Bei Jin

Fabrication and characterization of high efficiency and stable Ag3PO4/TiO2 nanowire array heterostructure photoelectrodes for the degradation of methyl orange under visible light irradiation

Ag3PO4/TiO2 nanowire array (ATNWs) heterostructure photoelectrodes were prepared by a sequential chemical bath deposition. The structure and optical properties of the ATNWs were characterized by scanning electron microscopy, high-resolution transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, UV-Vis diffuse reflectance spectroscopy, photoluminescence spectroscopy and electrochemical techniques. The photocatalytic activity of the ATNWs was evaluated by photocatalytic degradation of methyl orange (MO) under visible light irradiation (λ > 400 nm). The results showed that Ag3PO4 nanoparticles were successfully formed on the surface of the TiO2 nanowires (NWs) causing no damage to the ordered structure of the nanowires. The p-type Ag3PO4 nanoparticles deposited on the n-type TiO2 NWs could promote the transfer of photo-generated holes, which inhibited the recombination of electrons and holes effectively, leading to a significant increase in the lifetime of the charge carriers. Moreover, the ATNWs show much higher photocatalytic activity and stability than that of the pure TiO2 NWs for the photocatalytic degradation of MO. The enhanced photocatalytic activity could be attributed to the visible-light photocatalytic activity of Ag3PO4 and the heterostructure between Ag3PO4 and TiO2.

Synthesis and enhanced photocatalytic activity of a BiOI/TiO2 nanobelt array for methyl orange degradation under visible light irradiation

A novel heterojunction by facet coupling of BiOI onto TiO2 nanobelt arrays (NBAs) as a visible light photocatalyst was achieved through a hydrothermal method. The BiOI/TiO2 heterojunction had been investigated by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectra (XPS), UV-Vis diffuse reflectance spectroscopy (DRS), photoluminescence (PL) spectroscopy and electrochemical techniques. The BiOI/TiO2 heterojunction presented a significantly enhanced photocatalytic performance in degrading methyl orange (MO) under visible light irradiation. The obviously reduced electron–hole recombination rates of BiOI/TiO2 were demonstrated from PL spectroscopy measurements and the photoelectrochemical evaluation. The 2-BiOI/TiO2 NBAs sample displays the highest photocatalytic activity toward the degradation of the MO solution under visible-light irradiation, corresponding to an apparent pseudo-first-order rate constant kapp of 0.0973 min−1. It is 5 times more than that of a pure TiO2 nanobelt array photocatalyst.

Dramatic visible light photocatalytic degradation due to the synergetic effects of TiO2 and PDA nanospheres

Dramatic visible light photocatalytic activity was obtained for the degradation of methyl orange using TiO2 photocatalysts modified with polydopamine (PDA) nanospheres. The high photocatalytic activity is due to the synergetic effect between PDA and TiO2, which promote the migration efficiency of photogenerated carriers at the interface of PDA and TiO2.

Facile synthesis of MoS2/B-TiO2 nanosheets with exposed {001} facets and enhanced visible-light-driven photocatalytic H2 production activity

Cocatalysts have been extensively used to accelerate the rate of hydrogen evolution in semiconductor-based photocatalytic systems; however, the influence of interface states between the semiconductor and cocatalyst has rarely been investigated. Herein, we demonstrated a feasible strategy of heterogeneous structure to enhance visible light hydrogen generation of the MoS2/B-TiO2 system. Loading of MoS2 nanosheets on the surface of anatase boron doped TiO2 (B-TiO2) nanosheets with exposed {001} facets considerably increases the interfacial contact. At an optimal ratio of 1.0 wt% MoS2, the MoS2/B-TiO2 hybrid photocatalyst showed the highest H2 evolution rate of 0.50 mmol h−1 g−1, which is almost 6 times higher than that of pure B-TiO2 nanosheets. More importantly, the MoS2/B-TiO2 hybrid photocatalyst exhibited photocatalytic activity much higher than that of Pt/B-TiO2 nanosheets and the simple mechanical mixing of B-TiO2 and MoS2 nanosheets photocatalysts. The decisive factor in improving the photocatalytic H2 production activity is an intimate and large contact interface between the light-harvesting semiconductor and cocatalyst. The effective charge transfers from B-TiO2 to MoS2 was demonstrated by the significant enhancement of the photocurrent responses in MoS2/B-TiO2 hybrid electrodes. This study created new opportunities for designing and constructing highly efficient visible light photocatalysts by surface modification or doping.

Photosensitization of Carbon Nitride Photoelectrodes with CdS: A Novel Architecture with Highly Efficient Photocatalytic Activity

CdS with well-defined crystallinity is anchored on carbon nitride photoelectrodes by a successive chemical bath deposition. And the as-synthesized samples were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, ultraviolet-visible diffuse reflection spectroscopy, X-ray photoelectron spectroscopy, and photoluminescence spectroscopy techniques. The effect of the amount of CdS on the catalytic activity for the degradation of acid Orange II is investigated under visible light irradiation. Results show that the photoelectrodes composed of CdS/CN exhibit much higher catalytic activity than pure CN photoelectrodes. A possible photocatalytic mechanism of the CdS/CN electrodes is proposed under visible light irradiation.