Lead-free Rudorffite-type Cs3Bi2Br9 nanoparticles for photocatalytic degradation of rhodamine B and methylene blue

Herein we report the use of Rudorffite-type Cs3Bi2Br9 nanoparticles as a photocatalyst in the degradation of rhodamine B and methylene blue dyes. The synthesis of Cs3Bi2Br9 nanoparticles through the hot-injection method was optimized to a time of 1 min at the temperature of 210 °C. The lead-free nanoparticles were indexed to Cs3Bi2Br9 in a single hexagonal phase with no impurities. The structure of the synthesized nanoparticles was also confirmed with Raman and XPS spectroscopies. The average size and optical bang gap energy of Cs3Bi2Br9 Rudorffite nanoparticles were 17 nm and 2.83 eV, respectively. The cyclic voltammetry technique estimated the electrochemical band-gap of Cs3Bi2Br9 to be 3.01 eV, which is slightly higher than the optical band-gap. The photocatalytic degradation of rhodamine B and methylene blue dyes using Cs3Bi2Br9 nanoparticles at an optimum photocatalyst load of 0.12 g showed the highest photocatalytic degradation of the dyes. The kinetics showed that the rhodamine B dye was degraded faster than the methylene blue. In 100 min degradation time, complete deethylation and demethylation of RhB and MB occurred, respectively.