One-step hydrothermal synthesis of C-N-S-tridoped TiO2-based nanosheets photoelectrode for enhanced photoelectrocatalytic performance and mechanism

C-N-S-tridoped TiO2-based nanosheets(BNSs) photoelectrode was prepared via a one-step hydrothermal strategy of the Ti plate in mixed solution of NaOH and cystine, followed by acid-washing and calcination. The resulting samples were characterized by X-ray photoelectron spectroscopy (XPS), scanning electrons microscopy (SEM), X-ray diffraction (XRD) and UV-vis diffuse reflectance spectra (DRS). XPS analysis indicated that C, N and S were transferred into the lattice of TiO2. Highly ordered TiO2-BNSs with the sheet lengths of 500–1500 nm and thickness of about 30 nm were observed. XRD patterns showed that TiO2-BNSs before and after C, N and S tridoping were biphase of anatase-rutile. And tridoping with C, N and S could promote the phase transition from anatase to rutile and restrain growth of rutile crystallites. In addition, a shift of the absorption edge towards low energy and the intense visible light absorption were achieved. Photoelectrochemical (PECH) properties of the C-N-S-tridoped TiO2-BNSs photoanode were investigated through transient photocurrent response (TPR), open-circuit potential (OCP) and electrochemical impedance spectroscopy (EIS). The photoelectrocatalytic(PEC) performances were evaluated by the yield of
• OH radicals and degradation of methyl orange(MO) under Xenon lamp irradiation. The results showed that C-N-S-tridoped TiO2-BNSs photoelectrode revealed high photogenerated current of 0.69 mAcm−2, open-circuit photovoltage of -0.66 mVcm−2, generation of
• OH radicals and PEC efficiency of 96.8% for the degrading MO. Moreover, the enhanced PEC mechanism was proposed. The high PEC performance could be ascribed to the tridoping with C, N and S, which could not only improve the light harvesting in visible region but also enhance the mobility and separation efficiency of photogenerated charge carriers.

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