Nonstoichiometric perovskite CaMnO3-δ nanomaterial for photocatalytic reduction of CO2

Nanostructured perovskite oxides have emerged as a class of high-performance photocatalytic materials. In this study, the nonstoichiometric perovskite CaMnO3-delta nanomaterial is reported as a potential photocatalyst under IR and visible irradiation. The as-prepared sample was characterized by Brunauer-Emmett-Teller (BET) method and the diffuse reflectance spectroscopy (DRS). The CO2 photoreduction and methanol yield over CaMnO3-delta under both infrared and visible light irradiation as a function of irradiation time and photocatalyst concentration were investigated by chemical titration and the gas chromatographic analysis (GC-FID). The first and second harmonics of Nd:YAG laser with wavelengths of 1064 and 532 nm were used as the excitation source. After 20 min of 532 nm irradiation, the methanol yield for catalyst concentration of 0.6 g/lit exhibited the highest value (1138 mu mol/g), while the methanol started to degrade with the increase of irradiation time. We have shown that under visible and IR irradiations, the electron photoexcitation from the hybridized O-2p and Mn-3d e(g)up arrow 1 valance band to the Mn-3d e(g)up arrow 2 conduction band provided CO2 center dot delta- anion radicals which are required for CO2 photoreduction to methanol. This study makes the nonstoichiometric CaMnO3-delta a promising active catalytic material for CO2 photoreduction to methanol under IR and visible light irradiation.

Automated summary

Nanostructured perovskite oxides, particularly the nonstoichiometric perovskite CaMnO3-delta nanomaterial, have shown promising potential as high-performance photocatalysts under IR and visible light irradiation for CO2 photoreduction to methanol. The study demonstrated that electron photoexcitation from O-2p and Mn-3d e(g)up arrow 1 valance band to Mn-3d e(g)up arrow 2 conduction band provides the necessary radicals for CO2 reduction. This research highlights the potential of CaMnO3-delta as an active catalytic material for CO2 photoreduction to methanol under both visible and IR irradiation.