The low oxidation kinetics of alcohols and the need for expensive platinum group metals are still some of the main drawbacks for the commercialization of energy efficient direct alcohol fuel cells. In this work, we investigate the influence of nitrogen doping of ordered mesoporous carbon (CMK) as support on the electrochemical activity of PtRu nanoparticles. Nitrogen doping procedures involve the utilization of pyrrole as both nitrogen and carbon precursor by means of a templating method using mesoporous silica. This method allows obtaining carbon supports with up to 14 wt. % nitrogen, with an effective introduction of pyridinic, pyrrolic and quaternary nitrogen. PtRu nanoparticles were deposited by sodium formate reduction method. The presence of nitrogen mainly influences the Pt:Ru atomic ratio at the near surface, passing from 50:50 on the bare (un-doped) CMK to 70:30 for the N-doped CMK catalyst. The electroactivity towards the methanol oxidation reaction (MOR) was evaluated in acid and alkaline electrolytes. The presence of nitrogen in the support favors a faster oxidation of methanol due to the enrichment of Pt at the near surface together with an increase of the intrinsic activity of PtRu nanoparticles.

In this work, palladium-nickel nanoparticles supported on carbon nanofibers were synthesized, with metal contents close to 25 wt % and Pd:Ni atomic ratios near to 1:2. These catalysts were previously studied in order to determine their activity toward the oxygen reduction reaction. Before the deposition of metals, the carbon nanofibers were chemically treated in order to generate oxygen and nitrogen groups on their surface. Transmission electron microscopy analysis (TEM) images revealed particle diameters between 3 and 4 nm, overcoming the sizes observed for the nanoparticles supported on carbon black (catalyst Pd-Ni CB 1:2). From the CO oxidation at different temperatures, the activation energy Eact for this reaction was determined. These values indicated a high tolerance of the catalysts toward the CO poisoning, especially in the case of the catalysts supported on the non-chemically treated carbon nanofibers. On the other hand, apparent activation energy Eap for the methanol oxidation was also determined finding—as a rate determining step—the COads diffusion to the OHads for the catalysts supported on carbon nanofibers. The results here presented showed that the surface functional groups only play a role in the obtaining of lower particle sizes, which is an important factor in the obtaining of low CO oxidation activation energies.

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In this work, Pd-Ni catalysts supported on carbon nanofibers were synthesized, with metal contents and Pd:Ni atomic ratios close to 25 wt. % and 1:2, respectively.Previously, the carbon nanofibers were chemically treated, in order to create surface oxygen and/or nitrogen groups. The synthesized catalysts displayed low crystallinity degree and high dispersion on carbon supports, especially in those with surface functional groups. Oxygen reduction reaction (ORR) was studied by rotating ring-disk electrode (RRDE) techniques. When the kinetic current is normalized by the mass of Pd present in the electrode, higher activities were obtained for the synthesized materials in comparison with the activity observed for a commercial Pd/C E-TEK catalyst. Some differences are reported for the different materials under study, mainly dependent on the presence of oxygen surface groups on the carbon support. In light of the results, we can propose the synthesized catalysts as possible candidates for cathodes in alkaline direct methanol fuel cells.

The process TiO 2 /PAC/UV-vis has been under study and compared with the isolated treatments of adsorption and photocatalysis determining possible synergies between adsorption and photocatalysis of target antibiotics: amoxicillin, enrofloxacin, sulfadiazine, and trimethoprim. The characterization of the TiO2/PAC mixture was carried out via FESEM and FTIR. Moreover, a kinetic study has been performed. The effect of UV-vis radiation and the type of matrix was analyzed in TiO 2 /PAC/UV-vis process. The performance of this treatment has been monitored during three cycles, evaluating also the regeneration of TiO 2 /PAC mixture by UV-vis light. TiO 2 /PAC/UV-vis process allowed the removal of the antibiotics in the range 90-100% (an average removal of 93% of the initial concentration) after 60 min of treatment. However, only amoxicillin showed a significant synergy applying TiO 2 /PAC/UV-vis process. Regarding matrix effect, no influence of the matrix type (ultrapure water or treated wastewater) was observed. Since PAC tends to be deactivated gradually, the TiO 2 /PAC/UV-vis process performance decreases after each cycle in a 15% average. Finally, regeneration via UV-vis light started to be effective after a total of 4 h of regeneration.Keywords TIO 2 -UV/vis photocatalysis . Antibiotic . Powered activated carbon (PAC) * Samuel Moles