Highly Oriented Nitrogen-Doped Flower-like ZnO Nanostructures for Boosting Photocatalytic and Photoelectrochemical Performance: A Combined Experimental and DFT Study

A facile method to modify the ZnO catalyst by nitrogen doping and synthesis of a highly oriented flower-like structure is reported. The generated system exhibits an enhanced photoinduced charge separation through the lightning rod effect. A well-aligned structure and high aspect ratio of ZnO nanorods is confirmed by the XRD, FESEM and TEM analyses. Efficient photogenerated charge transfer is achieved upon light irradiation, as confirmed by PL and EIS studies. Density functional theory (DFT) calculations provide an atomistic understanding of the modified electronic structure of N-doped ZnO. N-doped ZnO with 5 wt % exhibits the best photocatalytic performance. When applied to the photoelectrochemical water splitting, the optimal catalyst can achieve a remarkable photocurrent density of 4.0 mAcm^-2 at the lowest onset potential of 0.61 V vs Ag/AgCl (1.40 V vs RHE). The reported work demonstrates that rational design of doped materials opens up new avenues for catalyst development.