Photoassisted Batch Injection Analysis (photoBIA): Monitoring Photoelectrochemical Activity of Catalysts.

We introduce photoassisted batch injection analysis (photoBIA), a novel analytical system that integrates photoelectrochemistry with batch injection analysis (BIA), as a sensitive, reproducible, and time-resolved method for evaluating the activity of light-sensitive semiconductor electrodes. Using BiVO4 and α-Fe2O3/TiO2 as model semiconductor photoanodes and alcohols (methanol and glycerol) as probe molecules, the photoBIA enables precise delivery of analytes onto an illuminated photoelectrode through hydrodynamic injection, generating sharp faradaic current transients, characteristic of photoelectrooxidation events. The system was benchmarked against conventional stationary photoelectrochemical cells, which exhibited a limited mass transport and low temporal resolution. In contrast, photoBIA allowed for rapid detection of interfacial processes with clear discrimination under light and dark conditions. These results demonstrate the potential of photoBIA for rapid screening of photosensitive catalysts under well-controlled and realistic conditions, providing information for evaluating potential photoanodes or photocathodes in fuel cell development and light-driven electrochemical systems.