Investigation of the Kinetics of a TiO₂ Photoelectrocatalytic Reaction Involving Charge Transfer and Recombination through Surface States by Electrochemical Impedance Spectroscopy

Abstract

In this paper, the electrochemical impedance spectroscopy (EIS) mathematical model of TiO2 photoelectrocatalytic (PEC) reactions involving charge transfer and recombination through surface states was developed. The model was used to study the kinetics of photoelectrocatalytic decomposition of salicylic acid. The model simulation results show that the appearance of two distinguishable semicircles in the EIS response depends on the charging of surface state and light intensity. The experimental results demonstrated that similar phenomena to the theoretical simulation results. The model provides a way to obtain the rate constants for the photoelectrochemical reactions of surface states mediating charge transfer and recombination. The applied potential changes not only the recombination rate constant but also the charge-transfer rate constant. Moreover, the experimental EIS results here and those previous published on PEC degradation reactions can be explained by the present model satisfactorily. The relevance of surface states was discussed briefly. The results demonstrated that EIS is a powerful tool for studying the kinetics of PEC decomposition of organic pollutants on TiO2 electrodes.

Photoelectrochemical degradation of anti-inflammatory pharmaceuticals at Bi2MoO6–boron-doped diamond hybrid electrode under visible light irradiation

“…Under visible light irradiation of the hybrid electrode, the size of the arc radius on the EIS Nynquist plot is largely reduced due to the photoirradiation. It is believed that the photogenerated charge carriers are efficiently utilized in this hybrid system, which furthermore confirmed the role of Bi 2 MoO 6 photocatalyst in the hybrid electrode [28].…”

Electro-photocatalytic degradation of acid orange II using a novel TiO2/ACF photoanode

“…Photoirradiation and the application of 0.5 V of bias potential increased the curvature of the arc further compared with that of the photoirradiation-only condition. This means that effective separation of the photogenerated electronhole pairs and fast interfacial charge transfer to the electron donor/electron acceptor took place as suggested by Leng et al (2005). Thus, electro-photocatalytic process can degrade AOII effectively.…”

“…Electrochemical impedance spectroscopy (EIS) is a powerful tool to study the electro-photocatalytic activity on TiO 2 electrode (Leng et al, 2005). EIS measurements were carried out covering the frequency range of 0.1 Hz and 100 kHz using a potential of 10 mV.…”

“…It is clear that the curvature of the arc of the EIS Nyquist plot increased (or radius reduced) due to photoirradiation. Liu et al (2000) and Leng et al (2005) suggested that the curvature of the arc of the EIS Nyquist plot was a reflection of the reaction rate at the electrode surface. The results confirmed that photoirradiation enhanced the degradation rate of AOII.…”

Nanoarchitectonics of a Au nanoprism array on WO3film for synergistic optoelectronic response

“…Figure 5(c) shows the EIS response of the WO 3 films to the illumination with λ > 400 nm at a bias voltage of 0.1 V versus the SCE reference electrode. In the EIS spectra, the size of the arc radius on the EIS Nyquist plot correlates with the reaction rate at the surface of the photoanode [50,51]. The arc radius for the WO 3 -Au-nanoprisms film is smaller than that for the bare WO 3 film, indicating that the photogenerated electrons and holes were effectively separated and the interfacial carrier transfer was increased.…”