Chemical Engineering Journal, Vol.316, 41-49, 2017
All-solid-state Z-scheme photocatalyst with carbon nanotubes as an electron mediator for hydrogen evolution under simulated solar light
In this contribution, the effectiveness of tailor-made multi-walled carbon nanotubes (MWCNTs) as a solid-state electron mediator for facilitating Z-schematic water splitting is demonstrated. An anisotropic Zn0.5Cd0.5S-MWCNT-TiO2 ternary core-shell nanocomposites fabricated by a facile coating and hydrothermal route renders a much higher photocatalytic activity than the corresponding single-and two component systems, revealing MWCNTs can shuttle photogenerated electrons from PS II (TiO2) to PS I (Zn0.5Cd0.5S). This unique type of vectorial electron transfer between the two photosystems imparts an efficient spatial charge isolation and endows suitable relative band pOsitions with strong redox ability to the Z-scheme system. Consequently, the simulated solar-light-driven (AM 1.5) photocatalytic H-2 evolution rate of the as-prepared Zn0.5Cd0.5S-MWCNT-TiO2 photocatalyst (21.9 smol h(-1)) is ca. 4.5- and 2.8-fold enhancement over pristine Zn(0.5)Cda(5)S and MWCNT-Zn0.5Cd0.5S samples, respectively. The structural and chemical properties of the typical photocatalysts were characterized using X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), high resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), photoluminescence (PL) and ultraviolet-visible diffuse spectroscopy (UV-Vis). Besides, electrochemical characterizations (transient photocurrent, Nyquist and Mott-Schottky measurements) were performed to depict the ascendency of the Z-scheme system. Based on the outcomes of the experiment, a plausible charge transfer mechanism for the Z-schematic Zn0.5Cd0.5S-MWCNT-TiO2 system was postulated. (C) 2017 Elsevier B.V. All rights reserved.