Grain boundary and interface interaction of metal (copper/indium) oxides to boost efficient electrocatalytic carbon dioxide reduction into syngas.

Electrochemical conversion of carbon dioxide (CO2) into syngas is considered a promising approach to mitigate global warming and achieve the recycling of carbon resources. In this work, a series of core-shell metal (copper/indium) oxides with abundant grain boundaries (GBs) between the amorphous In2O3 and cubic Cu2O have been prepared by template-assisted co-precipitation method and tested for the synthesis of syngas by electrochemical CO2 reduction reaction (CO2RR). The phases of Cu2O and In2O3 are independent in bimetallic oxides and do not form any alloy oxidation phase, thus Cu2O and In2O3 can maintain their crystal structure and chemical properties in bimetallic oxides. The Cu2O and In2O3 would been completely reduced to metallic Cu and In during CO2RR. The derived copper/indium possesses the maximum FE of CO (80 %) at -0.77 V vs. reversible hydrogen electrode (RHE) and a good stability of 10 h in an H-type cell. Further applied the copper/indium oxide in the MEA reactor, the FE of CO is more than 80 % at 2.6 V and the total FE of syngas is near 100 % at all applied potentials. More importantly, the H2/CO ratios can be tuned from 1/1 to 1/4 by changing the applied voltages in MEA. Therefore, this study provides a promising strategy to promote the electrocatalytic CO2RR conversion by creating abundant grain boundaries in bimetallic oxides to regulate the ratio of H2/CO.

Probiotic-fermented Qushi decoction alleviates reserpine-induced spleen deficiency syndrome by regulating spleen function and gut microbiota dysbiosis.

BACKGROUND: Spleen deficiency syndrome (SDS) is associated with elevated inflammatory factors and dysregulation of gastrointestinal motility hormones and intestinal microbiota. Qushi decoction (QD), a traditional formula, has not been reported using modern scientific research methods for changes in its probiotic fermented QD (FQD) composition and its potential mechanisms to alleviate SDS. Therefore, the aim of this study was to investigate the splenic protection of FQD in SDS rats by modulating gastrointestinal motility hormones and intestinal microbiota. RESULTS: The results showed that FQD increased total polysaccharides, total protein, total flavonoids and the other active ingredients compared to QD, effectively improved splenic inflammation and apoptosis in SDS rats, and modulated gastrointestinal motility hormones to alleviate diarrhea and other symptoms. In addition, the dysregulation of the gut microbiota was reversed by increasing the levels of Bifidobacterium and decreasing the levels of Escherichia-Shigella and Proteobacteria, which may be related to the regulation of bacterial metabolites to alleviate SDS. CONCLUSION: These results suggest that FQD is an effective formula for improving SDS. Our findings show that FQD beneficial to the implications for the treatment of SDS. © 2023 Society of Chemical Industry.

CuBi electrocatalysts modulated to grow on derived copper foam for efficient CO2-to-formate conversion.

Electrochemical reduction of CO2 to fuels and chemicals is an effective way to reduce greenhouse gas emissions and alleviate the energy crisis, but the highly active catalysts necessary for this reaction under mild conditions are still rare. In this work, we grew CuBi bimetallic catalysts on derived copper foam substrates by co-electrodeposition, and then investigated the correlation between co-electrodeposition potential and electrochemical performance in CO2-to-formate conversion. Results showed that the bimetallic catalyst formed at a low potential of - 0.6 V vs. AgCl/Ag electrode achieved the highest formate Faradaic efficiency (FEformate) of 94.4% and a current density of 38.5 mA/cm2 at a low potential of - 0.97 V vs. reversible hydrogen electrode (RHE). Moreover, a continuous-flow membrane electrode assembly reactor also enabled the catalyst to show better performance (a FEformate of 98.3% at 56.6 mA/cm2) than a traditional H-type reaction cell. This work highlights the vital impact of co-electrodeposition potential on catalyst performance and provides a basis for the modulated growth of bimetallic catalysts on substrates. It also shows the possibility of preparing Bi-based catalysts with no obvious decrease in catalytic activity that have been partially replaced with more economic copper.

Metal-Nitrogen-Carbon Catalysts of Specifically Coordinated Configurations toward Typical Electrochemical Redox Reactions.

