Huijuan Geng

Fast one-step synthesis of N-doped carbon dots by pyrolyzing ethanolamine†

Nitrogen-doped carbon dots (N-CDs) were directly synthesized with high yield by pyrolyzing ethanolamine in air within 7 minutes. The obtained N-CDs possess bright blue excitation- and pH-dependent luminescence. This one-step strategy could enable a viable route towards the commercial synthesis of N-CDs.

Efficient long lifetime room temperature phosphorescence of carbon dots in a potash alum matrix

It was found that upon dispersing the carbon dots (CDs) into a KAl(SO4)2·x(H2O) matrix, the CD composite powders showed a long phosphorescence lifetime of 707 ms and an average lifetime of 655 ms. This strategy would provide a novel route for achieving efficient long lifetime room temperature phosphorescence of CDs.

Hydrothermal synthesis of hexagonal CuSe nanoflakes with excellent sunlight-driven photocatalytic activity

Hexagonal CuSe nanoflakes with a lateral size of 200–800 nm and a thickness of 15–40 nm have been successfully synthesized by a concentrated alkaline hydrothermal method in which CuCl and Se powder were used as raw materials. Experimental results show that the amount of polyvinylpyrrolidone and the NaOH concentration play important roles in the formation of hexagonal CuSe nanoflakes. The photocatalytic activity of the as-synthesized hexagonal CuSe nanoflakes was investigated by the photocatalytic degradation of organic methylene blue (MB) under natural sunlight irradiation. It is found that hexagonal CuSe nanoflakes exhibit excellent photocatalytic activity and repeatability and above 99% MB in wastewater can be degraded after sunlight irradiation for 25 min in the presence of hydrogen peroxide.

Spontaneous intercalation of long-chain alkyl ammonium into edge-selectively oxidized graphite to efficiently produce high-quality graphene

Mass production of high-quality graphene nanosheets (GNs) is essential for practical applications. We report that oxidation of graphite by low concentration KMnO4 at relatively high temperature (60°C) leads to edge-selectively oxidized graphite (EOG) which preserves the high crystalline graphitic structure on its basal planes while the edges are functionalized by oxygen-containing groups. Long-chain tetradecyl-ammonium salt (C14N+) could be spontaneously intercalated into EOG to form intercalated EOG-C14N+ compounds. Gentle and short-time sonication of EOG-C14N+ in toluene can full exfoliate EOG into edge-oxidized graphene nanosheets (EOGNs) with concentration of 0.67 mg/ml, monolayer population up to 90% and lateral size from 1 μm to >100 μm. The EOG and EOGN films show excellent electrical conductance, which is far superior to their graphene oxide (GO) counterparts. Our method provides an efficient way to produce high-quality GNs, and the resultant EOG also can be directly used for production of multifunctional materials and devices.

Controlled one-step synthesis of spiky polycrystalline nickel nanowires with enhanced magnetic properties

Polycrystalline spiky Ni nanowires (Ni NWs) with high yield and high aspect ratio have been synthesized using a controlled one-step hydrothermal method in the presence of an external magnetic field. The morphological investigations reveal the spiky growth of the Ni NWs with thorns of 500 nm to 800 nm in length on the surface. This hierarchical structure growth pattern observed on the surface involved plane orientation growth during the nucleation in the presence of an external magnetic field. The best aspect of this methodology is the control of the morphological and growth orientation by tuning the process parameters such as magnetic field, temperature and concentration of reducing agent. The magnetic measurement shows the highest saturation magnetisation value of 61.3 emu g−1 at room temperature that makes its potential for micro/nano magnetic devices.

Facile synthesis and photoelectric properties of carbon dots with upconversion fluorescence using arc-synthesized carbon by-products†

We have demonstrated an easy chemical oxidation approach toward fluorescent carbon dots (CDs) using arc-synthesized carbon by-products. The as-synthesized CDs possess a strong excitation-independent photoluminescence emission located at ca. 502 nm and strong upconversion fluorescence under long wavelength radiation (from 900 to 550 nm). Importantly, the CD-based device has been investigated and exhibits excellent photoresponse under UV irradiation, highlighting the potential for optoelectronic applications.

One-pot preparation of thin nanoporous copper foils with enhanced light absorption and SERS properties

A facile hydrothermal method has been presented to prepare free-standing nanoporous Cu foils (NPCFs) having a thickness of ~1.4 μm and an area of up to ~10 cm2, which were grown on the inwall of a Teflon-lined autoclave by assembling and reducing CuxO nanoparticle intermediates and then peeling themselves off in the cooling period of the reaction. The pore sizes of NPCFs can be adjusted by varying the reaction time. It is observed that the NPCFs with water absorbed inside their nanopores show excellent flexibility while dried ones exhibit a highly hydrophobic nature. Compared with commercially available Cu foils, the as-synthesized NPCFs show enhanced ability to absorb light over a wide range of wavelengths from 200 to 1000 nm because of their nanoporosity. The highest absorbance and the biggest enhancement can reach 86% at 300 nm and 43% at 575 nm, respectively. The smooth side of NPCFs with a hemisphere-like surface demonstrates outstanding surface-enhanced Raman scattering performance by employing Rhodamine 6G as the probe molecule, which agrees well with the results of finite-difference time-domain simulation.

Development of Inorganic Solar Cells by Nano-technology

Inorganic solar cells, as durable photovoltaic devices for harvesting electric energy from sun light, have received tremendous attention due to the fear of exhausting the earth’s energy resources and damaging the living environment due to greenhouse gases. Some recent developments in nanotechnology have opened up new avenues for more relevant inorganic solar cells produced by new photovoltaic conversion concepts and effective solar energy harvesting nanostructures. In this review, the multiple exciton generation effect solar cells, hot carrier solar cells, one dimensional material constructed asymmetrical schottky barrier arrays, noble nanoparticle induced plasmonic enhancement, and light trapping nanostructured semiconductor solar cells are highlighted.

Advances in Conceptual Electronic Nanodevices based on 0D and 1D Nanomaterials

Nanoelectronic devices are being extensively developed in these years with a large variety of potential applications. In this article, some recent developments in nanoelectronic devices, including their principles, structures and potential applications are reviewed. As nanodevices work in nanometer dimensions, they consume much less power and function much faster than conventional microelectronic devices. Nanoelectronic devices can operate in different principles so that they can be further grouped into field emission devices, molecular devices, quantum devices, etc. Nanodevices can function as sensors, diodes, transistors, photovoltaic and light emitting devices, etc. Recent advances in both theoretical simulation and fabrication technologies expedite the development process from device design to prototype demonstration. Practical applications with a great market value from nanoelectronic devices are expected in near future.

Highly uniform hole spacing micro brushes based on aligned carbon nanotube arrays

Highly uniform hole spacing micro brushes were fabricated based on aligned carbon nanotube (CNT) arrays synthesized by chemical vapor deposition method with the assistance of anodic aluminum oxide (AAO) template. Different micro brushes from CNT arrays were constructed on silicon, glass, and polyimide substrates, respectively. The micro brushes had highly uniform hole spacing originating from the regularly periodic pore structure of AAO template. The CNT arrays, serving as bristles, were firmly grafted on the substrates. The brushes can easily clean particles with scale of micrometer on the surface of silicon wafer and from the narrow spaces between the electrodes in a series of cleaning experiments. The results show the potential application of the CNT micro brushes as a cleaning tool in microelectronics manufacture field.