Formation of active N–Co(II)–O centers by calcinating cobalt tetraaminophthalocyanine for the elimination of organic pollutants under controllable hydrogen peroxide activation

Abstract Co-based hybrid organic–inorganic heterogeneous catalyst was prepared using cobalt tetraaminophthalocyanine (CoTAPc) as precursor via simple one-pot calcination under oxidizing atmosphere, and characterized by X-ray photoelectron spectroscopy, transmission electron microscopy, X-ray absorption fine spectroscopy, etc. The results showed that the oxygen (O) atom was introduced into the Co(II)–N4 structure of CoTAPc, generating the active N–Co(II)–O centers with novel coordination environment around the ion of cobalt. This heterogeneous Co-based hybrid catalyst exhibits high catalytic activity and sufficient stability for the elimination of organic pollutants by H2O2 activation, even in high backgrounds of complex constituents. Moreover, the controllable H2O2 activation was achieved at relatively low H2O2 dosage under mild condition. The possible mechanism of the heterolytic cleavage of O–O bond during H2O2 activation was proposed, and such different cobalt coordination environment facilitated the formation of high active Co(IV) = O species. Besides, the oxidation pathway of substrates was presented according to the intermediates and the final products detected by ultra-performance liquid chromatography/high-definition mass spectrometry and gas chromatography/mass spectrometry, respectively.