Photocatalytic reduction of CO2 using H2 as reductant over ATaO3 photocatalysts (A = Li, Na, K)

Abstract

ATaO 3 (A = Li, Na, K) compound oxides exhibit photocatalytic activity for the reduction of CO 2 in the presence of H 2. Only CO gas was generated over all samples under photoirradiation. The photocatalytic activity was higher in the order corresponding to KTaO 3 , NaTaO 3 and LiTaO 3 (LiTaO 3 > NaTaO 3 > KTaO 3). The order of the photocatalytic activities was consistent with that of the E g (optical gap) values. After 24 h of photoirradiation, the amount of evolved CO reached 0.42 µmol•g-1 over LiTaO 3. TPD experiments indicated that the broad peak which is assigned to chemisorbed CO 2 gas was observed at 573 K in the case of LiTaO 3. On the contrary, there was no peak in the spectra of NaTaO 3 and KTaO 3. The amount of evolved CO gas almost strongly depends on amount of chemisorbed CO 2 in the case of ATaO 3 (A = Li, Na, K). In addition, the photocatalytic activity increased with increasing the calcination temperature of LiTaO 3. This means that a smooth charge separation in a LiTaO 3 photocatalyst and chemisorption of CO 2 on the surface contribute to effective reduction of CO 2 in the presence of H 2. Teramura et al. Photocatalytic reduction of CO 2 over ATaO 3 4 / 21

A perspective on perovskite oxide semiconductor catalysts for gas phase photoreduction of carbon dioxide

“…CO was the only gaseous product over all of the samples tested under 200 W Hg-Xe lamp irradiation. [54] LiTaO 3 presented the highest activity for CO yield (0.42 µmol/g in 24 h), and the trend of the photocatalytic activities were consistent with that of the E g (LiTaO 3 > NaTaO 3 > KTaO 3 ). In addition, they also found that the amount of evolved CO gas depended on the amount of chemisorbed CO 2 (as shown in Fig.…”

“…In addition, they also found that the amount of evolved CO gas depended on the amount of chemisorbed CO 2 (as shown in Fig. 2), [54] which meant that the adsorption of CO 2 had an effect on the reduction efficiency of CO 2 . H 2 was used as reductant in this photocatalytic reduction of CO 2 process, whereas other gas reaction systems usually used H 2 O as reductant.…”

“…This yield is relatively low compared with the conversion of water splitting. [14][15][16][45][46][47][48][49][50][51][52][53][54] The conversion efficiency and [ 45] ). [14] ).…”

“…Wang et al first reported the photocatalytic properties of BaCeO 3 , whose conduction band mainly consists of Ce 4f orbitals, as a new photocatalyst for gas phase CO 2 reduction. [15] The activity of [ 54] ). (Copyright 2012, The Journal of Physical Chemistry.…”

Light-Promoted Hydrogenation of Carbon Dioxide—An Overview

“…The order of CO2 reduction activity on alkaline perovskites (LiTiO3 > NaTiO3 > KTiO3) was also found to correlate to some extent with the measured chemisorption capacity [36]. A screening on several oxides performed by the same research team revealed that, in addition to other basic oxides such as CaO, the activity was surprisingly high using Ga2O3 [37][38].…”