Fig. 1

Theoretical calculations. a Optimized geometrical structure of PB and ZnPB with various doping levels (colour coding: Fe(III)-red, Fe(II)-yellow, Zn-blue, N-grayish and C-dark grey); 3D charge density difference plot of the optimization of PB and ZnPB. b 2D heatmap of differential charge density of PB and ZnPB in the midpoint of each unit cell