2D-2D g-C3N4/K+Ca2Nb3O10− nanosheet heterojunctions were fabricated.
The g-C3N4/K+Ca2Nb3O10− heterojunctions have strong interfacial interaction.
The nanosheet heterojunctions showed enhanced visible light photocatalytic activity.
The enhanced activity was mainly due to the synergistic effect of heterojunctions.
The superoxide radicals and holes are the two main photoactive species.