Spiky nanohybrids of titanium dioxide/gold nanoparticles for enhanced photocatalytic degradation and anti-bacterial property.

We present a facile two-step procedure for synthesizing spiky nanohybrids of titanium dioxide/gold (TiO2/Au) nanoparticles. In this process, spiky TiO2 is obtained using a hydrothermal method, followed by the introduction of plasmonic Au nanoparticles (AuNPs) via a photoreduction approach in which titanium fluoride and chloroauric acid tetrahydrate are used as raw materials. The photodegradation property of the resulting sample was evaluated according to the removal of Rhodamine B (RhB) and ciprofloxacin (CIP) via excitation with visible light. Additionally, the antimicrobial property of the spiky TiO2/Au nanoparticles was examined with respect to the suppression of the growth of Escherichia coli (E. coli). Compared with commercial TiO2, the spiky TiO2/Au nanoparticles exhibited a significantly enhanced photocatalytic efficiency in persistent organic pollutant degradation and bacteria inactivation under simulated environmental conditions. The photocatalysis mechanism primarily entails the combination of AuNPs with spiky TiO2 nanoparticles, which increases the optical path owing to the unique spiky structures of the latter. This results in an improved light-harvesting efficiency based on the localized surface plasmon resonance (LSPR) of AuNPs and the promotion of the charge-separation efficiency through electron-trap processes. These nanoparticles realize the objective of effectively addressing the inherent weaknesses of bare TiO2 and potentially facilitate new fitting approaches for applications in sewage treatment and marine antifouling paint.

Ag@Fe3O4 Core-Shell Surface-Enhanced Raman Scattering Probe for Trace Arsenate Detection.

Developing an effective and reliable method for trace arsenic (As) detection is a prerequisite for improving the safety of drinking water. In this paper, we designed and prepared Ag@Fe3O4 core-shell nanoparticles (NPs), which were then used as Surface-Enhanced Raman Scattering (SERS) probe for trace arsenate (As(V)) detection. The Ag@Fe3O4 core-shell NPs were prepared by in situ growth of Fe3O4 NPs on the surface of AgNPs, which can effectively combine the strong adsorption ability of Fe3O4 nanoshells to As(V) with high SERS activity of Ag nanocores to decrease the detection limit. By use of Ag@Fe3O4 core-shell NPs for As(V) detection, the detection limit can be as low as 10 µg/L, and a good linear relationship between the SERS intensity of As(V) and their concentrations in the range from 10 to 500 µg/L was achieved. Furthermore, Ag@Fe3O4 core-shell NPs could be regenerated through desorption of As(V) from Fe3O4 nanoshells in NaOH solution, and then used for recyclic SERS detection. Therefore, it has been demonstrated for the first time that multifunctional Ag@Fe3O4 core-shell SERS probe could be applied to realize the highly sensitive and reversible detection of As(V).

Bioinspired self-standing macroporous Au/ZnO sponges for enhanced photocatalysis.

A self-standing macroporous noble metal-zinc oxide (ZnO) sponge of robust 3D network has been fabricated through in-situ growth method. The key to the construction of the bioinspired sponge lies in the choice of commercial polyurethane sponge (CPS) with interconnected and junction-free macroporous structure as the skeleton to support Au/ZnO nanorods (Au/ZnONRs). The resultant Au/ZnO/CPS not only exhibits hierarchical structures representing physical features of CPS, but also demonstrates durable superior photocatalytic activity and hydrogen generation capability. In addition, we have adopted various irradiations to investigate the effect of UV light and visible light on the photocatalytic performance of Au/ZnO/CPS individually. In detail, the photocatalytic properties of Au/ZnO/CPS and ZnO/CPS have been monitored and compared under irradiations of different wavelengths (200-1100, 350-780, 200-420 and 420-780 nm) for 90 min to reveal the effect of irradiation wavelength on the activity of photocatalysts. A possible mechanism between irradiation wavelength and photocatalytic degradation efficiency is proposed. The facile in-situ growth approach presented herein can be easily scaled up, affording a convenient method for the preparation of self-standing 3D macroporous materials, which holds great potential for the application in both environmental purification and solar-to-hydrogen energy conversion.