Ming Zhuo

Hierarchical Mo-decorated Co3O4 nanowire arrays on Ni foam substrates for advanced electrochemical capacitors

Herein, we report the synthesis of hierarchical small quantity Mo-decorated Co3O4 nanowire arrays on nickel foam substrates by a powerful two-step solution-based method. The “oriented attachment” and “self-assembly” crystal growth mechanisms are proposed to discuss the growth of the Mo-decorated Co3O4 heterostructures. This heterostructure material with a high specific surface areas provides an extraordinarily high area capacitance of 3.5 F cm−2 at a current density of 17 mA cm−2 (∼2000 F g−1 at a current density of 10 A g−1) in the initial cycles, compared with a bare Co3O4 nanowire array electrode with 2.2 F cm−2 at 17 mA cm−2 (∼1257 F g−1 at 10 A g−1), exhibiting a significant increase in the capacitance of around 60%. When the current density of the hybrid array is increased by 20 times (1.7 to 34 mA cm−2), more than 73% of the specific capacitance can be maintained, which shows a good rate performance. Such a growth approach offers a versatile technique for the design and synthesis of metal oxide hierarchical nanoarrays for electrochemical energy storage applications.

Indium-tin-oxide thin film transistor biosensors for label-free detection of avian influenza virus H5N1.

As continuous outbreak of avian influenza (AI) has become a threat to human health, economic development and social stability, it is urgently necessary to detect the highly pathogenic avian influenza H5N1 virus quickly. In this study, we fabricated indium-tin-oxide thin-film transistors (ITO TFTs) on a glass substrate for the detecting of AI H5N1. The ITO TFT is fabricated by a one-shadow-mask process in which a channel layer can be simultaneously self-assembled between ITO source/drain electrodes during magnetron sputtering deposition. Monoclonal anti-H5N1 antibodies specific for AI H5N1 virus were covalently immobilized on the ITO channel by (3-glycidoxypropyl)trimethoxysilane. The introduction of target AI H5N1 virus affected the electronic properties of the ITO TFT, which caused a change in the resultant threshold voltage (VT) and field-effect mobility. The changes of ID-VG curves were consistent with an n-type field effect transistor behavior affected by nearby negatively charged AI H5N1 viruses. The transistor based sensor demonstrated high selectivity and stability for AI H5N1 virus sensing. The sensor showed linear response to AI H5N1 in the concentrations range from 5×10(-9) g mL(-1) to 5×10(-6) g mL(-1) with a detection limit of 0.8×10(-10) g mL(-1). Moreover, the ITO TFT biosensors can be repeatedly used through the washing processes. With its excellent electric properties and the potential for mass commercial production, ITO TFTs can be promising candidates for the development of label-free biosensors.

Facile construction of graphene-like Ni3S2 nanosheets through the hydrothermally assisted sulfurization of nickel foam and their application as self-supported electrodes for supercapacitors

A facile and low-cost approach has been developed for the fabrication of large-area nickel sulfide nanosheets via the hydrothermally assisted sulfurization of Ni foam. The obtained Ni3S2 nanosheets exhibit perfect supercapacitor performance, retaining almost 93.6% of the maximum capacitance after 3000 cycles. The strategy of self-sulfurization is promising for use in the construction of other nanoarchitectured sulfide (e.g., CuS, FeS and SnS) arrays for electrochemical applications.

NiMoO4@Co(OH)2 core/shell structure nanowire arrays supported on Ni foam for high-performance supercapacitors

NiMoO4@Co(OH)2 core/shell structure nanowire arrays (NWAs) supported on Ni foam were successfully fabricated via a facile hydrothermal growth and electrochemical deposition route, and applied in supercapacitors (SCs). The smart combination of Co(OH)2 and NiMoO4 nanostructures in nanowire arrays exhibited greatly enhanced electrochemical performance. Co(OH)2 nanoflakes were uniformly wrapped on the surface of each NiMoO4 nanowire, which increased the capacitance of NiMoO4 NWAs to a high areal capacitance of 2.335 F cm−2 at 5 mA cm−2 and 0.909 F cm−2 at 50 mA cm−2. The electrode also exhibited good cycling ability; 83% of the initial capacity was retained after 5000 cycles at a current density of 20 mA cm−2. These results indicate that the NiMoO4@Co(OH)2 NWAs could be a promising electrode material for high-performance electrochemical capacitors.

