Acidification of potassium bismuthate for enhanced visible-light photocatalytic degradation ability: An effective strategy for regulating the abilities of adsorption, oxidation, and photocatalysis

Abstract

In this work, a facile and effective strategy for improving the degradation ability of potassium bismuthate (KBiO3) was first proposed by using HNO3 acidification. The degradation ability of methylene blue (MB) by untreated and acidified KBiO3 was systematically investigated under both dark and light conditions. Under light condition, KBiO3 exhibited physical adsorption, chemical oxidation, and photocatalysis abilities during the MB degradation. Compared with KBiO3-0, the apparent reaction rate constant of KBiO3-1.0 (c(HNO3)/c(KBiO3) = 1.0) increased by 7.04 times. The specific surface area increased by 2.94 times. In-situ EPR demonstrated that the generation of singlet oxygen (1O2) was gradually increased with increasing acid addition, which promoted the oxidation degradation of MB. Moreover, according to the photocurrent, EIS, and PL spectra measurements, the separation efficiency of photogenerated electrons and holes was significantly enhanced, indicating the improved photocatalysis ability of KBiO3. This work provides a deep understanding into the regulation of adsorption, oxidation, and photocatalysis abilities of bismuthate.