Dou Zhang,Bo-hui Li,Yi-lei Li,Jun Zhao,Xiao-jing Wang,Fa-tang Li
The efficient conversion of CO 2 to carbon-neural fuels by photocatalysts can effectively address the increasingly prominent challenges of environmental pollution and energy shortage. TiO 2 is considered a promising photocatalyst. However, its disadvantages, such as poor adsorption of CO 2 and low carrier separation efficiency, inhibit its performance and selectivity in photocatalytic CO 2 reduction. Herein, K + -modified anatase TiO 2 ultrathin nanosheet photocatalysts were obtained via a reverse etching method using K 2 Ti 8 O 17 as the precursor. The selectivity of the optimized photocatalyst for methane was 96.02% in a gas–solid system without additives, with an excellent photocatalytic rate of 42.3 μmol·g −1 ·h −1 , which was 3.39 times higher than that of P25. The effects of K + on photocatalytic behaviors and the selectivity of CH 4 was systematically investigated. The test results showed that during treatment with formic acid, a large amount of K + from the layered K 2 Ti 8 O 17 were removed and the original structure was destroyed. Therefore, highly dispersed TiO 2 nanosheets were obtained, with a small amount of K + remaining on the TiO 2 surface. The well-defined rectangular shapes of TiO 2 reduce the transmission distance of photogenerated carriers, whereas the presence of K + increase the chemisorption of CO 2 molecules, thereby activating CO 2 , promoting the conversion of bridge *CO to -CHO, and increasing CH 4 production. This study provides insightful references for the preparation and modification of traditional photocatalysts for photocatalytic CO 2 reduction reactions.
Yi Jing Jia,Jin Quan Tao,Hao Ran Liu,Wen Bin Huang,Rongpeng Yao,Miaomiao Niu,Rongrong Li,Qiang Wei,Ya Song Zhou
To enhance the CO 2 hydrogenation activity and low-carbon olefin selectivity of Fe-based catalysts, a strategy involving the use of metal promoters to modulate the structure of active metal centers in catalyst preparation was proposed. The incipient wetness impregnation method was used to introduce modifying agents K and/or Co into the Fe/Al 2 O 3 catalyst. Characterization techniques such as XRD, BET, SEM, HRTEM, H 2 -TPR, XPS, CO 2 -TPD, NH 3 -TPD, and TG were employed to investigate the effects of the modifying agents on the dispersion, reducibility, electronic properties, and acid–base properties of active metal species. Furthermore, the influence of K and Co modification on the CO 2 hydrogenation activity and low-carbon olefin selectivity of Fe/Al 2 O 3 catalysts was explored. The results revealed that the introduction of K generated more basic sites and electron-rich active metal centers in the catalyst, facilitating the adsorption and activation of CO 2 , while suppressing the hydrogenation of olefins and the formation of methane, thus improving the selectivity towards low-carbon olefins. Co promoter facilitated the dispersion of Fe species, exposing more active sites and enhancing the FTS reaction activity, leading to more CO being converted into C 2+ hydrocarbon products. Under the synergistic effect of K and Co, the CO 2 conversion activity of the Fe-based catalyst significantly increased, achieving a CO 2 conversion rate of 37%, while the selectivity towards C 2 -C 4= increased to 31.9%.
危险品化学品经营许可证（带存储）