Achieving asymmetric redox chemistry for oxygen evolution reaction through strong metal-support interactions

Water electrolysis poses a significant challenge for balancing catalytic activity and stability of oxygen evolution reaction(OER)electrocatalysts.In this study,we address this challenge by constructing asymmetric redox chemistry through elaborate surface OO–Ru–OH and bulk Ru–O–Ni/Fe coordination moieties within single-atom Ru-decorated defective NiFe LDH nanosheets(Ru@d-NiFe LDH)in conjunction with strong metal-support interactions(SMSI).Rigorous spectroscopic characterization and theoretical calculations indicate that single-atom Ru can delocalize the O 2p electrons on the surface and optimize d-electron configurations of metal atoms in bulk through SMSI.The^(18)O isotope labeling experiment based on operando differential electrochemical mass spectrometry(DEMS),chemical probe experiments,and theoretical calculations confirm the encouraged surface lattice oxygen,stabilized bulk lattice oxygen,and enhanced adsorption of oxygen-containing intermediates for bulk metals in Ru@d-NiFe LDH,leading to asymmetric redox chemistry for OER.The Ru@d-NiFe LDH electrocatalyst exhibits exceptional performance with an overpotential of 230 mV to achieve 10 mA cm^(−2)and maintains high robustness under industrial current density.This approach for achieving asymmetric redox chemistry through SMSI presents a new avenue for developing high-performance electrocatalysts and instills confidence in its industrial applicability.

S-doped carbon aerogels/GO composites as oxygen reduction catalysts

Composites of carbon aerogel and graphite oxide（GO） were synthesized using a self-assembly method based on dispersive forces. Their surface was modified by treatment in hydrogen sulfide at 650 and800 ℃. The samples obtained were characterized by adsorption of nitrogen, TA-MS, XPS, potentiometric titration, and HRTEM and tested as catalysts for oxygen reduction reactions（ORR） in an alkaline medium.The synergistic effect of the composite（electrical conductivity, porosity and surface chemistry） leads to a good ORR catalytic activity. The onset potential for the composite of carbon aerogel heated at 800 ℃ is shifted to a more positive value and the number of electron transfer was 2e-at the potential 0.68 V versus RHE and it increased to 4e-with an increase in the negative values of the potential. An excellent tolerance to methanol crossover was also recorded.

Fullerene Mechanochemistry:Serendipitous Discovery of Dumb-Bell-Shaped C_(120) and Beyond

The serendipitous discovery of dumb-bell-shaped C_(120) under high-speed vibration milling conditions is described.The mechanochemical protocol has been employed to synthesize the He-,H_(2)-or H_(2)O-encapsualted C_(120),the cross-dimer C_(130),trimer C_(180),bridged C_(60) dimers as well as products from many other reactions of fullerenes,carbon nanotubes and graphenes.Mechanochemistry extended to various reactions of non-fullerene molecules is briefly discussed.

Theophylline as a new and green catalyst for the one-pot synthesis of spiro[benzo[α]pyrano[2,3-c]phenazine]and benzo[α]pyrano[2,3-c]phenazine derivatives under solvent-free conditions

A green,convenient,high yielding and one-pot procedure for the synthesis of novel spiro[benzo[α]pyrano[2,3-c]phenazine]derivatives by domino multi-component condensation reaction between 2-hydroxynaphthalene-l,4-dione,benzene-l,2-diamines,ninhydrine,and malononitrile in the presence of a catalytic amount of 1,3-dimethyl-7H-purine-2,6-dione（theophylline） as an expedient,eco-friendly and reusable solid base catalyst under thermal,microwave irradiation and solvent-free conditions.This procedure has also been applied successfully for the synthesis of benzo[α]pyrano[2,3-c]phenazines.

Caffeine catalyzed green synthesis of novel benzo[a][1,3]oxazino[6,5-c]phenazines via a one-pot multi-component sequential protocol in a basic ionic liquid

Caffeine was applied as a green and natural catalyst for the one-pot,four-component sequential condensation between 2-hydroxy-1,4-naphthoquinone,aromatic 1,2-diamines,ammonium thiocyanate and acid chlorides in the presence of a basic ionic liquid（l-butyl-3-methylimidazolium hydroxide） to afford the corresponding benzo[a][1,3]oxazino[6,5-c]phenazine derivatives.In this one-pot transformation,five bonds and two new rings are efficiently formed.This protocol has the advantages of operational simplicity,high yields,easy workup,avoidance of hazardous or toxic catalysts and organic solvents and high chemo-and regioselectivities.