Yinxing Shang

Macroscopic porous MnO2 aerogels for supercapacitor electrodes

A supercapacitor electrode has been fabricated from macroscopic porous MnO2 aerogels, and has demonstrated an enhanced specific capacitance, a high rate capability and excellent cycling durability. The improvement of supercapacitive performance can be attributed to the macro interconnected channels in the aerogel structure, which can not only facilitate mass transfer and reduce dead volume, but also provide an additional benefit of relieving stress.

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.

MnO2 aerogels for highly efficient oxidative degradation of Rhodamine B

High-efficiency oxidative degradation of Rhodamine B (RhB) is demonstrated with manganese dioxide (MnO2) aerogels. The MnO2 aerogels are fabricated by an ice-templating approach from MnO2 nanosheet colloids, which have been synthesized by redox reaction between MnCl2 and KMnO4 in sodium dodecyl sulfate (SDS) aqueous solution. The obtained self-standing MnO2 aerogels show a three dimensional (3D) structure of a percolating network with open pores ranging from hundreds of nanometers to tens of micrometers. The oxidative degradation efficiency of MnO2 aerogels is compared with ultrathin MnO2 nanosheets and commercial MnO2 powder, and the effects of concentration of MnO2 aerogels as well as pH on the degradation efficiency are also investigated. Typically, the MnO2 aerogels show an excellent oxidative degradation performance of RhB (97.6% removed within 10 min) in acidic solution (pH 2.5), which can be attributed to the large open pores and high surface areas of the aerogels. Furthermore, the MnO2 aerogels also exhibit good capability in the degradation of methylene blue (MB) under acidic conditions. It is believed that MnO2 aerogels hold great promise for future applications in organic pollutant removal with virtues of high efficiency, low cost and environmental friendliness.

ZnO nanodisks decorated with Au nanorods for enhanced photocurrent generation and photocatalytic activity

A facile approach for the preparation of Au nanorod/ZnO nanodisks (AuNR/ZnONDKs) through in situ nucleation and growth of ZnO in AuNR colloidal solution was developed. This is the first report of AuNRs modified on the ZnO surface. Furthermore, the aspect ratios of AuNRs in nanohybrids of AuNR/ZnONDKs were also tuned to achieve tunable and broad LSPR bands for an optimized photocatalytic performance. All of the resultant AuNR/ZnONDK nanohybrids with exposed AuNRs exhibit much higher photocatalytic activity and photocurrent generation compared to commercial ZnO (C-ZnO). In particular, AuNR-707/ZnONDKs express a swift and steady photocurrent of 0.33 mA cm−2, which is 16.5 times higher than the photocurrent generated by C-ZnO. The facile approach presented here opens up a new avenue for the rational design and preparation of high-performance photocatalysts for the future applications in both environmental purification and photoelectric conversion.

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).

Spiky nanohybrids of TiO2/Au nanorods for enhanced hydrogen evolution and photocurrent generation

The fabrication of photocatalysts to achieve efficient utilization of renewable solar energy has attracted broad interest. Herein, a plasmonic spiky TiO2/Au nanorod (NR) nanohybrid was prepared by in situ nucleation and growth of spiky TiO2 in AuNR colloidal solution. The spiky TiO2/AuNR nanohybrids demonstrated enhanced hydrogen evolution activity and photocurrent generation under both visible light and simulated solar light irradiation as compared to bare spiky TiO2 nanoparticles and commercial TiO2. Specifically, the spiky nanohybrids displayed a high H2 production rate of 1.81 mmol g−1 h−1 under simulated solar light irradiation, which is 1.7 times higher than that of TiO2/Au nanosphere nanohybrids, and remain stable for three cycles. The improved photocatalytic H2 evolution demonstrated by the nanohybrids can be ascribed to the coupling effect of the AuNRs and the unique spiky structure. Furthermore, the charge transfer process during H2 evolution was investigated by photocurrent and electrochemical impendence spectroscopy (EIS) measurements. A fast and stable photocurrent was observed for the spiky TiO2/AuNR nanohybrid photoelectrode under both visible light and simulated solar light irradiation, while the EIS plots indicate a rapid charge transfer within the nanohybrids. Such a nanohybrid with a bio-inspired structure will afford new insights for the fabrication of novel photocatalysts.