Transformation
of carbon dioxide (CO2) into valuable
chemicals is of great importance, and development of novel and efficient
catalysts is crucial. Herein, we found that the renewable lecithin
could be used as an efficient organocatalyst for the formylation and
methylation of various amines with CO2 to corresponding
formamides and methylamines via the construction of new C–N
bonds using PhSiH3 as the hydrogen source, and satisfactory
yields could be obtained. More importantly, the selectivity of the
products could be easily controlled by the molar ratio of reactants
(i.e., CO2, amines, and PhSiH3) and reaction
temperature. In the catalytic cycle, formamides and methylamines were
generated by converting the carbon (+4) in CO2 into +2
and −2 via 2-electron and 6-electron reduction pathway, respectively.
The effects of processing parameters on phase formation of hydrothermally synthesized bismuth ferrites were investigated. Bi 25 FeO 40 , BiFeO 3 , and Bi 2 Fe 4 O 9 with different morphologies and grain size were synthesized by dissolving bismuth nitrate and iron nitrate in KOH solution at reaction time ranging from 3 to 20 h. The subcrystallized part of BiFeO 3 obtained with reaction time of 4 and 5 h displayed strong saturation magnetization of~2.914 emu/g. The results of the electron spin resonance (ESR) indicated each unpaired spin providing a net magnetic moment which eventually led to the enhancement of the saturated magnetization. Furthermore, Zero-field-cooled (ZFC) and field-cooled (FC) magnetization curves exhibited spin-glass freezing behavior in all the samples. And the lowtemperature magnetic hysteresis loop displayed the ferromagnetism of BiFeO 3 with different structures and the phenomenon of exchange bias, respectively.
An electrochemical advanced oxidation process (EAOP) is demonstrated with a catalytic cathode capable of simultaneously catalyzing the hydrogen evolution reaction (HER) and the oxygen reduction reaction (ORR) with resultant in situ generation of atomic hydrogen (H*) and hydrogen peroxide (H 2 O 2 ). A palladiumcoated carbon-PTFE gas diffusion electrode (Pd/C GDE) was used as a catalytic cathode with hydroxyl radical ( • OH) formed as a result of the reaction of electrogenerated H* with H 2 O 2 . As both the HER and ORR can be induced to occur at the same cathode, the H*/GDE process results in more effective degradation of organic contaminants than can be achieved by a conventional H*/H 2 O 2 process involving direct addition of H 2 O 2 . At circumneutral pH, 82.7% of added formate was degraded after 2 h treatment at an applied potential of −1.0 V vs Ag/AgCl with relatively low concentrations of generated H 2 O 2 remaining in the solution. We also show that H* and H 2 O 2 (and thus • OH) can be electrogenerated effectively over a wide range of pH (3.2−7.0). These results suggest that by in situ generation of H* and H 2 O 2 , the H*/GDE process is able to produce significant amounts of • OH without external chemical addition and thus offers an alternative method for abatement of aqueous organic contaminants.
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