A TiO2/hydrazine system was investigated as a proof-of-concept platform for coupling chemical CO2 capture with light-driven H2 evolution under UV irradiation. Hydrazine served as the CO2 capture agent, leading to the formation of carbamate-type intermediates, while TiO2 acted as the photoresponsive solid. FT-IR, UV-Vis, and mass spectrometry analyses supported carbamate formation after CO2 uptake and confirmed H2 generation during irradiation, reaching a maximum of 33.2 μmol under the conditions evaluated. Deuterated experiments showed no detectable HD or D2, indicating that H2 evolution predominantly proceeded via hydrazine dehydrogenation rather than direct water splitting. On the basis of the available spectroscopic evidence, a tentative pathway involving carbamate intermediates and nitrogen-containing oxidation products is proposed. However, key control experiments required to confirm a strictly photocatalytic origin of H2 evolution were not performed in the present exploratory study. Therefore, the observed behavior is more appropriately interpreted as preliminary photoinduced reactivity in a TiO2/hydrazine/CO2 system rather than definitive proof of a fully established photocatalytic mechanism. Overall, the results establish a preliminary proof of concept, while the limitations related to control experiments, product identification, quantification, and reproducibility are recognized.
Valle et al. (Sat,) studied this question.