Photocatalytic reduction of CO2 in aqueous phase using amino-functionalized MOFs loaded with hydroxy-functionalized graphene quantum dots

Hydroxy-functionalized graphene quantum dots (OH-GQDs) were loaded onto NH2-MIL-101(Fe) to prepare a novel binary OH-GQDs/NH2-MIL-101(Fe) (OGNM) composite with a simple solvothermal method. The obtained catalysts were characterized by SEM, TEM, XRD, FI-IR, XPS and BET to analyze the morphology, elemental composition, and specific surface area of the composite material. Notably, the morphology and micro-structures of OGMM-3 exhibited that OH-GQDs evenly dispersed on the surface of hexagonal micropillar NH2-MIL-101(Fe). The nanocomposite catalysts were tested in a photocatalytic CO2 reduction system using water and acetonitrile as solvents, without additional sacrificial agents. OGNM-3 composite possessed the optimum photoreduction CO2 activity, with a CO yield of 128.68 mu mol.g- 1 within 10 h, which was 5.3 times higher than that of pure NH2-MIL-101(Fe). After three cycles of reuse, the catalyst still maintained catalytic activity without any significant changes in its crystal structure, morphology or functional groups. In summary, this study proposed a design for synthesizing binary OGNM photocatalysts, offering useful insights for cost-effectively address CO2 emissions in greenhouse gas emissions.