Revealing charge migration in a Multi-Multi photocatalyst by in situ irradiated X-ray photoelectron spectroscopy

Constructing efficient photocatalysts to produce solar fuels has been regarded as a potential way to alleviate energy crisis and environmental pollution. So far, simply modified single- and dual- component photocatalysts still suffer low efficiency due to their inherent weaknesses, making researchers turn their attention to multiple modified multi-component photocatalysts (“multi-multi” photocatalysts). However, the complex structure and composition of “multi-multi” photocatalysts will make it difficult for in-depth investigations on their working mechanisms, principally due to the lack of a method for direct observation of the migration route of charge carriers under the light irradiation in these systems. Herein, we report an in situ irradiated X-ray photoelectron spectroscopy (ISI-XPS) method to show the transfer pathway of charge carriers through the shifts of binding energies using a triple-modified WS2/carbon nanofibers (CNFs)/ZnIn2S4 model system. With this method, we manage to reveal the role of each subcomponent and demonstrated that the synergy of multiple modifications significantly enhances the performance of the “multi-multi” photocatalyst. This novel method opens up a new avenue for studying the mechanisms of photocatalytic systems, facilitating the future development of highly efficient photocatalysts.