Crystallinity control on Bi2MoO6 microspheres for improved photocatalytic oxygen evolution

Abstract

Crystallinity of the photocatalyst has a profound impact on its reactivity. Here, flower-like Bi2MoO6 microspheres were synthesized via a solvothermal method and subsequently calcined at varying temperatures to regulate the crystallinity and particle size. The thermally treated samples exhibited enhanced photocatalytic oxygen evolution compared to the pristine Bi2MoO6. Higher calcination temperatures led to the formation of larger crystallites, significantly boosting the activity. We demonstrate that crystallinity, rather than surface area, plays a more vital role in governing the photocatalytic performance of Bi2MoO6. Improved crystallinity can thicken the space charge layer (SCL), resulting in a greater band bending that facilitates the separation of electron-hole pairs. Conversely, poor crystallinity leads to an abundance of surface and bulk defects, promoting electron-hole recombination. Overall, efficient charge separation and suppressed recombination endow the calcined Bi2MoO6 with enhanced water oxidation efficiency.