Bimetallic Ni–Zn MOF Decorated with Carbon Dots for Visible-Light-Driven Reductive Amination of Glycerol to Alanine

Abstract

The sustainable conversion of renewable biomass into high-value amino acids is a key objective of green chemistry. In this work, a bimetallic Ni–Zn MOF was synthesized using a solvothermal approach and is subsequently postfunctionalized with biomass-derived Carbon Dots (CDs) to fabricate a photoactive CD@Ni–Zn MOF nanocomposite. The structural and physicochemical properties of the materials were characterized using FTIR, TGA, XRD, BET, XPS, HRTEM, SAED, FESEM, EDAX, DLS, and elemental mapping techniques. The CD@Ni–Zn MOF nanocomposite exhibits enhanced photocatalytic performance in the reductive amination of glycerol to alanine, achieving > 99% selectivity within 6 h under optimized conditions. The formation of alanine was confirmed by ninhydrin assay, 1H and 13C NMR spectroscopy, solid-state FTIR, CD spectroscopy, and mass spectrometry. The enhanced catalytic activity of the composite is attributed to the incorporation of CDs, which effectively reduce the band gap, improve visible-light absorption, and facilitate efficient photoinduced charge separation. Furthermore, density functional theory calculations and in situ ATR-IR studies provided insights into the reaction mechanism and key intermediates. The catalyst demonstrated excellent stability and recyclability, highlighting its potential for efficient and sustainable biomass valorization.