A novel ternary Ti-V-Bi oxide photoelectrocatalyst in advanced oxidation process

Abstract

Photoelectrocatalytic pollutant degradation is one of the most promising advanced oxidation processes for wastewater treatment. However, its efficiency dramatically depends on the development of photoelectrocatalyst materials. Therefore, here, ternary Ti0.2-Vx-Bi(0.8−x)-oxides (x = 0.15, 0.3, 0.4, 0.5, and 0.65) were applied as the photoelectrocatalysts for pollutant degradation. The photoelectrocatalysts were synthesized by a dip-coating thermal decomposition (DCTD) method. The physical and optical characteristics of photoelectrocatalysts were analyzed by XRD, FE-SEM, EDS, PL, and DRS tests. The photo/electrochemical behavior of samples was studied by LSV, EIS, and chronoamperometry with and without visible light illumination. The activity of samples was investigated by photocatalytic, electrocatalytic, and photoelectrocatalytic treatment of methyl orange and rifampin solutions under visible light irradiation. The kinetics of photocatalytic, electrocatalytic, and photoelectrocatalytic degradation processes was investigated by the Langmuir-Hinshelwood (L-H) kinetic model. Moreover, the mineralization extent of rifampin was studied by COD test. The results pointed to the optimum composition of ternary Ti0.2V0.4Bi0.4-oxide, in terms of both photocurrent and degradation time, which could completely degrade methyl orange and rifampin solutions in less than 15 min at a current density of 5 mA/cm2 under visible light irradiation. The superior performance of Ti0.2V0.4Bi0.4-oxide was attributed to its smaller particle size (larger surface area), lower band gap (2.1 eV), the lower recombination rate of e-/h+ pairs, and lower charge transfer resistance than the other compositions. The high activity and stability of Ti0.2V0.4Bi0.4-oxide introduce it as an efficient photoelectrocatalyst for pollutant degradation by the advanced oxidation process (AOP).