Metal-nitrogen-carbon (M-N-C) material with specifically coordinated configurations is a promising alternative to costly Pt-based catalysts. In the past few years, great progress is made in the studies of M-N-C materials, including the structure modulation and local coordination environment identification via advanced synthetic strategies and characterization techniques, which boost the electrocatalytic performances and deepen the understanding of the underlying fundamentals. In this review, the most recent advances of M-N-C catalysts with specifically coordinated configurations of M-Nx (x = 1-6) are summarized as comprehensively as possible, with an emphasis on the synthetic strategy, characterization techniques, and applications in typical electrocatalytic reactions of the oxygen reduction reaction, oxygen evolution reaction, hydrogen evolution reaction, CO2 reduction reaction, etc., along with mechanistic exploration by experiments and theoretical calculations. Furthermore, the challenges and potential perspectives for the future development of M-N-C catalysts are discussed.

Cu/S-Occupation Bifunctional Oxygen Catalysts for Advanced Rechargeable Zinc-Air Batteries.

The design and synthesis of low-cost and highly efficient bifunctional catalysts is an inevitable path for rechargeable zinc-air batteries (rZABs). In this work, double-carbon co-supported Co-based oxide with the Cu and S substitutions are synthesized by a one-step hydrothermal method and formed a unique honeycomb structure. As expected, the (Cu, Co)3OS3@CNT-C3N4 exhibits high oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) activity with low overpotential (0.86 V), high power density (215 mW cm-2), and long-term discharge stability (115 h). The (Cu, Co)3OS3@CNT-C3N4-based rZAB also shows a stronger charge-discharge durability with a very low voltage gap of merely 0.5 V than that of Pt/C+RuO2. The high catalytic performances are attributed to these following reasons: (i) the porous morphology and hierarchical structure with plentiful "catalytic buffer", which accelerates the mass transfer; (ii) a high-speed electronic transmission network established by C3N4 and carbon nanotube (CNT), enhancing the conductivity; (iii) the strong synergistic effect between (Cu, Co)3OS3@CNT and C3N4, which improves the kinetics of ORR/OER; and (iv) the controllable occupation of Cu ions and S ions, which effectively regulates the CoO6 surface and increases the active site density. This work not only offers a promising ORR/OER electrode for rZAB but also provides a new pathway to understand the improvement mechanism for catalysts by the bi-ion substitutions.

Alkaline Exchange Polymer Membrane Electrolyte for High Performance of All-Solid-State Electrochemical Devices.

As a potential solution to ubiquitous energy concerns, anion-exchange membranes (AEMs) have been widely used as the electrolyte in alkaline fuel cells (AFCs), and significant refinement of AEMs has been achieved in the past few decades. However, it remains unknown whether AEMs can be used as an electrolyte in a solid-state supercapacitor or zinc-air battery. A low-cost alkaline exchange membrane electrolyte composed of chitosan and poly(diallyldimethylammonium chloride) that possesses a high OH- conductivity (0.024 S cm-1), strong alkaline stability (216 h at 8 M KOH), good thermal stability, and low degree of anisotropic swelling, was found to provide a high electrochemical performance in all-solid-state devices. Prototypes of the solid AFC with the membrane shows superior stability over 500 h. The carbon nanotube-based all-solid-state supercapacitor with the membrane generated a rectangular cyclic voltammetry curve up to 10 V s-1 and excellent cycling stability of 4000 cycles with 84% specific capacitance retention. The all-solid-state zinc-air battery demonstrates high power density (48.9 mW cm-2). These advantages indicate that the membrane is a promising electrolyte for all-solid-state electrochemical devices.

Superior stability of a bifunctional oxygen electrode for primary, rechargeable and flexible Zn-air batteries.

Central to commercializing metal-air batteries is the development of highly efficient and stable catalysts for the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). In this study, a composite catalyst with a unique interpenetrating network (denoted as NiCo2O4@MnO2-CNTs-3) was synthesized and exhibited better bifunctional activity (ΔE = 0.87 V) and durability than both Pt/C and Ir/C catalysts. The improved performance arises from three factors: (i) MnO2 promotes the ORR while NiCo2O4 facilitates the OER; (ii) carbon nanotubes improve the electronic conductivity; and (iii) the highly porous structure enables the adsorption-desorption of O2 and enhances the structural stability. As a result, the primary and rechargeable Zn-air battery affords a high power density and specific capacity (722 mA h g-1), an outstanding discharge stability (255 mW cm-2 after 1000 cycles) and a high cycling stability (over 2280 cycles). Electron microscopy and electrochemical analysis revealed that the degradation of the rechargeable Zn-air battery performance resulted from the damage of the air electrode and the hydrogen evolution reaction on the zinc electrode. A flexible Zn-air battery employing a solid-state electrolyte showed an exciting stability (540 cycles) and high power density (85.9 mW cm-2), suggesting that the anion exchange membrane effectively prevents the migration of Zn2+ ions and the deposition of carbonates.