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

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.