Mengrong Zhang,Sha Ni,Zichao Yang,Min Zhang,Zhongjie Guan,Jianjun Yang
Graphical Cu-modified monoclinic TiO 2 nanoflowers with OVs (Cu 1 TB-1.5) promote the reactivity and selectivity of CO 2 reduction to CO under visible light. CO selectivity is 99.6%, and the cycling stability is excellent. The Cu 1 TB-1.5 facilitates the formation of the intermediate COOH* during the photocatalytic process, thus improving the yield and selectivity of CO. The photoreduction of CO 2 has attracted extensive attention as a promising solution to global warming. In this study, Cu-modified TiO 2 (B) (CuTB) nanoflowers with oxygen vacancies (OVs) are designed and synthesized via hydrothermal treatment and photodeposition to promote the reactivity and selectivity of CO 2 reduction to CO under visible light. The CO and CH 4 yields of sample Cu 1 TB-1.5 under visible light are 5.72 and 0.02 μmol g −1 h −1 , wherein the CO yield was 15.5 times that of sample TB; its selectivity is 99.6%, and the cycling stability is excellent. OVs can broaden the light absorption of TB to the visible light region, and Cu promotes photoinduced electron transfer from TB to the Cu species and act as an active center. The OVs and Cu can synergistically enhance charge separation, CO 2 adsorption, and CO 2 conversion. The Cu 1 TB-1.5 facilitates the formation of the intermediate COOH* during the photocatalytic process, thus improving the yield and selectivity of CO. This research provides a unique idea for the development of novel highly selective photocatalysts.
Ye Liu,Lei Zhang,Yubo Kuang,Xiaoqian Xiang,Haohan Tao,Guangran Di,Xiaojing Yin,Meicheng Li,Xiao-Jun Lv
The photocatalytic CO 2 reduction has the problems of low selectivity of single product. Here, the preparation of Cu modified tubular C 3 N 4 (CTN) was studied. The increase of the active site inhibits the recombination of electrons (e-) and holes (h + ) and improves the selectivity of CO 2 reduction products. Finally, the CO and CH 4 yields of 1.5 % CTN photocatalyst are 11.55 μmol·g −1 and 4.72 μmol·g −1 , respectively, which are 5 times higher than that of tubular C 3 N 4 photocatalyst. The selectivity of 2 % CTN to CH 4 is up to 68 %, indicating that the prepared CTN photocatalyst has high CO 2 reduction activity and CH 4 selectivity.
A one-pot synthetic method was used to prepare copper (Cu)-modified manganese (Mn)-rich MnSAPO-34 catalysts, which were then used for NO x removal from stationary-source flue gas. The addition of Cu to these Mn-rich MnSAPO-34 catalysts significantly enhanced their low temperature (LT) selective catalytic reduction (SCR) activity and H 2 O resistance. The Mn 0.4 Cu 0.05 SAPO-34 catalysts demonstrated excellent LT NH 3 -SCR activity, with NO x removal being >90% from 160 to 300 °C. In addition, Mn 0.4 Cu 0.05 SAPO-34 catalysts exhibited high H 2 O resistance. This excellent performance was ascribed to strong synergistic effects between Mn 4+ and isolated Cu 2+ species in Mn 0.4 Cu 0.05 SAPO-34 catalysts, leading to suitable redox ability. The results of in situ FT-IR analysis indicated that LT-SCR reactions mainly proceeded by an Eley–Rideal reaction pathway at 200 °C in Cu-modified manganese-rich MnSAPO-34 catalysts. Thus, Mn 0.4 Cu 0.05 SAPO-34 was considered as a promising candidate for NO x removal from flue gas of stationary sources at low temperatures.
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