Three-Dimensional PbO2-Modified Carbon Felt Electrode for Efficient Electrocatalytic Oxidation of Phenol Characterized with In Situ ATR-FTIR

A three-dimensional (3D) electrode was successfully fabricated by coating carbon felt substrate with PbO2 using an electrodeposition method. Compared with the conventional planar Ti/SnO2–Sb/PbO2 electrode, the CF/PbO2 electrode displayed superior electrocatalytic performance for the degradation of phenol, with an 11.2 times higher rate constant. The improved performance was due to its larger active surface area, enrichment of phenol on the surface due to adsorption, and enhanced mass transfer with the porous 3D structure. It also exhibited an 11.4 times higher current efficiency and a 9.1 times lower energy consumption due to the superior electrocatalytic activity and a higher oxidation potential to hinder oxygen evolution. Moreover, the generation rate of •OH from CF/PbO2 was 1.3 times higher than that of the Ti/SnO2–Sb/PbO2 electrode. The surface chemistry on the CF/PbO2 electrode during phenol degradation was explored by in situ attenuated total reflection–Fourier transform infrared (ATR-FTIR) characterization, with aromatic intermediates and carboxylic acids identified as key reaction intermediates. This composite electrode also presented excellent long-term stability and durability and negligible leaching of Pb cation, demonstrating as a promising electrode for the electrocatalytic degradation of refractory pollution in wastewater treatment.