Investigating S-scheme charge transfer pathways in NiS@Ta2O5 hybrid nanofibers for photocatalytic CO2 conversion

Abstract

Investigating the charge-transfer behavior of photocatalysts is important to promote the photoreduction of CO2 into solar fuels. Therefore, in this study, hybrid Ta2O5 nanofibers were produced through the in situ growth of freestanding NiS nanosheets. The charge separation and CO2 photoreduction mechanisms of these nanofibers were investigated using in situ X-ray photoelectron spectroscopy and density functional theory calculations. The results suggested that the NiS@Ta2O5 nanohybrids formed an S-scheme heterojunction, which promoted the efficient separation of electron-hole pairs and enhanced CO2 photoreduction. Compared to the pristine Ta2O5 nanofibers, the hybrid nanofibers exhibited a significantly higher CO2-reduction rate (43.27 μmol g−1 h−1 for CO; 6.56 μmol g−1 h−1 for CH4). In situ diffuse reflectance infrared Fourier-transform spectroscopy results confirmed the process of CO2 hydrogenation and S-scheme charge transfer pathways in NiS@ Ta2O5 nanohybrids.