Lead Halide Perovskite Cube Coupled Star Nanocrystal Photocatalysts

Abstract

Ligand dynamics on the surface of nanocrystals plays a major role in controlling their successive layers growth. This has been widely established for chalcogenide nanomaterials but less explored for recently emerged halide perovskite nanocrystals. However, with the introduction of different non-lead metal (Cd and Mn) acetates/oxides to limit surface halide concentration and alkylammonium ion ligands, herein, star shaped cube coupled nanocrystals are reported, and their growth from less than 50 nm to nearly 500 nm is monitored. These acetates/oxides helped in inducing secondary growth along one of the {200} facets of parent orthorhombic CsPbBr3 cube nanocrystals and led to the unique star shaped nanocrystals which consumed smaller size cube nanocrystals and continued to grow further. The method is also extended to CsPbCl3 nanocrystals. Due to complex shapes, these are further explored as photocatalysts for CH4 and CO evolution under purging CO2 gas in ethyl acetate/water medium, and their catalytic activities are compared with cube nanocrystals.

Efficient Exciton Dissociation through the Edge Interfacial State in Metal Halide Perovskite-Based Photocatalysts

“…The experiment is conducted in a well-established ethyl acetate/water system under visible-light irradiation (λ > 420 nm), where ethyl acetate serves as the CO 2 solvent to stabilize CPB and the trace water provides the protons (details in Supporting Information Methods). , As expected, CPB/TMC-X shows obviously enhanced activity as compared to bare CPB. Particularly, as shown in Figure S9, CPB/TMC-150 stands out among others with the highest electron-consumption rate, i.e., 33.23 μmol g –1 h –1 , which is more than double that for bare CPB (i.e., 16.16 μmol g –1 h –1 ).…”

“…29 Although the ethyl acetate/water system is under debate, still most of the generated CO and CH 4 are widely accepted as the products of CO 2 reduction. 28 To further elucidate the origin of the products, a 13 CO 2 -labeling experiment is carried out by using synchrotron-radiation vacuum-UV photoionization mass spectrometry (SVUV-PIMS). When 13 CO 2 is used as the feedstock, CPB/TMC-150 produces a significant amount of 13 CO (m/z = 29) while no 13 CH 4 (m/z = 17) signal is detected (Figure S10), which not only confirms that the evolved CO indeed originates mainly from the photocatalytic CO 2 reduction but further evidences the aforementioned nearly 100% selectivity.…”

“…It is noteworthy that such a performance is superior to the very recently reported cesium lead halide/TiO 2 system that exhibits a CO-evolution rate of 9.02 μmol g –1 h –1 with a selectivity of 95% . Although the ethyl acetate/water system is under debate, still most of the generated CO and CH 4 are widely accepted as the products of CO 2 reduction . To further elucidate the origin of the products, a 13 CO 2 -labeling experiment is carried out by using synchrotron-radiation vacuum-UV photoionization mass spectrometry (SVUV-PIMS).…”

Facets-Directed Epitaxially Grown Lead Halide Perovskite-Sulfobromide Nanocrystal Heterostructures and Their Improved Photocatalytic Activity

“…Lead halide perovskite nanocrystal heterostructures remain one of the most aspirant optical materials in current research because of the possibility of enhancing their charge carrier transportation in devices and also imparting phase and/or optical stability compared to the parent perovskite nanocrystals. − In spite of extensive research in developing bright and color tunable emissions from different halide perovskite nanocrystals, − the heterostructures of any of their combinations are limited. While shapes have been tuned, sizes can be varied, growths have been controlled, phase and optical stability have been understood, and surface-ligand chemistry has also been investigated, − the hetero-epitaxial growth of other material or even same halide perovskite nanocrystals on preformed or parent perovskite nanocrystals could not be successfully achieved yet. Even a second-layer growth or shelling of another or the same material on seed nanocrystals also could not be carried out in spite of the large successes achieved in understanding the chemistry of formation of these nanocrystals. , Most of such reports on all-inorganic heterostructures involve non-epitaxial or random deposition of secondary materials without giving a proper chemistry of the growth of one on the surface of another material. − ,− Hence, designing epitaxial heterostructures of lead halide perovskites remained timely important to boost their charge carrier transport activity and also shelling with different materials to induce long-term ambient stability.…”

Halide Perovskite Cluster Precursors: A Paradigm for Obtaining Structure- and Color-Tunable Light-Emitting Nanocrystals

“…76 Moreover, this different type of oriented attachments of nanocrystals might exhibit differences in carrier transportation or other optoelectronic properties. Going beyond the polyhedral structures, a recent report by Bera et al 90 described the formation of a complex star-like structure of CsPbBr 3 by secondary injection of the clusters into a Cd stock solution, and this structure showed superior photocatalytic activities. These findings clearly support the fact that this cluster-mediated approach helps in obtaining new and more complex perovskite structures.…”