Modulation of internal electric field in S-scheme heterojunction towards efficient photocatalytic CO2 conversion

The internal electric field (IEF) inherent within a composite photocatalyst plays a pivotal role in orchestrating the photogenerated charge carrier separation. Consequently, achieving precise regulation of the IEF emerges as the keystone for optimizing photocatalytic performance. Herein, we present a demonstrative study centered around the deliberate manipulation of the IEF within a g-C3N4/In2S3 step-scheme (S-scheme) heterojunction. This manipulation is deftly accomplished through the introduction of sulfur doping (S-doping) into the g-C3N4. Employing advanced techniques such as Kelvin probe force microscopy and density functional theory calculations, we substantiate that S-doping precipitates a reinforcement in IEF existing between g-C3N4 and In2S3. The soundness of this proposition is fortified through in situ X-ray photoelectron spectroscopy, which unveils a pronounced augmentation in the accumulation of photogenerated electrons on the surface of g-C3N4 subsequent to S-doping. This empirically substantiates the enhanced charge carrier dynamics made possible by the manipulation of the IEF within S-scheme heterojunction.