Fig. 4

Catalytic activity and density functional theory (DFT) calculations. a Photographs of the ca.1.0 kg of CASFZU-1 prepared in the laboratory. b Scheme for cycloaddition of CO₂ with epoxides to produce cyclic carbonates catalysed by CASFZU-1. c The amount of CO₂ fixation with 2-methyloxirane by chemical conversion reactions catalysed by 1 g of different MOFs in 24 h. From left to right, the columns represent MOF crystals of pristine HKUST-1, CASFZU-1 and random-etching MOFs, HKUST-1 nanosheet and collapsed MOF forms. Error bars represent the standard deviation of three replicate samples. d Conversion for cycloaddition of CO₂ with the six epoxides catalysed by HKUST-1 (grey), random-etching MOFs (light blue) and CASFZU-1 (red) after normalising BET. Columns from left to right represent 2-methyloxirane; 2-ethyloxirane; 2-(chloromethyl)oxirane; 2-(bromomethyl)oxirane; 2-octyloxirane; and 1, 2-epoxydodecane. e Turnover frequency (TOF) comparison of CASFZU-1 with the other catalysts in representative publications on catalysis of the cycloaddition reaction of CO₂ with 2-methyloxirane, 2-ethyloxirane and 1,2-epoxydodecane (see Supplementary Tables 7–9 for details). The rightmost red columns represent CASFZU-1. f The computed reaction energy profiles of the CO₂ fixation reaction on HKUST-1 and CASFZU-1. TS, transition state. The pathways are divided into five steps: (i) adsorption of epoxy; (ii) epoxy ring opening step; (iii) CO₂ electrophilic attack step; (iv) intramolecular cyclisation step; (v) product desorption (see Supplementary Figures 49, 51 and 52 for more details and references). Colour scheme for chemical representation: cyan, Cu; red, O; grey, C; tangerine, Br; blue, N; white, H