Photocatalytic degradation of organic pollutants under visible light using lead-free all-inorganic halide perovskites A3Bi2Cl9 (A = Cs, Rb)

Recently, halide perovskites (HPs) have demonstrated a great potential in light-based technologies. The aim of the research presented in this paper was to explore new possibilities for using lead-free all-inorganic perovskites for photocatalytic applications under visible light irradiation. To this end, we synthesized all-inorganic HPs A3Bi2Cl9 (A = Cs, Rb) via hydrothermal method and investigated their photocatalytic activity under visible light irradiation for water purification. The formation of the HPs was confirmed by XRD, FESEM and EDX analyzes. The optical and electrochemical properties, measured by various techniques such as UV–Vis spectroscopy and Mott-Schottky, confirmed that both Cs3Bi2Cl9 and Rb3Bi2Cl9 are n-type semiconductors with a band gap of 2.72 eV and 3.08 eV, respectively. The photocatalytic performance of the prepared HPs indicated their excellent potential for the removal of organic pollutants. Cs3Bi2Cl9 performed the photocatalytic activity of 100% degradation of Rhodamine B (RhB) and Malachite green (MG) dyes after 100 min and 60 min of visible light irradiation, respectively. Also, Rb3Bi2Cl9 was able to degrade 95% of RhB after 100 min of irradiation. Recycle tests admitted the high stability of the prepared Bi-based perovskites after 4 consecutive cycles of photocatalytic activity.