Effect of CoOx and Rh Cocatalysts on Local Charge Carrier Dynamics of BiVO4 Particles by Pattern-Illumination Time-Resolved Phase Microscopy

Photocatalysis of bismuth vanadate (BiVO4) particles can be enhanced by selectively loading cocatalysts on different facets. Using BiVO4 loaded with CoOx on oxidation facets and Rh on the reduction facets as a model, we studied the effects of selectively loaded cocatalyst on the local charge carrier dynamics by pattern-illumination time-resolved phase microscopy. The local charge carrier dynamics were analyzed by clustering analyses of the charge carrier responses, and they were categorized in the presence and absence of the cocatalysts. From the mapping of the charge carrier types with and without scavengers, the electron and hole responses trapped to cocatalysts were assigned successfully, and they were spatially separated at the local positions of the particles and/or aggregates. It was clarified that CoOx and Rh could keep the holes and electrons on the order of several microseconds and hundreds of nanoseconds, respectively.