Carbon quantum dots-decorated TiO2/g-C3N4 film electrode as a photoanode with improved photoelectrocatalytic performance for 1, 4-dioxane degradation. (July 2020)

• Record Type: Journal Article
• Authors: Su, Yuehan; Liu, Guangli; Zeng, Cuiping; Lu, Yaobin; Luo, Haiping; Zhang, Renduo
• Is Part Of: Chemosphere. Volume 251(2020)
• Publication Date: 2020-07
• Subjects: Photoelectrocatalysis -- TiO2 nanorods -- Graphite carbon nitride -- Carbon quantum dots -- 1, 4-Dioxane; Pollution -- Periodicals; Pollution -- Physiological effect -- Periodicals; Environmental sciences -- Periodicals; Atmospheric chemistry -- Periodicals; 551.511
• DOI: 10.1016/j.chemosphere.2020.126381
• Languages: English
• ISSNs: 0045-6535

Abstract

Abstract: In this study, carbon quantum dots (CQDs) were used to decorate a TiO2 /g-C3 N4 (TCN) film electrode. The morphological, optical, and electrochemical properties of the TiO2 /g-C3 N4 /CQDs nanorod arrays (TCNC NRAs) film were investigated using transmission electron microscopy (TEM), scanning electron microscopy (SEM), UV–vis diffuse reflectance spectroscopy (DRS), photoluminescence (PL), and electrochemical impedance spectroscopy (EIS). The improved optical properties, photoelectrochemical properties and photoelectrocatalytic (PEC) performance of photoanode can be observed by doping CQDs onto the TCN NRAs film. Compared with TiO2 NRAs and TCN NRAs, the narrower band gap of 2.47 eV and longer lifetime of photoinduced electron-hole pairs were observed in the TCNC NRAs. Under visible light irradiation and a bias voltage of 1.2 V, the photocurrent density and 1, 4-dioxane (1, 4-D) removal rate of PEC process with TCNC NRAs electrode reached 0.16 mA/cm 2 and 77.9%, respectively, which was 2.5 times and 1.5 times of that with TCN NRAs electrode. TCNC NRAs electrode could keep >75% of the 1, 4-D removal rate during five cycles tests. High PEC performance with TCNC NRAs electrode could be attributed to the enhanced charge separation and the change of electron transfer mechanism from typical heterojunction to Z-scheme, which may increase the active species production and change the dominant reactive species from O2 · - to ·OH. Our experimental results should be useful for studying the degradation of 1, 4-D and developing efficient PEC materials. Graphical abstract: Image 1 Highlights: A visible-light-driven TiO2 /g-C3 N4 /CQDs nanorod arrays photoanode was prepared. Improved photocurrent production and 1, 4-dioxane removal were achieved. The doping of CQDs increased the reactive species production. The doping of CQDs changed the dominant reactive species from O2 · - to ·OH. The Z-scheme mechanism was proposed for the TiO2 /g-C3 N4 /CQDs nanorod arrays.