Step-by-Step Mechanism Insights into the TiO₂/Ce₂S₃ S‑Scheme Photocatalyst for Enhanced Aniline Production with Water as a Proton Source

Exploring heterostructured photocatalysts for the photocatalytic hydrogenation reaction with water as a proton source and investigating the corresponding intrinsic step-by-step mechanism are of great interest. Here, we develop an S-scheme heterojunction through theoretical design and carried out solvothermal growth of Ce₂S₃ nanoparticles (NPs) onto electrospun TiO₂ nanofibers. The low-dimensional (0D/1D) heterostructure unveils enhanced photocatalytic activity for aniline production by nitrobenzene hydrogenation with water as a proton source. Density functional theory (DFT) calculations indicate the electrons transfer from Ce₂S₃ to TiO₂ upon hybridization due to their Fermi level difference and creates an internal electric field at the interface, driving the separation of the photoexcited charge carriers, which is authenticated by in situ X-ray photoelectron spectroscopy along with femtosecond transient absorption spectroscopy. The step-by-step reaction mechanism of the photocatalytic nitrobenzene hydrogenation to yield aniline is revealed by in situ diffuse reflectance infrared Fourier transform spectroscopy, associated with DFT computational prediction.