Detailed surface vs. bulk composition studies of LaxCa1−xMnO3 oxides provide clear evidence that the ORR activity increases as the effective electron population at the Mn site increases.

Thermal decomposition of citric acid is one of the most common synthesis methods for fluorescent carbon dots; the reaction pathway is, however, quite complex and the details are still far from being understood. For instance, several intermediates form during the process and they also give rise to fluorescent species. In the present work, the formation of fluorescent C‐dots from citric acid has been studied as a function of reaction time by coupling infrared analysis, X‐ray photoelectron spectroscopy, liquid chromatography/mass spectroscopy (LC/MS) with the change of the optical properties, absorption and emission. The reaction intermediates, which have been identified at different stages, produce two main emissive species, in the green and blue, as also indicated by the decay time analysis. C‐dots formed from the intermediates have also been synthesised by thermal decomposition, which gave an emission maximum around 450 nm. The citric acid C‐dots in water show short temporal stability, but their functionalisation with 3‐aminopropyltriethoxysilane reduces the quenching. The understanding of the citric acid thermal decomposition reaction is expected to improve the control and reproducibility of C‐dots synthesis.

No abstract

The electrooxidation of ethanol to acetate is achieved with Rh(I) diolefin amine complexes of the general formula [Rh(Y)(trop 2 NH)(L)] (L ¼ PPh 3 , P(4-n-BuPh) 3 ; Y ¼ triflate, acetate; Bu ¼ butyl) in direct alcohol fuel cells that have the peculiarity of containing a molecular anode electrocatalyst and, hence, are denoted as OrganoMetallic Fuel Cells (OMFCs). Changing the carbon black support from Vulcan XC-72 (Cv) to Ketjenblack EC 600JD (Ck) and/or the axial phosphane to produce non crystalline complexes has been found to remarkably change the electrochemical properties of the organorhodium catalysts, especially in terms of specific activity and durability. An in-depth study has shown that either Ck or P(4-n-butylPh) 3 favour the formation of an amorphous Rh-acetato phase on the electrode, leading to a much more efficient and recyclable catalyst as compared to a crystalline Rhacetate complex which is formed on Cv with PPh 3 as the ligand. The ameliorating effect of the amorphous phase has been ascribed to its higher number of surface complex molecules as compared to the crystalline phase. A specific activity as high as 10 000 A g Rh À1 has been found in a half cell, which is the highest value ever reported for ethanol electrooxidation.

Utilization ofin situ/operandotechniques for establishing the chemical/structural changes induced on Co–Fe spinels that determine their OER durability.