Influence of MnOx deposition on TiO2 nanotube arrays for electrooxidation

TiO2 has demonstrated outstanding performance in electrochemical advanced oxidation processes(EAOPs)due to its structural stability and high oxygen overpotential.However,there is still much room for improving its electrochemical activity.Herein,narrow bandgap manganese oxide(MnOx)was composited with TiO2 nanotube arrays(TiO2 NTAs)that in-situ oxidized on porous Ti sponge,forming the MnOx-TiO2 NTAs anode.XANES and XPS analysis further proved that the composition of MnOx is Mn2O3.Electrochemical characterizations revealed that increasing the composited concentration of MnOx can improve the conductivity and reduce oxygen evolution potential so as to improve the electrochemical activity of the composited MnOx-TiO2 NTAs anode.Meanwhile,the optimal degradation rate of benzoic acid(BA)was achieved using MnOx-TiO2 NTAs with a MnOx concentration of 0.1 mmol L-1,and the role of MnOx was proposed based on DFT calculation.Additionally,the required electrical energy(EE/O)to destroy BA was optimized by varying the composited concentration of MnOx and the degradation voltage.These quantitative results are of great significance for the design and application of high-performance materials for EAOPs.