Novel p–n heterojunction photocatalyst constructed by porous graphite-like C3N4 and nanostructured BiOI: facile synthesis and enhanced photocatalytic activity

Abstract

In this work, n-type porous graphite-like C₃N₄ (denoted as p-g-C₃N₄) was fabricated and modified with p-type nanostructured BiOI to form a novel BiOI/p-g-C₃N₄ p–n heterojunction photocatalyst for the efficient photocatalytic degradation of methylene blue (MB). The results show that the BiOI/p-g-C₃N₄ heterojunction photocatalyst exhibits superior photocatalytic activity compared to pure BiOI and p-g-C₃N₄. The visible-light photocatalytic activity enhancement of BiOI/p-g-C₃N₄ heterostructures could be attributed to its strong absorption in the visible region and low recombination rate of the electron–hole pairs because of the heterojunction formed between BiOI and p-g-C₃N₄. It was also found that the photodegradation of MB molecules is mainly attributed to the oxidation action of the generated O₂˙⁻ radicals and partly to the action of h_vb ⁺via direct hole oxidation process.