2024/10/25 by Fengke Sun, Yuting Deng, Jing Leng +5 · 5 citations
Materials Science · #Electronic and Structural Properties of Oxides #Ga2O3 and related materials #Luminescence Properties of Advanced Materials
paper · pdf · doi:10.1021/jacs.4c10962
High Resolution Image Download MS PowerPoint Slide Photogenerated charge separation is pivotal for effecting efficient photocatalytic reactions. Understanding this process with spatiotemporal resolution is vital for devising highly efficient photocatalysts. Here, we employed pump–probe transient reflection microscopy to directly observe the temporal and spatial evolution of photogenerated electrons and holes on the surface of facet-engineered bismuth vanadate (BiVO 4 ) crystals. The findings suggest that the anisotropic built-in field of BiVO 4 crystals propels the separation of photogenerated electrons and holes toward different facets through a two-step process across varying time scales. Photogenerated electrons and holes undergo ultrafast separation within ∼6 ps, with electrons transforming into localized small polarons toward the 010 facets of truncated BiVO 4 octahedral crystals. However, the photogenerated holes prolong their separation up to ∼2000 ps in a drift–diffusion manner before ultimately accumulating on the 120 facets. This work provides a comprehensive visualization of spatiotemporal charge separation at the nano/microscale on semiconductor photocatalysts, which is beneficial for understanding the photocatalysis mechanism.