In-situ synthesis of highly dispersed Cu-CuxO nanoparticles on porous carbon for the enhanced persulfate activation for phenol degradation

Abstract

The study reported a straight route to prepare multivalent Cu and carbon composite catalysts with good Cu dispersion serving as copper-base catalysts for sulfate radical-advanced oxidation processes. The proposed copper-base catalysts exhibit excellent degradation efficiency toward refractory organic pollutants. • Multivalent copper coexisted composites were synthesized through a facile method. • Cu-Cu x O were well dispersed on carbon substrates. • The Cu-Cu x O@C composite presented superior catalytic activity in PS activation. • The maximum removal efficiency of phenol reached approximately 100%. 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.