Copper-mediated activation of persulfate (PS) has been widely investigated for the degradation of refractory organic pollutants . However, the dispersion of the active copper sites in the catalysts remains a great challenge. Herein, a series of well-dispersed Cu-Cu x O embedded into carbon matrix composites (Cu-Cu x O@C) were fabricated via the pyrolysis of HKUST-1 precursor. The Cu-Cu x O@C catalysts were fully characterized by SEM, HRTEM, XRD, BET, Raman, FT-IR, and XPS. The results show that the Cu-Cu x O@C calcinated at 700 °C (Cu-Cu x O@C-700) contained multivalent Cu components. Their heterogeneous activation of PS for phenol degradation was also investigated. Cu-Cu x O@C-700 removed completely phenol with a k obs value greater than 0.40 min −1 . Such superior catalytic activity is mainly attributed to the synergistic effect of carbon matrix adsorption and multivalent Cu active site electron transfer. The reusability studies reveal that the performance of the used Cu-Cu x O@C-700 could be reactivated through re-calcination. Moreover, quenching tests and EPR analyses revealed that OH and SO 4 − are involved in phenol degradation. The electron transfer process and resistance of Cu-Cu x O@C-700 were described by electrochemical method. Finally, the catalytic mechanism was explored by XPS, FT-IR and Raman analyses. This study provides new insights into the fabrication of heterogeneous catalysts for sulfate radical activiation.
Han Sun,Haiping Huang,Chao Hu,Yu Yan,Yongmei Hu,Shengda Guo,Jing-Lin Chen
Cu-Ni oxide nanocomposite was synthesized via solvothermal method with nickel (II) nitrate and copper nitrate as Ni and Cu resource respectively. AuNPs/oxide nanocomposite was obtained by dispersing the oxide into the pre-synthesized Au colloid. Transmission electron microscope (TEM) shows that the synthesized oxides are nanoplate morphology. Interplanar distance from the high resolution TEM (HRTEM) image shows that the Ni and Cu in the oxide are multivalent state. X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) characterization further proves that the Ni and Cu are multivalent state, and the Au is Au 0 form in the nanocomposte. EDS-mapping images confirm large numbers of AuNPs are uniformly absorbed onto the ultra-thin multivalent Cu-Ni oxide nanoplate. The electrochemical properties of multivalent oxide (m-v oxide) with or without AuNPs decoration are investigated in 0.1 M potassium chloride electrolyte with 2.0 mM Ferri/Ferro-Cyanide. When employed for the electrochemical catalysis in methanol oxidation reaction (MOR), the AuNPs/m-v oxide exhibits better electrochemistry performance than m-v oxide. The current density of AuNPs/m-v oxide (21.1 mA/cm 2 ) is 3.4 times bigger than that of m-v oxide/GCE (6.2 mA/cm 2 ). What’s more, it shows good electrochemical stability and lower slope of the Tafel plot (41.87 mV/dec).
Zehui Fan,Zhisen Li,Dan Mo,Jingyang Zhang,Shuyi Yang,Yun Li,Changlong Bi,Chong Peng,E Tao
Modulation of nano electrocatalysts for targeted excitation of different reactive oxygen species (ROS) is a key challenge to achieve environmentally catalyzed efficient pollutant degradation. In this study, multivalent copper catalysts (Cu (0)/Cu (I)/Cu (II)) load on the surface of biochar (CBX) are prepared by the hydrothermal-impregnation method, and the modulation effect of different valences of copper on the pathway of reactive oxygen species (ROS) generation is investigated. X-ray diffraction (XRD) analysis shows the coexistence of three copper valence states. Radical scavenging experiment and DFT calculations indicate that Cu (I) dominates the adsorption and activation of peroxodisulfate (PS) to efficiently generate ·SO 4 - and ·OH. Cu (II) selectively generates 1 O 2 by modulating the dissolve oxygen conversion pathway; whereas Cu (0) acts as an activation center for bound oxygen and significantly promotes ·O 2 - generation. The nano-electrocatalytic system prepared at 600°C (CB6-PS) degraded 98.3% of enrofloxacin (ENR) over a period of time (60 min). Mechanistic studies indicate that the catalytic system realizes the coupling reaction between the radical pathway (·SO 4 - /·OH /·O 2 - ) and the nonradical pathway ( 1 O 2 ) by the synergistic action of multivalent copper, which providing a new theoretical basis and technical strategy for the development of targeted ROS generation function.
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