Tip-induced directional charge separation on one-dimensional BiVO4 nanocones for asymmetric light absorption

Abstract

One dimensional (1D) semiconductor is a class of extensively attractive materials for many emerging solar energy conversion technologies. However, it is still of shortage to assess the impact of 1D structural symmetry on spatial charge separation and understand its underlying mechanism. Here we take controllably-synthesized 1D BiVO4 nanocones and nanorods as prototypes to study the influence of 1D symmetry on charge separation. It is found that the asymmetric BiVO4 nanocones enable more effective charge separation compared with the symmetric nanorods. The unexpected spatial charge separation on the nanocones is mainly ascribed to uneven light absorption induced diffusion-controllable charge separation due to symmetry breaking of 1D nanostructure, as evidenced by spatial and temporal resolved spectroscopy. Moreover, the promotion effect of charge separation on the nanocones was quantitatively evaluated to be over 20 times higher than that in BiVO4 nanorods. This work gives the first demonstration of the influence of 1D structural symmetry on the charge separation behavior, providing new insights to design and fabricate semiconductor materials for efficient solar energy conversion.