Chengyi Dai,Xiao Zhao,Borui Hu,Xinbao Zhang,Qunxing Luo,Xinwen Guo,Xiaoxun Ma
Capturing and utilization of carbon dioxide (CO 2 ) not only leads to effective use of carbon resources, but also alleviates environmental pollution caused by increasing concentration of CO 2 , thus making it a hot research topic in recent years. In this study, a series of highly dispersed iron-cobalt (Fe-Co) catalysts was prepared by ethylenediaminetetraacetic acid disodium salt (EDTA-2Na) modification, which could efficiently convert CO 2 into high value-added chemicals (C 2 -C 4 = and C 5 -C 11 ). X-ray diffraction (XRD) analysis showed that the addition of a small amount of Co and EDTA-2Na contributed to enhance the sintering resistance of Fe species. During the calcination process, EDTA 4− can be decomposed into small organic molecules with reducibility, thus promoting the reduction of iron species. The CO temperature-programmed desorption (CO-TPD) results showed that cobalt enhanced the adsorption and activation of intermediate CO on Na x Fe-Co catalyst, thereby promoting the catalytic conversion of CO 2 . The complexation of EDTA promotes the synergistic effect of Fe-Co bimetals, enhances the chemical adsorption of CO 2 . Sodium in EDTA-2Na promotes the surface basicity of the catalysts, which is favored for improving the product distribution of hydrocarbons. At lower H 2 /CO 2 (1/1) ratio, the EDTA-2Na modified Fe-Co/Al 2 O 3 catalyst exhibited high conversion of CO 2 (32.8 %) and excellent selectivity toward high value-added chemicals. The selectivity of by-product CO was only 8.1 %; and C 2 -C 4 = (32.5 %) and C 5 -C 11 (46.3 %) accounted for ∼79 % selectivity among the hydrocarbons generated.
The development of an efficient, stable and low-cost cathode catalyst is necessary for the practical application of Zn-air batteries. In this paper, Fe3+/Co2+ ions were in situ incorporated into polydopamine during the polymerization of dopamine on the surface of the SiO2 spheres. After subsequent pyrolysis and leaching SiO2, the products loaded with different metals (NHCS-Fe, NHCS-Co, NHCS-Fe1Co0.6, NHCS-Fe1Co4, NHCS-Fe1Co10) were obtained. The samples possess a typical hollow carbon sphere (HCS) structure and show efficient oxygen reduction reaction (ORR) performance under neutral and alkaline conditions. Especially in the neutral electrolyte, the NHCS-Fe exhibits the comparable electrochemical catalytic activity to the commercial Pt/C. For NHCS-Fe, its ORR half-wave potential in neutral and alkaline media is 0.78 V and 0.83 V respectively. Corresponding neutral Zn-air battery reveals a maximum power density of 118.8 mW·cm−2, while they are respective 0.82 V and 46.99 mW·cm−2 for Pt/C. Alkaline Zn-air battery with NHCS-Fe releases a maximum power density of 262.4 mW·cm−2, displaying superior performance to Pt/C. Our work is instructive for the synthesis of novel ORR catalysts with outstanding activity by a versatile synthesis strategy.
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