Modulator-free approach towards missing-cluster defect formation in Zr-based UiO-66

Abstract

Missing-cluster defects in Zr-based UiO-66 can be generated by rigorous control of water without the need of acidic modulators.

An efficient modulated synthesis of zirconium metal–organic framework UiO-66

“…7.4 2q). The crystallite size derived from the (111) reection (FWHM the reection) according to Schaler's formula 33 was almost constant and was independent of the molar ratio HBr/Zr (Fig. 3 and Table S3 †), basically in agreement with the SEM observation (Fig.…”

“…This may be ascribed to the accelerated nucleation of Zr oxoclusters by 40 wt% HBr acid, thus changing the crystallization process from nucleation-limited to growth-limited crystallization. 15,33,34 In addition, UiO-66-2HF and UiO-66-2HCl samples showed similar particle size as UiO-66-HBr samples, indicating the same controlling step (Fig. 3 and Table S3 †).…”

“…2-7 , a broad-peak was additionally observed in the XRD proles of all samples which was assigned to the (110) reo phase or cluster-missing defects. 24,33 Strong acidic modulators (HCl acid, pK a ¼ À8.00; HBr acid, pK a ¼ À9.00; H 2 BDC, pK a1 ¼ 3.51, pK a2 ¼ 4.82) dominate the competition for carboxylate sites on the Zr 6 O 4 (-OH) 4 (CO 2 ) 12 clusters, resulting in samples with a very high concentration of cluster-missing defects. 24 Rel(I) B.P.…”

“…Modulators play important roles in the synthesis of MOFs, such as inuencing crystal morphology, RME and so on. 26,33,40,52 The effect of haloid acid on RMEs of UiO-66 synthesized with 0.2 mol L À1 ZrCl 4 was also investigated and the results were presented in Fig. 9 (Table S1 †).…”

A facile and sustainable one-pot approach to the aqueous and low-temperature PET-to-UiO-66(Zr) upcycling

“…Interestingly, the PXRD pattern of the MOF obtained through PET upcycling appears to be less defective based; on carefully controlling defect concentration and structure it has been noted that missing cluster defects result in notable changes in the diffraction pattern, leading to the prevalence of the Reo phase. 26 While some evidence of the Reo phase can be observed in the pattern of the solvothermally synthesised UiO-66 (Reo(110) at ca. 61), such indication is apparently absent in the PET upcycled sample pattern.…”