Crucial Role of Water in the Mechanosynthesis of CsPbI₃ and Other ABX₃ Halides

Abstract

Mechanochemical synthesis of CsPbI 3 ,a sa model system for ABX 3 halides, was studied.W ater was shown to strongly promote the kinetics of formation of CsPbI 3 from the CsI + PbI 2 mixture through increased mobility of the constituting ionic species.S ince many binary and ternary halides are hygroscopic, it was concluded that the presence of small, uncontrollable and unintentional additions of water should often occur in both precursor mixtures and synthesized complex halides boostingthe kinetics of formation of many,i fn ot all,t ernaryo rganic-inorganich ybrid halides such as, for example, MAPbX 3 (X = Cl, Br,I). In addition, trace amounts of water should influence the transport characteristics of complex halides. Thus, the presence of water explains, at least partially,t he huge scatter in both the reported mechanochemical reaction times necessary for obtaining single-phaseAPbX 3 perovskite halidesa nd the activation energies of ionic diffusion in APbX 3 .

Sustainability Assessment of Mechanochemistry by Using the Twelve Principles of Green Chemistry

“…[99] Moreover, in situ released liquid products in mechanochemical transformations have been observed to accelerate chemical reactions, [100] thus indicating the possibility for LAG catalysis (Figure 4c). [101] Notably, LAG has also enabled the establishment of practical and economic isotope labelling protocols. [102][103][104][105] But not only liquids have been used as auxiliaries in ball milling reactions, the addition of catalytic amounts of solid ionic salts has also been a common practice.…”

“…Additionally, it has been reported that LAG can exert inhibitive or prohibitive effects on the formation of molecular crystals by mechanochemistry [99] . Moreover, in situ released liquid products in mechanochemical transformations have been observed to accelerate chemical reactions, [100] thus indicating the possibility for LAG catalysis (Figure 4c) [101] . Notably, LAG has also enabled the establishment of practical and economic isotope labelling protocols [102–105] …”