Polar-surface-dominated zigzag GaN nanowires with alternate H2 and O2 evolution sites for photocatalytic overall water splitting

Abstract

Photocatalytic overall water splitting is an ideal green technology to produce the clean and renewable hydrogen energy. Herein, high crystalline zigzag GaN nanowires (NWs) are successfully synthesized through an Au-catalyzed chemical vapor deposition process. The single-crystalline zigzag nanowire is a polar-surface-dominated nanostructure composed of Ga and N atoms alternately as a result of the inherent surface atomic termination and polar charges. Compared with the non-polar-dominated smooth-surfaced nanowires, the zigzag nanowires attain multifold H2 and O2 evolutions in the presence of respective sacrificial reagents. More importantly, the zigzag nanowires realize the stoichiometric overall pure water splitting, due to the synergistic effect of the internal electric field between Ga-terminated and N-terminated facets that drives the spatial charge separation, the high charge mobility and polar surface energy. This work suggests that constructing polar surface on one-dimensional nanomaterial with spatially separated H2 and O2 evolution sites could be employed as a new crystal engineering strategy for designing efficient photocatalysts towards overall water splitting.