Thermal expansion-quench of nickel metal-organic framework into nanosheets for efficient visible light CO2 reduction

Metal-organic framework nanosheets (MOF NNs) offer potential opportunities for many applications, but an efficient strategy for the scalable preparation of few-layered two-dimensional (2D) MOF NNs are still a major challenge. Herein, we present an efficient top-down method for the synthesis of the Ni-BDC (Ni 2 (OH) 2 (1,4-BDC); 1,4-BDC = 1,4-benzenedicarboxylate) nanosheets utilizing a novel thermal expansion-quench method of the flowerlike bulky MOFs in liquid N 2 . The obtained Ni-BDC nanosheets exhibit significantly enhanced photocatalytic performance of reductive CO 2 deoxygenation (7.0 μmol h −1 mg −1 ) under visible light illumination compared with the bulky MOFs, due to much higher surface area for CO 2 adsorption, more abundant active sites exposed and stronger electron transport ability of the nanosheets. More importantly, this synthetic strategy can be extended to fabricate other MOF nanosheets which also exhibit significantly improved performance for deoxygenative CO 2 reduction compared to their bulky counterparts. This work may provide a guideline for preparing other 2D layered photocatalysts materials to realize energy conversion applications. Nickel metal-organic frameworks (MOF) Ni-BDC nanosheets (Ni-BDC NNs) have been successfully synthesized by an efficient, top-down thermal expansion-quench method. The unique structures with large surface are a exposing abundant active sites, contribute an improved CO 2 photoreduction.