A self-stabilized Z-scheme porous g-CN/I-containing BiOI ultrathin nanosheets (g-CN/I-BiOI) heterojunction photocatalyst with I/I redox mediator was successfully synthesized by a facile solvothermal method coupling with light illumination. The structure and optical properties of g-CN/I-BiOI composites were systematically characterized by means of X-ray diffraction, scanning electron microscopy, transmission electron microscopy, Fourier transform infrared, X-ray photoelectron spectroscopy, N adsorption/desorption, UV-vis diffuse reflectance spectrum, and photoluminescence. The g-CN/I-BiOI composites, with a heterojunction between porous g-CN and BiOI ultrathin nanosheets, were first applied for the photocatalytic elimination of ppm-leveled CHSH under light-emitting diode visible light illumination. The g-CN/I-BiOI heterojunction with 10% g-CN showed a dramatically enhanced photocatalytic activity in the removal of CHSH compared with pure BiOI and g-CN due to its effective interfacial charge transfer and separation. The adsorption and photocatalytic oxidation of CHSH over g-CN/I-BiOI were deeply explored by in situ diffuse reflectance infrared Fourier transform spectroscopy, and the intermediates and conversion pathways were elucidated and compared. Furthermore, on the basis of reactive species trapping, electron spin resonance and Mott-Schottky experiments, it was revealed that the responsible reactive species for catalytic CHSH composition were h, O, and O; thus, the g-CN/I-BiOI heterojunction followed an indirect all-solid state Z-scheme charge-transfer mode with self-stabilized I/I pairs as redox mediator, which could accelerate the separation of photogenerated charge and enhance the redox reaction power of charged carriers simultaneously.

No abstract

No abstract

A facile, cost-effective approach to obtain sensor electrode materials with excellent electrochemical performance for sensitive and fast detection of 4-nitrophenol (4-NP) is of great importance to the environment and human health. Herein, a smart strategy was proposed for fabrication of nitrogen-doped hierarchical porous carbon (NPC) material with large surface area and unique hierarchical porous structure derived from conveniently available carbohydrates via a facile process. NPC combined with chitosan (CTS) was used to modify an indium-tin oxide (ITO) electrode, referred to as a CTS/​NPC/​ITO electrode, in which CTS acted as dispersant and immobilization reagent. On the basis of the optimum conditions, 4-NP was successfully deposited on a CTS/​NPC/​ITO electrode and the cathodic deposit of 4-NP showed reversible characteristics in a potential range between −0.22 and −0.00 V as well as high ionic-electronic conductivity. Moreover, the electrochemical reaction kinetics and mechanism of 4-NP were explored in detail by CVs, FTIR spectra, and LC–MS. The response sensitivities of the electrode for 4-NP were obtained as 4.85 μA μM–1, 2.212 μC μM–1, and 0.118 μA μM–1 (RSD ∼ 5%) while detection limits (S/N = 3) were 27.55, 30.10, and 5.44 μM by applying cyclic voltammetry, chronocoulometry, and differential pulse voltammetry, respectively. The results were presented to demonstrate that the CTS/​NPC/​ITO electrode had excellent reproducibility, repeatability, good stability, and high selectivity for detecting 4-NP in real water samples.

No abstract