Outwardly, the N1 spectra of the catalysts synthesized

with HSP cancer Cobalt acetate and cobalt nitrate are apparently different from that with cobalt oxalate and cobalt chloride. The peak at about 401 eV is obviously higher than that at about 398 eV for the former, while the height of these peaks selleck is almost the same for the latter. The spectra in Figure 7 have been deconvoluted into various types of nitrogen as shown and the specific concentration of each state of nitrogen is listed in Table 3. The nitrogen distribution in the studied catalysts can be classified into two groups. Similar results have been obtained in the catalysts prepared from cobalt acetate and cobalt nitrate, and closely similar distributions have been exhibited in the catalysts synthesized from cobalt oxalate and cobalt chloride. This is probably

because of the fact that the reconfiguration of the catalyst, especially the decomposition of PPy and the insertion of nitrogen into carbon, during high-temperature pyrolysis could be interfered by the transforming process of cobalt ion in the used precursor into metallic cobalt. When cobalt acetate and cobalt nitrate are used, they thermally decompose under inert atmosphere into cobalt oxide and then metallic cobalt [42–45]. When cobalt oxalate is employed, however, it thermally BKM120 decomposes into metallic cobalt directly [46–48], and the cobalt ion in cobalt chloride is reduced by carbon directly into metallic cobalt [49, 50]. Thus, different states and the corresponding content of nitrogen in the final catalysts have been achieved. As to the correlation selleck compound between the ORR performance of the catalysts and the concentration of each type of nitrogen in the catalysts, neither positive nor negative trend could be found. Therefore, it is difficult at present to expatiate the specific contribution of each type of nitrogen to the ORR catalytic performance of the Co-PPy-TsOH/C catalysts, maybe synergistic

effects exist among them. Figure 7 XPS spectra for N1s core-level peaks in Co-PPy-TsOH/C catalysts prepared from various cobalt precursors. (a) Cobalt acetate; (b) cobalt nitrate; (c) cobalt oxalate; (d) cobalt chloride. Table 3 Surface atomic concentration of different types of nitrogen in Co-PPy-TsOH/C catalysts prepared from various cobalt precursors Cobalt precursor Pyridinic-N Pyrrolic-N Graphitic-N Oxidized-N Cobalt acetate 0.308 0.225 0.279 0.188 Cobalt nitrate 0.297 0.204 0.293 0.207 Cobalt oxalate 0.345 0.305 0.197 0.153 Cobalt chloride 0.355 0.311 0.175 0.159 Figure 8 exhibits content of diverse elements in the Co-PPy-TsOH/C catalysts prepared with various precursors. Comparable carbon contents have been achieved in the studied catalysts. However, the content of other elements differs greatly from each other. Cobalt content in the catalysts prepared with cobalt acetate, cobalt nitrate, and cobalt chloride is obviously higher than the designed value of 10.