The antinociceptive and anti-alpha-glucosidase effects of glucosides from Hemiphragma heterophyllum Wall.

Hemiphragma heterophyllum Wall. is commonly used in traditional Yi herbal medicine for treating bellyache and toothache. In the current study, an unreported monoterpene glucoside, (S)-thymoquinol O-(6-O-oleuropeoyl)-ß-d-glucopyranoside (1), together with 11 known glucosides were obtained from the whole herb of H. heterophyllum. Their structures were determined based on a detailed analysis of spectroscopic data and acid hydrolysis and methanolysis reactions. Bioassay results showed that compounds 1 and 10 at 40 mg/kg exhibited significant antinociceptive activity in the acetic acid-induced writhing model, with inhibitions of 59.80% and 64.07%, respectively. Moreover, five of the isolates showed moderate anti-α-glucosidase activities with IC50 values ranging from 5.67 to 46.16 µM.

1D@2D Hierarchical Structures of Co(OH)x Nanosheets on NiMoOx Nanorods Can Mediate Alkaline Hydrogen Evolution with Industry-Level Current Density and Stability.

Developing efficient electrocatalysts at ampere-scale current densities is of paramount importance to advance industrial applications of alkaline water electrolysis. Herein, a hierarchical nanostructured electrocatalyst with two-dimensional Co(OH)x nanosheets grown on one-dimensional NiMoOx nanorods over three-dimensional porous Ni foam substrate is designed. The resulting catalyst delivers ultrahigh hydrogen evolution reaction (HER) activity in the alkaline solution, which only requires overpotentials of 185 and 332 mV to achieve the current densities of -500 and -1000 mA cm-2 in 1.0 m KOH, respectively, and shows robust stability at -1000 mA cm-2 for 11 days. The unique 1D @ 2D hierarchical structures with abundant hetero-interfaces can not only expose sufficient active sites but also boost alkaline HER kinetics with fast water dissociation ability. This present work may pave a new insight to design efficient electrocatalysts with hierarchical structures for alkaline HER with industry-level current density and stability.

Operando Converting BiOCl into Bi2O2(CO3)xCly for Efficient Electrocatalytic Reduction of Carbon Dioxide to Formate.

Bismuth-based materials (e.g., metallic, oxides and subcarbonate) are emerged as promising electrocatalysts for converting CO2 to formate. However, Bio-based electrocatalysts possess high overpotentials, while bismuth oxides and subcarbonate encounter stability issues. This work is designated to exemplify that the operando synthesis can be an effective means to enhance the stability of electrocatalysts under operando CO2RR conditions. A synthetic approach is developed to electrochemically convert BiOCl into Cl-containing subcarbonate (Bi2O2(CO3)xCly) under operando CO2RR conditions. The systematic operando spectroscopic studies depict that BiOCl is converted to Bi2O2(CO3)xCly via a cathodic potential-promoted anion-exchange process. The operando synthesized Bi2O2(CO3)xCly can tolerate - 1.0 V versus RHE, while for the wet-chemistry synthesized pure Bi2O2CO3, the formation of metallic Bio occurs at - 0.6 V versus RHE. At - 0.8 V versus RHE, Bi2O2(CO3)xCly can readily attain a FEHCOO- of 97.9%, much higher than that of the pure Bi2O2CO3 (81.3%). DFT calculations indicate that differing from the pure Bi2O2CO3-catalyzed CO2RR, where formate is formed via a *OCHO intermediate step that requires a high energy input energy of 2.69 eV to proceed, the formation of HCOO- over Bi2O2(CO3)xCly has proceeded via a *COOH intermediate step that only requires low energy input of 2.56 eV.

Highly Ethylene-Selective Electrocatalytic CO2 Reduction Enabled by Isolated Cu-S Motifs in Metal-Organic Framework Based Precatalysts.

Copper-based materials are efficient electrocatalysts for the conversion of CO2 to C2+ products, and most these materials are reconstructed in situ to regenerate active species. It is a challenge to precisely design precatalysts to obtain active sites for the CO2 reduction reaction (CO2 RR). Herein, we develop a strategy based on local sulfur doping of a Cu-based metal-organic framework precatalyst, in which the stable Cu-S motif is dispersed in the framework of HKUST-1 (S-HKUST-1). The precatalyst exhibits a high ethylene selectivity in an H-type cell with a maximum faradaic efficiency (FE) of 60.0 %, and delivers a current density of 400 mA cm-2 with an ethylene FE up to 57.2 % in a flow cell. Operando X-ray absorption results demonstrate that Cuδ+ species stabilized by the Cu-S motif exist in S-HKUST-1 during CO2 RR. Density functional theory calculations indicate the partially oxidized Cuδ+ at the Cu/Cux Sy interface is favorable for coupling of the *CO intermediate due to the modest distance between coupling sites and optimized adsorption energy.

Boosting Alkaline Hydrogen Evolution Electrocatalysis over Metallic Nickel Sites through Synergistic Coupling with Vanadium Sesquioxide.

For renewable and sustainable energy, developing cut-price and high-efficiency electrocatalysts for the hydrogen evolution reaction (HER) by alkaline water electrolysis is of paramount importance. In this study, a compound electrocatalyst composed of nickel-vanadium sesquioxide nanoparticles supported on porous nickel foam (Ni-V2 O3 /NF) is found to exhibit electrocatalytic performance towards HER that is superior to that of the commercial Pt/C catalyst, with nearly zero onset overpotential, an extremely low overpotential of 25 mV to obtain a current density of -10 mA cm-2 , a Tafel slope of 58 mV dec-1 , and a good durability for 24 h in 1.0 m KOH. Theoretical calculations reveal that the presence of V2 O3 optimizes the electronic structure of active Ni components and continuously accelerates the dissociation of water molecules, which in turn improves the HER kinetics. The present work will advance the development of highly efficient nanocomposite electrocatalysts for alkaline water electrocatalysis.