Defect Engineering of Two-Dimensional Nb-based Oxynitrides for Visible-Light-driven Water Splitting to Produce H2 and O2

Substituting Nb with Ta decreased the defect density of oxynitrides and also provided a tunable bandgap from 1.77 to 2.12 eV, thus delivering maximum H 2 and O 2 evolution rates of 19.37 and 22.81 μmol h −1 , respectively.