Phase Transformation of Colloidal Cs₃Cu₂Cl₅ Nanocrystals to CsMCl (M = Zn, Bi, Cd) by Cation Exchange and Their Thermodynamic Study by Density Functional Theory Calculations

Abstract

We present the phase transformation from colloidal Cs 3 Cu 2 Cl 5 nanocrystals to CsMCl (M = Zn, Bi, Cd) by cation exchange reaction. Cs 2 ZnCl 4 , Cs 3 BiCl 6 , and CsCdCl 3 were successfully synthesized, and the feasibility of phase transformations was demonstrated using density functional theory calculations, which revealed the high thermodynamic stability of the three structures.The results indicate that these structures can be synthetically prepared. The difference in reactivity between Zn, Bi, and Cd cations, which was verified by changing the reaction temperatures, was demonstrated using chemical softness calculations considering the interactions between Cl − and three cations. Additionally, for each cation exchange reaction, thermodynamic stability, estimated in terms of the formation energy, contributed to reactivity. The Cs 2 ZnCl 4 structure required the mildest reaction condition (i.e., 110 °C). As a reverse reaction, Cu cations were added to solutions of Cs 2 ZnCl 4 , Cs 3 BiCl 6 , and CsCdCl 3 , and CsCu 2 Cl 3 was obtained instead of Cs 3 Cu 2 Cl 5 . The mechanism was not cation exchange, and transmission electron microscopy data showed that nanoparticles were used as precursors for forming CsCu 2 Cl 3 particles.

Dual-Mode Luminous Lead-Free Cs3Cu2Cl5 Perovskite Embedded in UiO-66-NDC Nanoparticles for Multilevel Anti-Counterfeiting

“…All the corresponding elements were detected for the pure Cs 3 Cu 2 Cl 5 NCs and UiO-66-NDC. Similarly, for CCL 4 /UiO nanocomposites, the signals observed at 284.2, 530.9, 182.1, 724.2, 934.2, and 198.4 eV (FigureS6) are attributed to C 1s, O 1s, Zr 3d 2/5 , Cs 3d, Cu 2p, and Cl 2p, respectively, which is consistent with the existence of Cs 3 Cu 2 Cl 5 NCs in nanocomposites 33,36.…”

“…Black dots with an average size of 5–7 nm were observed to be embedded in the UiO-66 matrix (Figures b 1 and S1c). The insert of b 2 is the high-resolution TEM (HRTEM) image of Cs 3 Cu 2 Cl 5 , with a marked interplanar spacing of 0.234 nm, which is consistent with the (223) plane of orthorhombic structure of Cs 3 Cu 2 Cl 5 . However, the average size of Cs 3 Cu 2 Cl 5 NCs (5–7 nm) within UiO-66-NDC was significantly smaller than those of the free Cs 3 Cu 2 Cl 5 NCs (50–70 nm), which is attributed to the nanoconfinement effects .…”

“…The diffraction peaks of the Cs 3 Cu 2 Cl 5 NCs accurately matched the standard card (ICSD No. 024-0247) of the orthorhombic structure. , Meanwhile, the diffraction signals of (202), (222), (105), (224), and (402) planes also attributed to the Cs 3 Cu 2 Cl 5 NCs were observed in the CCL 4 /UiO nanocomposite, suggesting the presence of highly crystallized states of Cs 3 Cu 2 Cl 5 NCs in UiO-66-NDC. Therefore, the corresponding diffraction signals of both UiO-66-NDC and Cs 3 Cu 2 Cl 5 NCs were observed in the CCL 4 /UiO nanocomposite.…”

“…Transmission electron microscopy (TEM) and scanning electron microscopy (SEM) were performed to provide direct evidence for the encapsulation of Cs 33 However, the average size of Cs 3 Cu 2 Cl 5 NCs (5−7 nm) within UiO-66-NDC was significantly smaller than those of the free Cs 3 Cu 2 Cl 5 NCs (50−70 nm), which is attributed to the nanoconfinement effects. 34 TEM showed that the average pore size of UiO-66-NDC was 5−8 nm (Figure S5b), which is in perfect agreement with the average size of the Cs 3 Cu 2 Cl 5 NCs in UiO-66-NDC.…”