Correlation Between Oxygen Reduction Reaction and Oxidative Dehydrogenation Activities Over Nanostructured Carbon Catalysts

Abstract

Nitrogen containing nano-structured carbon catalysts were grown on Fe/Al 2 O 3 and Ni/Al 2 O 3 supports using acetonitrile pyrolysis. The post-pyrolysis samples were tested for activity in the oxygen reduction reaction (ORR) and oxidative dehydrogenation (ODH) reaction. Samples were characterized using BET, XPS and TEM. The samples grown over iron containing supports gave the highest activity in both reactions. There was a strong correlation between ODH and ORR activity suggesting the possibility of a common active site between reactions with the quinone/hydroquinone group being a possible candidate. XPS analysis supported this hypothesis showing that catalysts with a higher percentage of oxygen in the form of quinones tend to have the highest ORR and ODH activity. XPS analysis also demonstrated that samples with higher pyridinic nitrogen content, which is a marker for edge plane exposure and may be a part of the ORR active site, gave higher ORR and ODH activity. TEM images confirm that samples with high pyridinic nitrogen content tend to form structures with higher edge plane exposure. Because the active site, regardless of its identity, likely lies on the graphitic edge plane, this leaves the possibility that a common active site is not necessary to explain the correlation between ODH and ORR activity.

Networked Graphitic Structures as Durable Catalyst Support for PEM Electrodes

“…ysis of the cyclic voltammograms, part of these defects consist of quinone groups on the surface, that in previous studies were found to improve ORR or even to be the active catalyst for it [31]. However, the quantity of defects found is lower than for example in Vulcan XC72 (0.94) which we analyzed as a representative of commercial support since for the one used in HISPEC 9100, named Carbon ACO1 by the supplier, no data were available.…”

One-dimensional nitrogen-containing carbon nanostructures

“…[534]. Similarly, NCNFs containing a range of nitrogen contents of 1−10 atom % were directly synthesized by catalytic CVD over nickelbased catalysts at 350−600 °C using CH 3 CN and acrylonitrile as a CN x source [535].…”

Nitrogen-doped metal-free carbon catalysts for aerobic oxidation of xanthene

“…Similarly, the N 1s spectrum revealed the presence of pyridine-type N (398.5 eV), N(1), and pyrrole-/pyridone-type N (400.5 eV), N(2) (Scheme 2) [17][18][19][20]. Table 1 however, such trend was not significant for the N-doping with NO.…”

“…Typical XPS spectra in the O 1s and N 1s regions are depicted in Figure 1. The O 1s spectrum could be deconvolved into two peaks at 531.8 and 533.3 eV attributed to O species of C=O, O(1), and of C-O-C, O(2), respectively [16,17].…”