Boosting Electrocatalytic Ethylene Epoxidation by Single Atom Modulation.

The electrochemical synthesis of ethylene oxide (EO) using ethylene and water under ambient conditions presents a low-carbon alternative to existing industrial production process. Yet, the electrocatalytic ethylene epoxidation route is currently hindered by largely insufficient activity, EO selectivity, and long-term stability. Here we report a single atom Ru-doped hollandite structure KIr4O8 (KIrRuO) nanowire catalyst for efficient EO production via a chloride-mediated ethylene epoxidation process. The KIrRuO catalyst exhibits an EO partial current density up to 0.7 A cm-2 and an EO yield as high as 92.0 %. The impressive electrocatalytic performance towards ethylene epoxidation is ascribed to the modulation of electronic structures of adjacent Ir sites by single Ru atoms, which stabilizes the *CH2CH2OH intermediate and facilitates the formation of active Cl2 species during the generation of 2-chloroethanol, the precursor of EO. This work provides a single atom modulation strategy for improving the reactivity of adjacent metal sites in heterogeneous electrocatalysts.

Coverage-driven selectivity switch from ethylene to acetate in high-rate CO2/CO electrolysis.

Tuning catalyst microenvironments by electrolytes and organic modifications is effective in improving CO2 electrolysis performance. An alternative way is to use mixed CO/CO2 feeds from incomplete industrial combustion of fossil fuels, but its effect on catalyst microenvironments has been poorly understood. Here we investigate CO/CO2 co-electrolysis over CuO nanosheets in an alkaline membrane electrode assembly electrolyser. With increasing CO pressure in the feed, the major product gradually switches from ethylene to acetate, attributed to the increased CO coverage and local pH. Under optimized conditions, the Faradaic efficiency and partial current density of multicarbon products reach 90.0% and 3.1 A cm-2, corresponding to a carbon selectivity of 100.0% and yield of 75.0%, outperforming thermocatalytic CO hydrogenation. The scale-up demonstration using an electrolyser stack achieves the highest ethylene formation rate of 457.5 ml min-1 at 150 A and acetate formation rate of 2.97 g min-1 at 250 A.

Synergistic Catalysis over Iron-Nitrogen Sites Anchored with Cobalt Phthalocyanine for Efficient CO2 Electroreduction.

Simultaneously achieving high Faradaic efficiency, current density, and stability at low overpotentials is essential for industrial applications of electrochemical CO2 reduction reaction (CO2 RR). However, great challenges still remain in this catalytic process. Herein, a synergistic catalysis strategy is presented to improve CO2 RR performance by anchoring Fe-N sites with cobalt phthalocyanine (denoted as CoPc©Fe-N-C). The potential window of CO Faradaic efficiency above 90% is significantly broadened from 0.18 V over Fe-N-C alone to 0.71 V over CoPc©Fe-N-C while the onset potential of CO2 RR over both catalysts is as low as -0.13 V versus reversible hydrogen electrode. What is more, the maximum CO current density is increased ten times with significantly enhanced stability. Density functional theory calculations suggest that anchored cobalt phthalocyanine promotes the CO desorption and suppresses the competitive hydrogen evolution reaction over Fe-N sites, while the *COOH formation remains almost unchanged, thus demonstrating unprecedented synergistic effect toward CO2 RR.

Interfacial Enhancement by γ-Al2 O3 of Electrochemical Oxidative Dehydrogenation of Ethane to Ethylene in Solid Oxide Electrolysis Cells.

Oxidative dehydrogenation of ethane (ODE) is limited by the facile deep oxidation and potential safety hazards. Now, electrochemical ODE reaction is incorporated into the anode of a solid oxide electrolysis cell, utilizing the oxygen species generated at anode to catalytically convert ethane. By infiltrating γ-Al2 O3 onto the surface of La0.6 Sr0.4 Co0.2 Fe0.8 O3-δ -Sm0.2 Ce0.8 O2-δ (LSCF-SDC) anode, the ethylene selectivity reaches as high as 92.5 %, while the highest ethane conversion is up to 29.1 % at 600 °C with optimized current and ethane flow rate. Density functional theory calculations and in situ X-ray photoelectron spectroscopy characterizations reveal that the Al2 O3 /LSCF interfaces effectively reduce the amount of adsorbed oxygen species, leading to improved ethylene selectivity and stability, and that the formation of Al-O-Fe alters the electronic structure of interfacial Fe center with increased density of state around Fermi level and downshift of the empty band, which enhances ethane adsorption and conversion.

Graphene-supported iron-based nanoparticles encapsulated in nitrogen-doped carbon as a synergistic catalyst for hydrogen evolution and oxygen reduction reactions.

Electrolyzers and fuel cells have been extensively investigated as promising solutions for renewable energy storage and conversion. Hydrogen evolution reaction (HER) and oxygen reduction reaction (ORR) are important electrocatalytic processes in electrolyzers and fuel cells. Exploring efficient non-precious metal catalysts for HER and ORR in acidic medium remains a great challenge. Herein, we report that graphene-supported iron-based nanoparticles encapsulated in a nitrogen-doped carbon (Fe@N-C) hybrid material acts as an efficient HER and ORR catalyst. The hybrid material was synthesized by pyrolysis of graphene oxide and ammonia ferric citrate followed by acid-leaching. During the pyrolysis, nitrogen was doped into a graphene lattice, and the carbon nanoshell grown on graphene effectively suppressed the stacking of graphene sheets, exposing more active sites to reactants. The hybrid material showed higher electrocatalytic activities than graphene sheets or Fe@N-C alone, which is probably attributed to the synergetic role of nitrogen-doped graphene and Fe@N-C towards the electrocatalytic reactions.

Iron encapsulated within pod-like carbon nanotubes for oxygen reduction reaction.

Chainmail for catalysts: a catalyst with iron nanoparticles confined inside pea-pod-like carbon nanotubes exhibits a high activity and remarkable stability as a cathode catalyst in polymer electrolyte membrane fuel cells (PEMFC), even in presence of SO(2). The approach offers a new route to electro- and heterogeneous catalysts for harsh conditions.

[Study on the effects of cooking oil fume condensate on the DNA integrity].

The aim of this study was to study the DNA damage mechanisms of cooking oil fumes (COF) in vitro. The colorimetric MTT reduction assay was adopted to measure the effects of the cytotoxicity of COF condensate on type II pneumocytes from the lungs in the rats. The condensate of COF was of the dose-responsive effect on cell-inhibit rate to some extent (r = 0.943, P < 0.01). There is distinctive cytotoxicity on type II pneumocytes when concentration is higher than 20 micrograms/ml. The genotoxicities of COF condensate to type II pnemocytes were studied by modified alkaline single-cell gel using a electrophoresis(SCGE) assay(comet assay), the maximum concentration of condensate is below the concentration of cytotoxicity. The results showed that the condensate of COF was of the dose-responsive effect on the type II pneumocytes DNA damage to some extent(r = 0.918, P < 0.05) at the dosage of 0-5 micrograms/ml. The DNA damage reach to the maximum at the dosage of 10 micrograms/ml. The damaged DNA could be restored after been cultured for 2 hours. Calf thymus DNA cross-link after the administration of COF condensate were measured with ethidium bromide assay. It was found that condensate of COF was of the dose-responsive effect on the calf thymus DNA cross-links to some extent(r = 0.963, P < 0.01). The above results suggested that cooking oil fume condensate could induce DNA damage at much lower dosage and result in the increase of DNA cross-links in a certain concentration.