Unveiling Carrier Dynamics in Periodic Porous BiVO4 Photocatalyst for Enhanced Solar Water Splitting

Improved photocatalytic activities in highly ordered porous photocatalysts are often attributed to the larger surface area, higher light absorption, and suppressed charge recombination. Other underlying reasons for the improved charge transport, however, remain elusive at this stage. Herein, 3DOM BiVO4 photocatalysts are examined to understand the carrier dynamics and their effects in photocatalytic water splitting. Quantum confinement arising from the ultrathin and crystalline wall upshifted its conduction band, enabling photocatalytic proton reduction to hydrogen gas under visible-light illumination. Time-resolved microwave conductivity spectroscopy reveals its similar to 6 times higher charge mobility and longer charge diffusion length relative to the bulk counterpart. The long lifetime (similar to 360 ns) of 3DOM BiVO4 with a power-law decay suggests the improved charge separation and the formation of shallow trapping states. Further investigation by Kelvin probe force microscope discloses a built-in electric field with upward band bending from the internal wall to the interconnection part of 3DOM BiVO4.

Automated summary

The study found that the 3DOM BiVO4 photocatalysts can enhance the mobility and diffusion length of charge carriers, enabling the photocatalytic proton reduction reaction and forming shallow trapping states, thereby prolonging the charge lifetime.