Unveiling the Size-Dependent Photothermal Synergy of TiO<sub>2</sub> in Catalytic CO<sub>2</sub> Reduction
Haodong Zhang, Min Chen, Weiming Qian, Jianghao Zhang, Xueyan Chen, Xiaoxiao Qin, Minmin Liang, Changbin Zhang
Abstract
The hydrogenation of CO 2 to produce valuable chemicals through photocatalytic or photothermal technologies represents a viable path toward carbon neutrality. However, typical nanosemiconductor materials, such as TiO 2, often exhibit limited activity, necessitating the optimization of their performance as a key research priority. Here, we demonstrate that the size of anatase TiO 2 significantly influences its performance in the selective photocatalytic and photothermal reduction of CO 2 to CO. The small-sized TiO 2 (S-TiO 2, 15 nm) exhibits a low CO yield of 32.7 μmol g –1 h –1 and shows almost no photothermal synergy. In contrast, the large-sized TiO 2 (L-TiO 2, 160 nm) demonstrates a high CO yield of 185.3 μmol g –1 h –1 and significant photothermal synergy, with the CO yield reaching 438.7 μmol g –1 h –1 . We reveal that L-TiO 2 is well-crystallized and has a higher conduction band position compared to the S-TiO 2 . This results in a higher charge separation efficiency and more effective photoexcited electrons for CO 2 reduction. Additionally, the external heating primarily enhances the charge separation in L-TiO 2, significantly improving the conversion of CO 2 to CO. This work provides insights into the relationship between the structure and activity of TiO 2 in photocatalytic and photothermal CO 2 reduction.