Fabrication of ternary g-C3N4/Al2O3/ZnO heterojunctions based on cascade electron transfer toward molecular oxygen activation

The mismatches of lattices and energy bands in heterojunction are the dominant factors restricting the generation efficiency of reactive oxygen species (ROS) that are powerful tools for water purification and anti-bacteria. In this paper, the mediated lattice matching role of amorphous Al 2 O 3 is presented for constructing the ternary g-C 3 N 4 /Al 2 O 3 /ZnO heterojunctions, which exhibit higher molecular oxygen activation performance than binary g-C 3 N 4 /ZnO and g-C 3 N 4 /Al 2 O 3 heterojunctions. The oxygen activation ability and the ROS generation were testified by the electron paramagnetic resonance (EPR) measurement, transformation of nitroblue tetrazolium (NBT) and degradation of methylene blue (MB). The ROS include superoxide anion radical ( O 2 − ) and consequent product of hydroxyl radical ( OH). The superior oxygen activation performance of the ternary heterojunctions can be attributed to the lattices matching of the mediated amorphous Al 2 O 3 and the resultant efficient cascade electron transfer.