| MATERIALS AND SUSTAINABLE DEVELOPMENT: ADVANCED MATERIALS FOR CLEAN ENERGY UTILIZATION | 
									
										
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    					| Effect of Anionic Groups of Cobalt Salt on the Electrocatalytic Activity of Co-N-C Catalysts | 
  					 
  					  										
						| Yimeng XIA1,Shuai WU1,Feng TAN1,Wei LI1,Qingmao WEI1,Chungang MIN2,Xikun YANG1,2
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						1 College of Material Science and Engineering, Kunming University of Science and Technology, Kunming 650093 2 Research Center for Analysis and Measurement, Kunming University of Science and Technology, Kunming 650093 | 
					 
										
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													     		                            						                            																	    Abstract   During the process of the aniline polymerization, bivalent cobalt salt with different anionic groups such as (C2H3O2)22-, Cl22-, (NO3)22-, SO42- and C2O42- were added into the solution and then different polyaniline cobalt (PANI-Co) coordination polymer were obtained. Finally, Co-N-C catalysts were prepared through pyrolysis of PANI-Co coordination polymer. The morphology, structure, chemical composition and chemical valence of the Co-N-C catalysts were characterized by scanning electron microscopy (SEM), X-ray spectroscopy (XRD), X-ray photoelectron spectroscopy (XPS) and Raman spectra (Raman). The electrocatalytic activity of Co-N-C catalysts were tested by electrochemical method. The results showed that the cobalt salt anionic groups had little impact on the morphology of Co-N-C catalysts, but had a great influence on the composition and surface chemistry of Co-N-C catalysts, carbon structure, degree of graphitization and the valence of Co. The cobalt salt anionic groups could affect the electrocatalytic activity of Co-N-C catalysts. The catalytic activities decreased as (C2H3O2)22->Cl22->(NO3)22->SO42->C2O42-. The Co-N-C catalysts prepared by cobalt salt containing (C2H3O2)22- and Cl22- anions had higher ORR activity, which possibly due to the higher content of graphite nitrogen and pyridine nitrogen.  
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															    															    															    																	Published: 10 February 2018
															    																																	Online:  2018-02-10
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														XRD patterns of different Co-N-C catalysts
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														The SEM images of different Co-N-C catalysts:(a)Co-N-C/C4H6CoO4,(b)Co-N-C/CoCl2,(c)Co-N-C/CoSO4,(d)Co-N-C/Co(NO3)2,(e)Co-N-C/CoC2O4
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																	   | Sample |  C 1s/% |  N 1s/% |  O 1s/% |  S 2p/% |  Co 2p/% |  Co 2p/eV |       | Co-N-C/C4H6CoO4 |  81.41 |  1.85 |  16.08 |  0.27 |  0.39 |  779.12 |     | Co-N-C/CoCl2 |  81.72 |  2.39 |  15.13 |  0.15 |  0.61 |  779.25 |     | Co-N-C/Co(NO3)2 |  83.21 |  2.34 |  13.98 |  0.08 |  0.39 |  779.65 |     | Co-N-C/CoSO4 |  82.49 |  1.84 |  15.23 |  0.13 |  0.32 |  779.60 |     | Co-N-C/CoC2O4 |  56.95 |  1.84 |  29.36 |  2.97 |  8.87 |  778.69 |      
																	 
																 
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														XPS results of the surface element analysis of Co-N-C
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														The XPS spectra of N 1s region for different Co-N-C catalysts
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														The XPS spectra of Co 2p region for different Co-N-C catalysts
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														Raman spectra of different Co-N-C catalysts
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														CV curves of different Co-N-C catalysts
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														LSV curves of different Co-N-C catalysts
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														The different Co-N-C catalysts in O2-saturated 0.5 mol/L H2SO4 solution at 1 500 r/min
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																	   | Sample |  n |       | Co-N-C/C4H6CoO4 |  3.54 |     | Co-N-C/CoCl2 |  3.85 |     | Co-N-C/Co(NO3)2 |  3.90 |     | Co-N-C/CoSO4 |  3.63 |     | Co-N-C/CoC2O4 |  2.21 |      
																	 
																 
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														The n value of ORR of different Co-N-C catalysts at 0.25 V electrode potential
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														LSV curves at different rotation speed and the corresponding K-L plots for Co-N-C/C4H6CoO4 in O2-saturated 0.5 mol/L H2SO4
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