Enhanced visible-light-driven reduction of hexavalent chromium under neutral conditions using quasi-MOF photocatalysts via thiocyanate modulation

Abstract

In order to address the issue that the photocatalytic reduction of hexavalent chromium (Cr(VI)) is often limited by the inefficient utilization of electrons in photocatalysts, a quasi-MOF photocatalyst using thiocyanate (—SCN) was developed as a modulator to enhance the charge transfer properties of ZIF-L-based photocatalysts. The incorporation of —SCN introduced structural defects, which improved visible light absorption and the reduction ability of photogenerated electrons. —SCN significantly adjusted the electronic properties and established a stable electron release pathway, serving as active sites for reduction. The optimized quasi-MOF demonstrated a Cr(VI) reduction rate of 94.8% in neutral potassium thiocyanate solution under visible light without a hole scavenger. The reaction rate constant is 2.8 times that of the photocatalyst without defect modulation. This study offers a promising strategy for developing highly efficient photocatalysts for environmental remediation.