Cu/CeO2 catalysts for reverse water gas shift reactions: the effect of the preparation method.

The reverse water gas shift reaction is one of the most prospective CO2 utilization approaches. Cu has excellent selectivity for CO and CeO2 is rich in surface oxygen vacancies for CO2 activation. These unique properties are often used to develop efficient Cu/CeO2 catalysts in RWGS. In this paper, Cu/CeO2 is prepared by plasma-induced micro-combustion. The effect of the subsequent calcination after micro-combustion on the structure and catalytic property is systemically studied. Because of the mild temperature of micro-combustion, highly dispersed Cu species load on the surface of CeO2 for the catalyst without calcination (Cu/CeO2-mc). During calcination, the highly dispersed Cu species form two kinds of species, Cu-Ce solid solution structure and small CuO clusters (Cu/CeO2-mcc). The Cu-Ce solid solution effectively enhances the generation of oxygen vacancies, which improves the adsorption and activation of CO2. The catalytic performance of Cu/CeO2-mcc thereby is superior to Cu/CeO2-mc in RWGS. In situ diffuse reflectance infrared fourier transform spectroscopy analysis demonstrates that the formate pathway is the main mechanism of RWGS. CO2 adsorbed on the surface of Cu/CeO2-mcc mainly forms bidentate species. While monodentate generates on the surface of Cu/CeO2-mc. And decomposes to CO easier than , thus Cu/CeO2-mcc exhibits excellent catalytic properties. This work provides a new approach for structural modulation of catalysts with excellent catalytic performance in RWGS.

Recent Advances of Modified Ni (Co, Fe)-Based LDH 2D Materials for Water Splitting.

Water splitting technology is an efficient approach to produce hydrogen (H2) as an energy carrier, which can address the problems of environmental deterioration and energy shortage well, as well as establishment of a clean and sustainable hydrogen economy powered by renewable energy sources due to the green reaction of H2 with O2. The efficiency of H2 production by water splitting technology is intimately related with the reactions on the electrode. Nowadays, the efficient electrocatalysts in water splitting reactions are the precious metal-based materials, i.e., Pt/C, RuO2, and IrO2. Ni (Co, Fe)-based layered double hydroxides (LDH) two-dimensional (2D) materials are the typical non-precious metal-based materials in water splitting with their advantages including low cost, excellent electrocatalytic performance, and simple preparation methods. They exhibit great potential for the substitution of precious metal-based materials. This review summarizes the recent progress of Ni (Co, Fe)-based LDH 2D materials for water splitting, and mainly focuses on discussing and analyzing the different strategies for modifying LDH materials towards high electrocatalytic performance. We also discuss recent achievements, including their electronic structure, electrocatalytic performance, catalytic center, preparation process, and catalytic mechanism. Furthermore, the characterization progress in revealing the electronic structure and catalytic mechanism of LDH is highlighted in this review. Finally, we put forward some future perspectives relating to design and explore advanced LDH catalysts in water splitting.

Effect of template removal using plasma treatment on the structure and catalytic performance of MCM-22.

To investigate the effect of template removal methods on the structure, properties and catalytic performance of the MCM-22 zeolite, dielectric-barrier discharge (DBD) plasma treatment and thermal calcination have been comparatively studied for the removal of hexamethyleneimine (HMI) from the two-dimensional layered precursor of MCM-22 (MCM-22(P)). The materials were characterized using FT-IR, TG, XRD, N2 adsorption at low temperature, NH3-TPD, and 27Al and 29Si MAS NMR. The results revealed that the seven-membered heterocyclic compound HMI can be effectively removed from the MCM-22 zeolite, and the condensation of silanol groups on the neighboring surface of MWW nanosheets can be induced by DBD treatment. Compared with calcination, DBD treatment could preserve the structure well and decrease the formation of extra-framework aluminum. Consequently, the concentration of acidic sites over MCM-22 treated by DBD (MCM-22(DBD)) is higher than that over calcined MCM-22 (MCM-22(C)). Moreover, MCM-22(DBD) possesses a certain amount of external surface area derived from the intercrystal pores due to the inhibiting effect of the condensation of the silanol groups on the external surface of the MCM-22 crystals. The activity and product selectivity of the Fischer-Tropsch (FT) synthesis was investigated over cobalt supported on the obtained MCM-22 zeolites. Compared with Co/MCM-22(C), Co/MCM-22(DBD) shows a higher catalytic activity in the FT synthesis reaction. Moreover, Co/MCM-22(DBD) can effectively decrease CH4 selectivity and increase C5-C20 liquid fuel selectivity.

Characteristic and inheritance analysis of targeted mutagenesis mediated by genome editing in rice.

The transcription activator-like effector nucleases (TALEN) and clustered regularly interspaced short palindromic repeats/CRISPR-associated protein 9 (CRISPR/Cas9) systems are two current genome editing technologies. Here, we compare and analyze the characteristics of the targeted mutations mediated by these two systems, such as efficiency, type, position, time, and genetic patterns. Both the TALEN and CRISPR/Cas9 systems can induce site-specific mutations in T0 rice plants effectively, but CRISPR/Cas9 is more effective. The major mutation type in both systems is the short insertion/deletion(InDel) mutation within 10 base pairs: deletions ranging from 1 to 10 bps are more often in TALEN, and 1bp insertions are more often in CRISPR/Cas9. Moreover, double-strand breaks (DSBs) generated by CRISPR/Cas9 are more precise than TALEN. In addition, DSBs could be repaired by the homologous recombination at a low frequency, causing DNA fragment duplication mutations. In some cases, the DNA fragments between the two close targets are deleted or inverted, and the mutation efficiency does not positively correlatewith the mutation efficiency of each target. Mutagenesis mediated by the TALEN or CRISPR/Cas9 system can occur as early as in transformed callus cells, and less frequently in somatic cells. Consequently, four different mutation types are formed, including homozygous, heterozygous, bi-allelic and chimeric mutations, with bi-allelic mutations having the highest rate and chimeric mutations having the lowest rate. All, except chimeric mutations, can descend stably into the next generation.

Enhanced sulfur resistance of Ni/SiO2 catalyst for methanation via the plasma decomposition of nickel precursor.

A Ni/SiO2 catalyst was prepared by the plasma decomposition of a nickel precursor via dielectric barrier discharge (DBD). The obtained Ni/SiO2 catalyst shows an enhanced H2S resistance for methanation of syngas (CO + H2). The plasma decomposition has a significant influence on the structural property of Ni/SiO2. The plasma decomposed catalyst shows less defect sites on Ni particles. The formation of Ni-sulfur species was effectively inhibited. The mechanism of H2S poisoning on different catalysts with and without plasma decomposition was also discussed according to the reaction temperature.