C3N4. In addition, γ-CD/MoS2/g-C3N4 exhibits the highest hydrophilicity and photocatalytic activity among these three different cyclodextrins grafted MoS2/g-C3N4. The mechanistic investigation indicates that cyclodextrins can not only increase the accumulation of glyphosate and Cr (VI) onto the surface of CDs/MoS2/g-C3N4 but also facilitate the fleet separation of photo-induced electron-hole pairs. In summary, these results collectively imply that the graft of cyclodextrins could be an effective strategy to improve the photocatalytic efficiency of MoS2/g-C3N4 composites for the removal of glyphosate and Cr (VI) from simulated agricultural runoff.