Co3O4-280 sample together with minor cobalt hydroxyl–carbonatephase.The XPS spectra of the Co2p, O1sand C 1s electronic levels ofCo3O4-700 sample are shown in Fig. 13. The deconvoluted spectraof these levels reveal the presence of the same peaks observed in thespectra of Co3O4-280 sample, suggesting the surface of the Co3O4-700 sample comprises the same species identified for Co3O4-280one. The spectra for both samples differ only in the peak inten-sities and some peaks show a slight shift in their positions. Thequantification of each surface cobalt, oxygen and carbon specieswas calculated and obtained results are listed in Table 2. Appar-ently, Co3O4-280 sample contains higher Co2+and a lower cobalthydroxyl–carbonate surface concentration than Co3O4-700. Thisfinding, together with the information abstracted from the TEManalysis, suggests a different catalytic behavior of both preparedCo3O4samples in reactions like direct N2O decompositions, whichis greatly influenced by the catalyst particle size and Co2+surfaceconcentration