Ultra-thin Two-Dimensional Trimetallic Metal–Organic Framework for Photocatalytic Reduction of CO2

Photocatalytic reduction of carbon dioxide (CO2) into high-value chemicals is a very effective way to solve the greenhouse effect, improve the utilization ratio of resources, and cope with the energy crisis. However, the low catalytic activity and poor product selectivity of the catalyst have been largely restricting its large-scale application. Herein, we successfully synthesized an ultra-thin two-dimensional trimetallic metal–organic framework (NiZrCu-BDC) nanosheet as a photocatalyst for CO2 reduction, and the average thickness of NiZrCu-BDC is about 4 nm. The NiZrCu-BDC nanosheet has the ability to reduce CO2 to methanol (41.05 μmol h–1 g–1) and ethanol (36.62 μmol h–1 g–1), and the turnover frequency of NiZrCu-BDC is 34 times more than that of NiZr-BDC. Zr and Cu doping enables enrichment of Ni surface charges to promote CO2 chemisorption, and the ultra-thin structure can shorten the electron transport path. Meanwhile, the electron density of Ni catalytical sites in NiZrCu-BDC is enhanced by doping Cu and Zr to facilitate COOH* and CHO formation, which are deemed as key species for CO2 reduction reactions to liquid products. This work provides further insights into the photocatalytic reduction of CO2 based on the multi-metal–organic framework.