Facile anion exchange to construct uniform AgX (X = Cl, Br, I)/Ag2CrO4 NR hybrids for efficient visible light driven photocatalytic activity

Abstract

Herein, uniform AgX/Ag2CrO4 (X = Cl, Br, I) NR hybrids were successfully prepared by a facile in-situ anion exchange reaction at room temperature. When AgX was formed on the surface of Ag2CrO4 NRs, the light absorption range AgX/Ag2CrO4 hybrids show apparent red shifting by compared with the pure Ag2CrO4 NRs, which indicates the enhanced ability of utilizing solar energy. Moreover, the as-prepared AgBr/Ag2CrO4 NR hybrids exhibit the highest photocatalytic activity for degradation of phenol under visible light irradiation owing to more suitable band offset between AgBr and Ag2CrO4 to form type-II heterojunction in comparison with the other two hybrids with type-I heterojunction. The kinetic constant over AgBr/Ag2CrO4 NR hybrids is 4 times as high as the pure Ag2CrO4 NRs, which demonstrates that the formation of heterojunction is beneficial for suppressing the recombination of photogenerated holes and electrons. Moreover, the radO2− and h+ are proven to be main active species involving in the photocatalytic degradation of phenol. Apart from that, chlorine radicals are found to be produced simultaneously to enhance photocatalytic activity of AgCl/Ag2CrO4.