Co-CoO-Co3O4 Realizes ultra highly sensitive detection of 4-nitrochloro- benzene based on synergistic effect of adsorption and catalysis

Accurate determination of 4-nitrochlorobenzene (4-NCB) concentrations in water environment always keeps its challenge due to the high toxicity and redox inertness of organic pollutants. Herein, cobalt-based oxide nano -materials with different oxidation states were prepared by annealing ZIF-67 under N2 protection and subsequent oxidation in air. The products obtained from non-oxidation, oxidation for 4 and 8 h were named Co, Co-CoO-Co3O4 and Co3O4, respectively. Compared with Co and Co3O4, incompletely oxidized Co-CoO-Co3O4 exhibited the best detection performance for the electroanalytical behavior of 4-NCB, with a high sensitivity of 2.29 mu A mu M-1 in the concentration range of 0.5-4 mu M. The results show that the Co-CoO-Co3O4 composite obtained by Co oxidation for 4 h has a slight decrease in the adsorption capacity of 4-NCB, but its catalytic reduction perfor-mance is improved by about 4 times, and the improvement of catalytic ability makes it have more excellent electrochemical detection performance. It is confirmed that the synergistic effect of adsorption and catalysis affects the electrochemical detection performance of organic pollutants, and the catalytic behavior of the ma-terial is a more critical factor affecting electrochemical detection.