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Perovskite metal halides have attracted extensive attention because of their excellent photoelectric properties and structural adjustability. Herein, the authors report a facile method for the controlled synthesis of cesium‐bismuth halides by controlling the stoichiometry of Cs/Bi precursors at room temperature. The 0D Cs3BiCl6 and 1D Cs3Bi2Cl9 can be obtained at the Cs/Bi feed ratio of 3:1 and 3:2, respectively. Though both metal halides exhibit a very low photoluminescence quantum yield (PLQY) due to their intrinsic nature of indirect band gaps, they exhibited bright orange broadband emission after Mn2+ doping. Combining density functional theory (DFT) calculations, it is found that an appropriate amount of Mn2+ doping does not change the crystal structures of cesium‐bismuth halides, but Mn 3d orbitals produce impurity states in the forbidden energy gaps of the host structures, resulting in efficient energy transfer from the conduction band of the host to d‐state of Mn ions. Importantly, the reversible structural switch of Mn‐doped Cs3BiCl6 and Cs3Bi2Cl9 metal halides can be flexibly adjusted through the post addition of the CsCl/BiCl3 precursors. These results tremendously enrich the synthetic chemistry of low‐dimensional metal halides and provide a beneficial reference for the regulation of crystal structure and optical properties of metal halides.

Lead halide perovskites have demonstrated promising emission tunability achieved by composition engineering, which makes them viable in several potential applications. Determining how to effectively control the crystalline structural transformation and composition in lead‐free halide perovskites is of great importance. Herein, a controllable synthetic method is reported to obtain the 0D metal halide perovskite derivatives (Cs1−xRbx)2InCl5∙H2O and (Cs1−xRbx)3InCl6, through synergistic regulation of the Cs/Rb feed ratios and the reaction solvent. When hydrochloric acid (HCl) is used as the reaction solvent, (Cs1−xRbx)2InCl5∙H2O is obtained at a high Cs/Rb feed ratio greater than 2:1, while (Cs1−xRbx)3InCl6 is obtained at a low Cs/Rb feed ratio of less than 2:5. However, when anhydrous methanol (MeOH) is used as the reaction solvent, only the (Cs1−xRbx)3InCl6 structure is obtained at all Cs/Rb feed ratios. In addition, a reversible crystalline structural transformation is demonstrated between (Cs0.67Rb0.33)2InCl5∙H2O and (Cs0.67Rb0.33)3InCl6 by immersing the as‐prepared products into MeOH and HCl sequentially, which generates a novel green/yellow reversible emission switch. The Sb3+ ion self‐trapped exciton emission and stability of the synthesized (Cs1−xRbx)2InCl5∙H2O and (Cs1−xRbx)3InCl6 are systematically investigated. The results are helpful for promoting the diverse photonics and optoelectronics applications of these environmentally stable perovskite derivatives.

Targeting tumor hydrogen peroxide (H2O2) with catalytic materials has provided a novel chemotherapy strategy against solid tumors. Because numerous materials have been fabricated so far, there is an urgent need for an efficient in silico method, which can automatically screen out appropriate candidates from materials libraries for further therapeutic evaluation. In this work, adsorption‐energy‐based descriptors and criteria are developed for the catalase‐like activities of materials surfaces. The result enables a comprehensive prediction of H2O2‐targeted catalytic activities of materials by density functional theory (DFT) calculations. To expedite the prediction, machine learning models, which efficiently calculate the adsorption energies for 2D materials without DFT, are further developed. The finally obtained method takes advantage of both interpretability of physics model and high efficiency of machine learning. It provides an efficient approach for in silico screening of 2D materials toward tumor catalytic therapy, and it will greatly promote the development of catalytic nanomaterials for medical applications.