Synthesis of Layered Lead-Free Perovskite Nanocrystals with Precise Size and Shape Control and Their Photocatalytic Activity

Halide perovskites have attracted enormous attentiondue to theirpotential applications in optoelectronics and photocatalysis. However,concerns over their instability, toxicity, and unsatisfactory efficiencyhave necessitated the development of lead-free all-inorganic halideperovskites. A major challenge in designing efficient halide perovskitesfor practical applications is the lack of effective methods for producingnanocrystals with precise size and shape control. In this work, alayered perovskite, Cs4ZnSb2Cl12 (CZS),is found from calculations to exhibit size- and facet-dependent optoelectronicproperties in the nanoscale, and thus, a colloidal method is usedto synthesize the CZS nanoparticles with size-tunable morphologies:zero- (nanodots), one- (nanowires and nanorods), two- (nanoplates),and three-dimensional (nanopolyhedra). The growth kinetics of theCZS nanostructures, along with the effects of surface ligands, reactiontemperature, and time were investigated. The optoelectronic propertiesof the nanocrystals varied with size due to quantum confinement effectsand with shape due to anisotropy within the crystals and the exposureof specific facets. These properties could be modulated to enhancethe visible-light photocatalytic performance for toluene oxidation.In particular, the 9.7 nm CZS nanoplates displayed a toluene to benzaldehydeconversion rate of 1893 & mu;mol g(-1) h(-1) (95% selectivity), 500 times higher than the bulk synthesized CZS,and comparable with the reported photocatalysts. This study demonstratesthe integration of theoretical calculations and synthesis, revealingan approach to the design and fabrication of novel, high-performancecolloidal perovskite nanocrystals for optoelectronic and photocatalyticapplications.

Automated summary

This study synthesized CZS nanoparticles with adjustable size and morphology through colloidal method. The optoelectronic properties of CZS nanocrystals varied with size and shape, and could be modulated to improve the photocatalytic performance. This research demonstrates a new approach to the design and fabrication of high-performance perovskite nanocrystals for optoelectronic and photocatalytic applications.