The synergetic effect of an aqua ligand and metal site on the performance of single-atom catalysts in H2O2 synthesis: a density functional theory study.

Studying the effect of the coordination field on the catalytic property is critical for the rational design of outstanding electrocatalysts for H2O2 synthesis. Herein, via density functional theory (DFT) calculations and ab initio molecular dynamic (AIMD) simulations, we built an effective computational framework to identify the synergetic effect of an aqua ligand and metal ion on the 2e- ORR catalytic performance under gas condition and aqua solvent. Specifically, the screening results of 29 single-atom catalysts (SACs), TM@C6N6 (TM = transition metal), indicated that Cu@C6N6 features excellent catalytic property with thermal stability, lowest 2e- ORR overpotential (0.02 V) and high selectivity of 99.99%. Once an aqua ligand binds with the Cu site, the activity is reduced to the overpotential of 0.42 V and the selectivity decreased slightly (99.98%) due to the reduction of the adsorption strength for the reaction intermediates. A combination of geometric structures and electronic properties revealed that such changes are correlated with the charge of the Cu site. Furthermore, based on molecular orbital theory, the essence of the high catalytic property deeply lies in the effect of the moderate electron back donation bond (dyz & dxz→) between Cu and O2. This work will provide a route to better design high-performance SACs for H2O2 synthesis effectively.

Highly Robust Tetranuclear Cobalt-Based 3D Framework for Efficient C2H2/CO2 and C2H2/C2H4Separations.

A novel noninterpenetrated tetranuclear cobalt(II)-based metal-organic framework, (NH4)2·[Co4(µ3-OH)2(ina)2(pip)3]·4EtOH·H2O (simplified as NbU-10·S), constructed by mix linkers was synthesized by a hydrothermal method. Interestingly, the presence of a hydrophobic benzene ring in the organic linker makes NbU-10·S exhibit high stability in high temperature and even in aqueous solution over a wide pH range of about 4-13. Magnetic studies showed that the tetranuclear cobalt(II) units in NbU-10·S show dominant antiferromangetic properties. However, in the absence of Lewis basic functional sites and open metal sites in the material, NbU-10 still displays high C2H2/CO2 and C2H2/C2H4 selectivity in ideal adsorbed solution theory calculations and dynamic breakthrough experiments. Moreover, density functional theory calculations were performed to identify the adsorption characteristics of different gas molecules.

7-Connected FeIII3-Based Bio-MOF: Pore Space Partition and Gas Separations.

We reported herein a new 3D bio-MOF (NbU-12) using a pore space partition strategy: MIL-88D was selected as a primary framework, and adenine connected two independent MIL-88D to form a self-interpenetrated structure. Because of this, the hexagonal channel in MIL-88D split into two small rectangular channels. Different from the reported series CPM-35 materials, NbU-12 simultaneously maximized the retention of open metal sites from MIL-88D and introduced a Watson-Crick face to the pore surface of NbU-12. Remarkably, NbU-12 exhibits an excellent selectivity performance toward C2H6/C2H4 and C2H6/CH4, which was proven by ideal adsorbed solution theory calculation and breakthrough experiments.

High-performance single-atom Ni catalyst loaded graphyne for H2O2 green synthesis in aqueous media.

The electrochemical synthesis of hydrogen peroxide (H2O2) provides a greener and more efficient method compared with classic catalysts containing toxic metals. Herein, we used first-principles density functional theory (DFT) calculations to investigate 174 different single-atom catalysts with graphyne substrates, and conducted a three-step screening strategy to identify the optimal noble metal-free single atom catalyst. It is found that a single Ni atom loaded on γ-graphyne with carbon vacancies (Ni@V-γ-GY) displayed remarkable thermodynamic stability, excellent selectivity, and high activity with an ultralow overpotential of 0.03 V. Furthermore, based on ab-initio molecular dynamic and DFT calculations under the H2O solvent, it was revealed that the catalytic performance for H2O2 synthesis in aqueous phase was much better than that in gas phase condition, shedding light on the hydrogen bond network being beneficial to accelerate the transfer of protons for H2O2 synthesis.

[Clinical study of effect of tianzhi granule on senile vascular demetia].

OBJECTIVE: To investigate the clinical effect of Tianzhi Granule (TZK) on senile vascular dementia (VaD), which is classified as sthenia of liver-yang. METHOD: Two hundred VaD patients were treated with TZK (0.5 g/bag), which was taken one bag each, three times a day. The treatment course was one month and they were treated for rwo courses. RESULT: TZK could remarkably increase gnosia and activity, with no striking difference from that of positive control group (P > 0.05). Simultaneously, TZK could significantly improve the clinical syndrome of traditional Chinese medicine and viability. It could also drastically reduce the whole blood and plasma viscosity and improve erythrodegeneration and abnormality of aggregation index in the abnormal blood viscosity patients. CONCLUSION: TMC has certain effects on senile VaD.