Surface defect-induced electronic structures of lead-free Cs2AgBiBr6 double-perovskite for efficiently solar-driven photocatalytic performance

Abstract

Lead-free Cs2AgBiBr6 double-perovskite has triggered appealing interest in various solar energy-related applications including solar devices and photocatalysis. Nevertheless, further development of the perovskite materials is restricted due to their low redox capacity of the energy band, which is determined by the intrinsic electronic structure. Herein, we demonstrate surface defect-induced electronic structures of the Cs2AgBiBr6 for achieving efficient photocatalytic performance by simply controlling the nucleation and growth processes of the lead-free double-perovskite. During the synthesis process, the strong interaction between the chelating agent EDTA and Cs+ ion leads to the generation of Cs vacancies of Cs2AgBiBr6, which promotes the formation of surface defects to control the electronic structure of double perovskite. The optimized Cs2AgBiBr6 has the strongest reduction capacity with the conduction band potential of −1.53 V (vs NHE at pH = 7) so far, which can greatly promote the production of superoxide radicals (O2–), improving the photocatalytic efficiency of the Cs2AgBiBr6. Under one simulated sunlight irradiation, the photodegradation efficiency of tetracycline (TC) for the as-obtained Cs2AgBiBr6 with surface defect is up to 81.8 % within 90 min. Environmental ImplicationEnvironmental pollution resulting from various factitious and industrial activities is primarily composed of organic compounds such as pesticides, dyes, antibiotic and so on. Antibiotic, difficult to decompose, can only be decomposed slowly by chemical or biological methods owing to their strong stability. Photocatalysis is emerging as a promising technology for environmental remediation because of its strong oxidation ability and fast reaction rate. The eco-friendly Cs2AgBiBr6 perovskite with a suitable bandgap (1.83 eV ∼ 2.19 eV) has recently emerged as a promising photocatalyst for application in pollutant degradation.