Construction of 2D/3D BiOI/g-C3N4 S-scheme heterojunction photocatalysts for photocatalytic degradation of organic pollutants

BiOI is a promising photocatalyst due to its exceptional visible light response and high absorption coefficient; however, its performance is hindered by the rapid recombination of electron-hole (e − -h + ) pairs. Herein, a 2D/3D BiOI/g-C 3 N 4 S-scheme heterojunction catalyst was designed and constructed through the alkali etching strategy and subsequent microwave-assisted hydrothermal strategy. The abundant surface active sites and matched band gap of g-C 3 N 4 prepared through alkali etching facilitates anchoring of BiOI nanosheets, contact with contaminants and construction of heterojunctions. 2D/3D S-scheme heterojunction substantially promote electron-hole (e − -h + ) pairs separation and transfer. Profited from their synergistic effects, the 2D/3D BiOI/g-C 3 N 4 heterojunction delivers superior photocatalytic activity toward four different types of pollutants: methylene blue (91.7 %), tetracycline (91.9 %), eosin y (90.9 %) and methyl orange (97.7 %), and demonstrates excellent cyclic stability after seven methylene blue cyclic degradation experiments. Furthermore, BiOI/g-C 3 N 4 has shown satisfactory practicability in many simulation experiments, such as coexisting cations, different pH and real water. A feasible strategy to prepare a visible-light-driven multidimensional coordinated S-scheme heterojunction photocatalyst is provided in this work.