Photocatalytic reduction of triclosan on Au-Cu2O nanowire arrays as plasmonic photocatalysts under visible light irradiation

Seeded Growth of Au@CuxO Core-Shell Mesoporous Nanospheres and Their Photocatalytic Properties

We report a facile synthesis of Au@CuxO core-shell mesoporous nanospheres with tunable size in the aqueous phase via seeded growth. The success of the current work relies on the use of a halide-free copper (Cu) precursor and n-oleyl-1,3-propanediamine as a capping agent to facilitate the formation of a copperish oxide shell with a mesoporous structure and the presence of mixed oxidation states of Cu. By varying the amount of spherical Au seeds while keeping other parameters unchanged, their diameters could be readily tuned without noticeable change in morphology. As compared with commercial Cu2O, the as-prepared Au@CuxO core-shell mesoporous nanospheres exhibit the higher adsorption ability, enhanced activity, and excellent stability toward photocatalytic degradation of methyl orange (MO) under visible light irradiation, indicating their potential applications in water treatment.

Recent Advances in the Design and Photocatalytic Enhanced Performance of Gold Plasmonic Nanostructures Decorated with Non-Titania Based Semiconductor Hetero-Nanoarchitectures

Plasmonic photocatalysts combining metallic nanoparticles and semiconductors have been aimed as versatile alternatives to drive light-assisted catalytic chemical reactions beyond the ultraviolet (UV) regions, and overcome one of the major drawbacks of the most exploited photocatalysts (TiO2 or ZnO). The strong size and morphology dependence of metallic nanostructures to tune their visible to near-infrared (vis-NIR) light harvesting capabilities has been combined with the design of a wide variety of architectures for the semiconductor supports to promote the selective activity of specific crystallographic facets. The search for efficient heterojunctions has been subjected to numerous studies, especially those involving gold nanostructures and titania semiconductors. In the present review, we paid special attention to the most recent advances in the design of gold-semiconductor hetero-nanostructures including emerging metal oxides such as cerium oxide or copper oxide (CeO2 or Cu2O) or metal chalcogenides such as copper sulfide or cadmium sulfides (CuS or CdS). These alternative hybrid materials were thoroughly built in past years to target research fields of strong impact, such as solar energy conversion, water splitting, environmental chemistry, or nanomedicine. Herein, we evaluate the influence of tuning the morphologies of the plasmonic gold nanostructures or the semiconductor interacting structures, and how these variations in geometry, either individual or combined, have a significant influence on the final photocatalytic performance.

Triclosan Removal in Microbial Fuel Cell: The Contribution of Adsorption and Bioelectricity Generation

The occurrence of Triclosan (TCS) in natural aquatic systems has been drawing increasing attention due to its endocrine-disruption effects as well as for the development of antibiotic resistances. Wastewater discharge is the main source of water contamination by TCS. In this study, the removal of TCS in microbial fuel cells (MFCs) was carefully investigated. A 94% removal of TCS was observed with 60 mV electricity generation as well as a slight drop in pH. In addition, we found that adsorption also contributed to the removal of TCS in aqueous solution and 21.73% and 19.92% of the total mass was adsorbed to the inner wall of the reactor and to the electrode, respectively. The results revealed that the attenuation of TCS depends on both biodegradation and physical adsorption in the anode chamber. Thus, the outcomes of our study provide a better understanding of the TCS removal mechanism in MFCs.

Experimental Design and Optimization of Triclosan and 2.8-Diclorodibenzeno-p-dioxina Degradation by the Fe/Nb2O5/UV System

This study describes the experimental design and optimization of the photocatalytic reaction using the immobilized catalyst Fe/Nb2O5 in the degradation of Triclosan and 2.8-DCDD. The techniques employed to characterize the photocatalysts were: specific surface area, average pore volume, average pore diameter, photo-acoustic spectroscopy (PAS), X-ray diffraction (XRD), and scanning electron microscopy (SEM/EDS). The reaction parameters studied were pH, catalyst concentration, catalyst calcination temperature, and nominal metallic charge. The results indicated that the immobilized Fe/Nb2O5 catalysts were efficient in the degradation of Triclosan and 2.8-dichlorodibenzene-p-dioxin. The catalysts with nominal metal loading of 1.5% Fe calcined at 873 K showed the highest constant reaction rate and the lowest half-life 0.069 min−1 and 10.04 min. Tests in different matrices indicated that the photocatalytic reaction using aqueous solution containing Cl− is faster when compared with the ultrapure water matrix.

Folded-up thin carbon nanosheets grown on Cu2O cubes for improving photocatalytic activity

Fabrication of carbon films on semiconductor micro/nanocrystals improves their photocatalytic performance. However, the carbon coating can often lead to reduction in their activity because of the blocking of the reaction sites. Herein, we report the synthesis of folded-up thin carbon nanosheets on Cu₂O cubes by surface etching, which increase the photocatalytic activity of Au/Cu₂O 2 fold due to the enhancement in light absorption and charge separation.

Development of Plasmonic Cu2O/Cu Composite Arrays as Visible- and Near-Infrared-Light-Driven Plasmonic Photocatalysts

We describe efficient visible- and near-infrared (vis/NIR) light-driven photocatalytic properties of hybrids of Cu₂O and plasmonic Cu arrays. The Cu₂O/Cu arrays were prepared simply by allowing a Cu half-shell array to stand in an oxygen atmosphere for 3 h, which was prepared by depositing Cu on two-dimensional colloidal crystals with a diameter of 543 or 224 nm. The localized surface plasmon resonances (LSPRs) of the arrays were strongly excited at 866 and 626 nm, respectively, at which the imaginary part of the dielectric function of Cu is small. The rate of photodegradation of methyl orange was 27 and 84 times faster, respectively, than that with a Cu₂O/nonplasmonic Cu plate. The photocatalytic activity was demonstrated to be dominated by Cu LSPR excitation. These results showed that the inexpensive Cu₂O/Cu arrays can be excellent vis/NIR-light-driven photocatalysts based on the efficient excitation of Cu LSPR.

A novel p–n heterostructured photocatalyst for the efficient photocatalytic degradation of different kinds of organic compounds under irradiation of both ultraviolet and visible light

In this study, BiOBr–titanium phosphate (BiOBr/TP) plate-on-plate composites with p–n heterojunctions were synthesized using a simple, feasible two-step method.