Jie Deng,Wanying Lei,Junwei Fu,Huile Jin,Quanlong Xu,Shun Wang
Herein, photocatalytic selective oxidation of hydrocarbons through O 2 represents a promising way for fine chemical industry on account of its mild reaction condition. In this work, Co 3 O 4 -modified BiOBr/AgBr S-scheme heterojunction can effectively oxidize sp 3 C H bonds at benzylic position to its corresponding aldehydes, with a toluene to benzaldehyde selectivity of 94%, which is much higher than that of pure BiOBr (21.7%) and AgBr (58.9%). A unique S-scheme charge-transfer mode is confirmed for the ternary composites by the X-ray photoelectron spectroscopy and reactive species quenching measurement. The remaining photogenerated electrons in AgBr with powerful reduction ability can react with O 2 to generate •O 2 − species, which can further oxidize the benzyl radical formed on the Co 3 O 4 surface to peroxyl radicals and then thermodynamically decompose to benzaldehyde. Herein, this work has important guiding significance for the structure regulation of photocatalysts and application in selective oxidation of sp 3 C H bond of hydrocarbons.
Guanyu Chen,Weixin Zhang,Rongshu Zhu,Yanpeng Chen,Minghu Zhao,Mei Hong
Zeolite-based catalysts efficiently catalyze the selective catalytic reduction of NOxwith methane (CH4-SCR) for the environmentally friendly removal of nitrogen oxides, but suffer severe deactivation in high-temperature SO2- and H2O-containing flue gas. In this work, SSZ-39 zeolite (AEI topology) with high hydrothermal stability is reported for preparing CH4-SCR catalysts. Mild acid leaching with oxalic acid (OA) not only modulates the Si/Al ratio of commercial SSZ-39 to a suitable value, but also removes some extra-framework Al atoms, introducing a small number of mesopores into the zeolite that alleviate diffusion limitation. Additional Co3O4modification during indium exchange further enhances the catalytic activity of the resulting In-Co3O4/H-SSZ-39(OA). The optimized sample exhibits remarkable performance in CH4-SCR under a gas hourly space velocity (GHSV) of 24,000 h−1and in the presence of 5 vol% H2O. Even under harsh SO2- and H2O-containing high-temperature conditions, it shows satisfactory stability. Catalysts containing Co3O4components demonstrate much higher CH4conversion. The strong mutual interaction between Co3O4and Brønsted acid sites, confirmed by the temperature-programmed desorption of NO (NO-TPD), enables more stable NxOyspecies to be retained in In-Co3O4/H-SSZ-39(OA) to supply further reactions at high temperatures.
Yu Zidong,Liu Xiaojuan,Liu Zhicheng,Liu Ye,Su Chao,Sun Zhi,Du Jilei,Wei Tao
Sodium-ion batteries (SIBs) have recently gained wildly interest due to the abundance of sodium, lower production costs, and better low-temperature performance compared to lithium-ion batteries (LIBs). Among various cathode materials of SIBs, O3-type NaNi 0.4 Fe 0.2 Mn 0.4 O 2 (NFM424) demonstrates high capacity and ease of synthesis, yet suffers from structural degradation and sluggish Na + kinetics caused by large ionic radius and strong electrostatic interactions. To overcome these issues, a configuration strategy combined with TiO 2 and Co 3 O 4 by a simple solid-state reaction method was introduced to improve structural and electrochemical stability. XRD, SEM, TEM, and various electrochemical characterizations as well as TGA/DSC tests were conducted. The resulting NaNi 0.4 Fe 0.2 Mn 0.3 Co 0.05 Ti 0.05 O 2 (NFMCT) cathode mitigated Jahn-Teller distortions and Na + /vacancy ordering while enhancing phase integrity and diffusion pathways. The obtained NFMCT maintained 93.7 mAh·g −1 after 550 cycles at 1 C, with superior rate capabilities at 2 C and 5 C. These findings deepen the understanding of configuration strategy by using multi-element oxide and highlight a practical strategy for designing high-performance SIB cathodes.
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