Effect of multi-walled carbon nanotubes addition on MnOx/Ti electrode prepared by spraying–calcination method for electro-catalytic oxidation of Acid Red B

The titanium-based electrodes with MnOx nanoparticles coating (MnOx/Ti) and MnOx nanoparticles mixed with multi-walled carbon nanotubes (MnOx–CNTs/Ti) were fabricated by spraying–calcination method. The physicochemical properties of electrodes were investigated by SEM, XRD and XPS, which indicated that the surface coating of MnOx–CNTs/Ti, with MnOx nanoparticles dispersed uniformly on the CNTs, was smoother and with higher integrity than MnOx/Ti. Acid Red B was used as model pollutant to investigate the electro-catalytic activity of the electrodes, and the results revealed that the removal efficiency of Acid Red B reached 93.6% and 98.0% by MnOx/Ti and MnOx–CNTs/Ti, respectively, and the cell potential during the process of degradation by MnOx–CNTs/Ti was relatively low and stable. The electrochemical results confirmed that MnOx–CNTs/Ti possessed smaller charge transfer resistance and higher oxygen evolution current compared with MnOx/Ti, which can enhance the electro-catalytic activity and reduce the energy consumption by accelerating the transfer of electrons on the electrode surface. The accelerated lifetime tests of electrodes were carried out and showed that actual service lifetimes of MnOx–CNTs/Ti were 38 times of that for MnOx/Ti calculated by the experienced formula, which demonstrated that the durability of MnOx-based electrode was significantly promoted by addition of CNTs on Ti substrate.