Highly sensitive humidity sensors based on Sb-doped ZnSnO3 nanoparticles with very small sizes

Highly sensitive and fast responding humidity sensors were fabricated based on Sb-doped ZnSnO3 fine nanoparticles, which were synthesized via a dual-hydrolysis-assisted liquid precipitation reaction and subsequent hydrothermal procedure. The nanoparticles were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and UV-visible spectrophotometry. The results demonstrated that ZnSnO3 nanocubes evolved into Sb-doped ZnSnO3 nanoparticles with doping by Sb. This evolution facilitated their application in humidity sensing. At room temperature, the resistance of the humidity sensors based on Sb-doped ZnSnO3 at 30% relative humidity (RH) was 130 times greater than that in air with 85% RH. The response and recovery times were 7.5 s and 33.6 s, respectively, when the sensors were switched between 30% and 85% RH. These results are much better than those reported so far. The present results may present new opportunities for the practical application of high-performance humidity sensors at room temperature.

Humidity sensors based on graphene/SnOx/CF nanocomposites

In this study, we investigated the nanocomposites composed of graphene, SnOx and carbon fibers (CFs) for humidity sensing applications. The composites were obtained by an electrospinning method followed by addition of graphene. SnOx/CFs uniformly dispersed into graphene nanosheets. SnOx and graphene were proved to be promising sensing materials. The amorphous carbon fibers could supply more channels for transportation of protons or electrons. Therefore, the composites exhibited high humidity sensing performance. The resistance of the sensor increases two times with decreasing relative humidity from 55% to 30%. The sensitivity to humidity increased by almost 100% after adding graphene to SnOx/CF nanocomposites. The response and recovery times were 8 s and 6 s at 30% RH, respectively. The results demonstrated that rational design of nanocomposites with graphene could be a favorable strategy to improve humidity sensing properties.

Ternary doped porous carbon nanofibers with excellent ORR and OER performance for zinc–air batteries

The oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) play an important role in the air electrode reactions of rechargeable Zn–air batteries. However, noble metal-based catalysts for the ORR and OER always suffer from high cost and poor stability. Carbon-based materials with many advantages such as low cost, good conductivity, a large specific surface area and considerable durability are considered as promising alternatives to noble metal-based catalysts. In particular, the doping of heteroatoms into carbon has been proven to be an effective method to improve catalytic performance. Herein, we synthesized N, F, P ternary doped macro-porous carbon fibers (NFPC) as a bifunctional catalyst for primary and rechargeable Zn–air batteries for the first time via an electrospinning method with subsequent thermal annealing. The uniform distribution of heteroatoms in the macroporous carbon fibers induced a greatly improved catalytic efficiency towards the ORR and OER, showing exceptional properties in Zn–air systems.

Diethylamine gas sensor using V2O5-decorated α-Fe2O3 nanorods as a sensing material

V2O5-decorated α-Fe2O3 composite nanorods were synthesized successfully by electrospinning and an environmentally-friendly soak-calcination method. The composite showed high selectivity and stability to diethylamine gas as well as ultra fast response times within 2 s to 100 ppm diethylamine gas.

Mesoporous tin oxide nanospheres for a NO x in air sensor

Mesoporous tin oxide(SnO 2 /with a high surface area of 147.5 m 2 /g has been successfully synthesized via self-assembly process, combining the driven forces of water-evaporation and molecular interactions. Scanning electron microscope, X-ray diffraction, transmission electron micrograph, Fourier transform infrared and BrunauerEmmett-Teller were employed to analyze the morphology and crystal structure of the as-synthesized mesoporous materials. As a gas sensor, mesoporous SnO 2 shows impressive performances towards NOx gas with high selectivity and stability as well as ultra high sensitivity about 94.3 to 10 ppm NO x gas at 300℃. The best response time of the sample S-500 is about 3.4s to 10 ppm NO x at 450℃.

High-performance humidity sensors based on electrospinning ZnFe2O4 nanotubes

In this paper, ZnFe2O4 nanotubes were fabricated by a simple electrospinning method. The scanning electron microscopy images show that the obtained ZnFe2O4 nanotubes had a hollow structure and had a diameter of about 80–100 nm, and wall thickness of 15–20 nm. A humidity sensor based on as-prepared nanotubes was fabricated and exhibited good performance, high sensitivity, fast response and recovery and good stability. When RH switched between 75% and 35%, the resistance changed from 2.63 × 107 Ω to 1.65 × 109 Ω. The corresponding sensitivity was calculated to be 62.7. The response and recovery time was 11 s and 5.6 s respectively. The sensor also showed good stability and repeatability. These results indicated that the synthesized ZnFe2O4 nanotubes were promising candidates for high-performance humidity sensors.