Bi5+ doping improves the electrochemical properties of Ti/SnO2–Sb/PbO2 electrode and its electrocatalytic performance for phenol

Ti/SnO2–Sb/PbO2 is an anode with a good catalytic performance which can be further improved by using metal doping. One of the most potential metals is bismuth (Bi). In this study, Ti/SnO2–Sb/PbO2 and Bi3+ or Bi5+ doped electrodes (Ti/SnO2–Sb/Bi3+-PbO2 and Ti/SnO2–Sb/Bi5+-PbO2) were prepared, and the microscopic morphology and surface chemical compositions of three electrodes were compared. X-ray diffraction results showed that although Bi3+ and Bi5+ doping both inhibited the formation of PbO2 films to a certain extent, Bi5+ doping not only reduced the grain size of PbO2 but also increased more active sites on the electrode surface. The X-ray photoelectron spectroscopy and cyclic voltammetry results found the copresence of Pb2+ and Pb4+ on the surface of the Ti/SnO2–Sb/Bi5+-PbO2 electrode, which could induce superconductivity with better electron transfer ability than the other two electrodes. The electrochemical activities of the three electrodes were analyzed by conducting cyclic voltammetry and linear sweep voltammetry tests, and Ti/SnO2–Sb/Bi5+-PbO2 exhibited the highest catalytic reaction activity with the highest oxygen evolution potential (1.98 V). In the electrocatalytic oxidation experiment of 1100 mg/L phenol by adopting Ti/SnO2–Sb/Bi5+-PbO2, the removal rate within 3 h and the COD removal rate within 30 h could reach 99.65% and up to 95.92%, respectively, with the highest apparent kinetic coefficient of phenol of 0.03040 min−1. Radical scavenging experiments determined that 89% of phenol was removed by electrocatalytically generated •OH oxidation. The energy consumption evaluation of three electrodes revealed that Bi5+-doped electrodes possessed the highest average current efficiency and the lowest energy consumption. This study proposed a new doping option for Ti/SnO2–Sb/PbO2, which provided a reference and theoretical basis for the better application of this electrode in electrocatalysis practice.