Lead-free and highly-stable double perovskite Cs2SnClXI6-X microcrystals for efficient photocatalytic degradation

Abstract

In order to protect water bodies and prevent water pollution, the direct use of clean solar energy to degrade the organic dyes in industrial wastewater into innoxious products is a potential strategy and a trending topic. Recently, the lead halide perovskites have been intensively investigated as photocatalysts on account of their unique photoelectric properties. Unsatisfactorily, the lead toxicity and instability of these materials cause irreversible harm to the ecology and low long-term degradation efficiency, limiting their practical applications. For the first time, lead-free double perovskite Cs2SnClXI6-X microcrystals were prepared by solution supersaturation recrystallization method for the photocatalytic degradation of Sudan Red III. The optical band gaps of the Cs2SnClXI6-X microcrystals were adjustable from 4.48 to 1.34 eV upon halogen regulation, while the photodegradation performance of Cs2SnCl4.1I1.9 was even much higher than the recently reported composite photocatalysts under similar conditions. Furthermore, the recycling and storage experiments demonstrated the reusability and excellent environmental stability of the as prepared Cs2SnClXI6-X microcrystals. Based on the results of the free radical trapping tests and electron paramagnetic resonance measurements, the mechanism for the photocatalytic degradation process were discussed in details.