Decoupled Crystallization and Particle Growth of BiVO4 via Rapid Thermal Process for Enhanced Charge Separation

Abstract BiVO 4 is one of the most promising candidates for photoelectrochemical water oxidation. However, the poor crystallinity and short hole diffusion length limit its charge separation. One bottleneck stems from the contradiction between high crystallinity and small particles via conventional furnace heating processes. This paper describes the design and fabrication of BiVO 4 photoanodes via rapid thermal process (RTP), rather than furnace heating, to decouple the constraints between nucleation, crystallization, and growth processes of BiVO 4 . The higher heating ramp rate of RTP compared with furnace heating promotes the fast diffusion of reactant molecules, which elevates the nucleation rate above the particle growth rate of BiVO 4 , leading to small particles with high crystallinity. Moreover, the ultra‐high heating temperature makes it possible to crystallize the small BiVO 4 particle within a short time. Thus, a high crystallinity can be obtained for the RTP‐treated BiVO 4 while maintaining small particle size, achieving a charge separation efficiency of up to 82%, 30% higher than that of furnace‐treated BiVO 4 photoanode.