Effect of matrix on the electrochemical characteristics of TiO_2 nanotube array-based PbO_2 electrode for pollutant degradation

摘要

A series of lead dioxide electrodes developed on titania nanotube arrays with different matrix were fabricated by electrodeposition. Before the deposition of PbO_2, the matrix of this anode was electrochemically reduced in (NH_4)_2SO_4 solution and/or pre-deposited with certain amounts of copper. To gain insight into these pretreatments, the PbO_2 electrodes were characterized by SEM, LSV, and XRD, and their electrocatalytic activities for pollutant degradation were compared using p-nitrophenol (p-NP) as a model. It was confirmed that the electrochemical reduction with (NH4)2SO_4 resulted in the partial conversion of TiO_2 into Ti_4O_7 and Ti_5O_9, which increased the conductivity of PbO_2 anode, but decreased its electrochemical activity, while the Ti/ TNTs*-Cu/PbO_2 electrode with both pretreatments possessed the highest oxygen evolution overpotential of 2.5 V (vs. SCE) and low substrate resistance. After a 180-min treatment on this electrode, the removal efficiency of p-NP reached 82.5 % and the COD removal achieved 42.5 % with the energy consumption of 9.45 kWh m~(-3), demonstrating the best performance among these electrodes with different matrices. Therefore, this titania nanotube array-based PbO_2 electrode has a promising application in the industrial wastewater treatment.