Enhancement of visible-light-driven photoresponse of Mn/ZnO system: photogenerated charge transfer properties and photocatalytic activity.

A visible-light-active ZnO photocatalyst system in the presence of manganese ions (Mn/ZnO) was prepared via a simple and rapid approach. XRD, XPS, Raman scattering and UV-Vis DRS confirmed the manganese exists in multivalent forms (Mn(3+)/Mn(2+)) in the ZnO lattice, furthermore, ZnO light absorption is extended to the visible region. The photocatalytic activities of the catalysts were evaluated by measuring the photodegrading efficiency of 2,4-dichlorophenol (DCP) under visible light irradiation. With an optimal molar ratio of 5% in Mn/ZnO the highest rate photodegradation was achieved under the experimental conditions. We have characterized the separation and transfer behavior of the photogenerated charges in the visible region by means of surface photovoltage (SPV), surface photocurrent (SPC) and transient photovoltage (TPV) techniques. Based on the comprehensive investigation of the photovoltaic properties of Mn/ZnO photocatalyst, we illustrate the behavior of photogenerated charges have distinct effects on the photocatalytic activity. It is demonstrated that the incorporation of multivalent Mn in ZnO promoted the separation of photogenerated charges, inhibited the recombination of photogenerated carriers, and thus prolonged the charges lifetime to participate in the photocatalytic reaction, resulting in highly efficient photocatalytic activity, which is attributed to the formation of a strong electronic interaction between the multivalent Mn and ZnO.

Fabrication of single gold particle arrays with pattern directed electrochemical deposition.

A simple and efficient method for fabricating gold nanoparticle (AuNP) arrays is developed. With this method, the AuNP arrays are fabricated by taking an electrochemical deposition (ECD) process on the ITO substrate, which is initially patterned with nanoimprint lithography (NIL). The stamp for NIL is fabricated by the cost-efficient nanosphere lithography (NSL). The size of the AuNPs can be adjusted by varying the potential and duration of ECD. In this work, the diameters of AuNPs are varied from 130 to 420 nm. The AuNP arrays can be readily extended to other conductive substrates, which may be applied for detecting and sensing.

On-plate selective enrichment and self-desalting of peptides/proteins for direct MALDI MS analysis.

In this paper, a new technique has been proposed to achieve simultaneous peptides/proteins enrichment and wash-free self-desalting on a novel sample support with a circle hydrophobic-hydrophilic-hydrophobic pattern. Upon deposition, the sample solution is first concentrated in a small area by repulsion of the hydrophobic outer layer, and then, the peptides/proteins and coexisting salt contaminants are selectively captured in different regions of the pattern through strong hydrophobic and hydrophilic attractions, respectively. As a result, the detection sensitivity is improved by 2 orders of magnitude better than the use of the traditional MALDI plate, and high-quality mass spectra are obtained even in the presence of NaCl (1 M), NH(4)HCO(3) (100 mM), or urea (1 M). The practical application of this method is further demonstrated by the successful analysis of myoglobin digests with high sequence coverage, demonstrating the great potential in proteomic research.

Fabrication of hierarchical structures by unconventional two-step imprinting.

We present a simple sequential imprinting lithography method to fabricate micro/nanoscale hierarchical structures. This method involves hot embossing and capillary force lithography with two stamps of different microscales, which avoids using nanoscale stamps. By varying the experimental conditions in the capillary force lithography process, the morphology of the resulting structures can be controlled. This method may provide a facile and low-cost route for fabricating large area patterns of hierarchical structures.

Fabrication of periodic metal nanowires with microscale mold by nanoimprint lithography.

In this paper, a simple method is demonstrated for fabricating periodic metal nanowires based on the unconventional nanoimprint lithography (NIL) technique. Using this method, sub-100 nm metal nanowires with the rectangular cross-section are fabricated with microscale stamp. Furthermore, the metal nanowires with different widths and heights can be generated by adjusting the imprinting parameters with the same stamp. The metal nanowires prepared with this method can be used for chemical sensing, such as ammonia sensing, and it may have applications in optical signal processing.

Fabrication of superhydrophobic polymer films with hierarchical silver microbowl array structures.

Flexible superhydrophobic polyvinyl alcohol (PVA) films with silver bowl-like array structure are fabricated based on the thermal evaporation with sphere monolayer as templates and the modification of 1H, 1H, 2H, 2H-perfluorodecanethiol on silver surface. The silver microbowl arrays were composed of silver nanoparticles with an average diameter size of ca. 10 nm. The polymer films exhibit excellent stability and remarkable superhydrophobicity with a high water contact angle (CA) of about 163° and a low sliding angle (SA) of less than 3°.

Color tuning via adjusting the dye-loading capacity of a polymer.

Color tuning from monomer emission to aggregate emission was accomplished by vacuum thermal evaporation of N,N'-di(n-butyl)quinacridone onto UV-cured photopolymer (NOA-63) with different exposure time. The diffusion of dye molecules into the polymer matrix can be controlled by varying the curing time, which induces the change in the mole ratio between the monomers that are molecularly dispersed into polymer and the aggregates that are shielded on the polymer surface. On the basis of this principle, dual-color and multicolor luminescence patterning were demonstrated by depositing dye molecules onto photolithographically patterned NOA-63 with binary masks and grayscale masks, respectively.