Facile synthesis of a novel AgIO3/BiVO4 photocatalyst with two-step charge separation to enhance visible-light-driven photocatalytic performance for carbamazepine degradation

Abstract

• A novel visible-light-driven AgIO 3 /BiVO 4 photocatalyst was fabricated. • The two-step charges separation in AgIO 3 /BiVO 4 enhanced the photocatalytic activity. • The different crystal facets in decahedral BiVO 4 facilitated the charges spatial pre-separation. Rapid recombination of photo-generated electron-hole in photocatalyst limits the improvement in photocatalytic activity. A novel visible-light-driven AgIO 3 /BiVO 4 photocatalyst with two-step charge separation enhancing photocatalytic activity was fabricated. The composite with optimum molar ratio of 40% AgIO 3 to BiVO 4 has a narrow band gap of 2.28 eV, which is smaller than that of BiVO 4 (2.41 eV). The composite presented 99.38% degradation efficiency of rhodamine B in 40 min under visible light irradiation, which is higher than 1% and 9% degradation efficiencies by BiVO 4 and AgIO 3 , respectively. In addition, a 97.86% degradation efficiency of carbamazepine was achieved in 60 min. Thus, the significant enhancement of photocatalytic activity depended on the two-step charge separation in AgIO 3 /BiVO 4 . The first step was the spatial pre-separation among different crystal facets in decahedral BiVO 4 . Photo-generated electrons accumulated on {0 1 0} facets. Moreover, photo-generated holes on {1 1 0} facets facilitated the production of •OH radicals. The second separation was achieved by the type Ⅱ heterojunction structure of AgIO 3 /BiVO 4 . Photo-generated electrons in conduction band were transferred from BiVO 4 {0 1 0} facets to AgIO 3 , and holes in valence band accumulated on BiVO 4 {1 1 0} facets. This work provides an effective method to further decrease electron-hole recombination in photocatalysts and promote their environmental application in contaminated water purification.