Jiangshan Zhang

Microwave-assisted synthesis of NiS2 nanostructures for supercapacitors and cocatalytic enhancing photocatalytic H2 production

Uniform NiS2 nanocubes are successfully synthesized with a microwave-assisted method. Interestingly, NiS2 nanocubes, nanospheres and nanoparticles are obtained by controlling microwave reaction time. NiS2 nanomaterials are primarily applied to supercapacitors and cocatalytic enhancing photocatalytic H2 production. Different morphologies of NiS2 nanostructures show different electrochemical and cocatalytic enhancing H2 production activities. Benefited novel nanostructures, NiS2 nanocube electrodes show a large specific capacitance (695 F g−1 at 1.25 A g−1) and excellent cycling performance (the retention 93.4% of initial specific capacitance after 3000 cycles). More importantly, NiS2 nanospheres show highly cocatalytic enhancing photocatalytic for H2 evolution, in which the photocatalytic H2 production is up to 3400 μmol during 12 hours under irradiation of visible light (λ>420 nm) with an average H2 production rate of 283 μmol h−1.

Facile synthesis of porous ZnO–NiO composite micropolyhedrons and their application for high power supercapacitor electrode materials

Porous ZnO-NiO composite micropolyhedrons have been successfully synthesized by calcination of mixed oxalate (Zn(0.9)Ni(0.1)(C(2)O(4))(2)·nH(2)O) precursors in air. The oxalate precursor micropolyhedrons were synthesized by a mild chemical precipitation method without any template or surfactant, and found to have a relatively low decomposition temperature. We have successfully explored the application of the resulting porous ZnO-NiO composite micropolyhedrons as electrochemical capacitors. Electrochemical study shows that the obtained ZnO-NiO composites under different conditions have different electrochemical supercapacitor properties in 3.0 or 1.0 M KOH solutions. The porous ZnO-NiO micropolyhedron material (P1) obtained by calcination of the oxalate precursor at 400 °C has a large specific capacitance 649.0 F g(-1) in 3.0 M KOH solution and could maintain 99.1% of this value after 400 cycles at 5.8 A g(-1). Even at a high current density of 58.0 A g(-1), the specific capacitance of P1 is 395.2 F g(-1).

Facile fabrication of NH4CoPO4·H2O nano/microstructures and their primarily application as electrochemical supercapacitor

Various NH(4)CoPO(4)·H(2)O nano/microstructures (oblong plate, microplate, microflower, hierarchical architectures) have been synthesized through a facile chemical precipitation method without surfactants and templates. More importantly, the supercapacitive performances of NH(4)CoPO(4)·H(2)O nano/microstructures were firstly studied using cyclic voltammetry, galvanostatic charge/discharge measurements, and electrochemical impedance spectroscopy methods in 3.0 M KOH solution. These results indicated that NH(4)CoPO(4)·H(2)O hierarchical architectures electrodes exhibit effective supercapacitive characteristics in aqueous KOH electrolyte. The specific capacitance of NH(4)CoPO(4)·H(2)O electrode is up to 369.4 F g(-1) at a current density of 0.625 A g(-1) and the material has a long cycle life which can maintain 99.7% of initial specific capacitance after 400 cycles.

Cu superstructures fabricated using tree leaves and Cu–MnO2 superstructures for high performance supercapacitors

Copper (Cu) superstructures have been originally synthesized by using natural sapless leaves. A novel hybrid nanoarchitecture, Cu–MnO2 composite, is prepared through facile coating of a thin MnO2 nanofilm onto the highly electronically conductive Cu superstructures. Benefiting from their unique structures, as electrode materials of supercapacitors the composite superstructures have a high specific capacity of 1024 F g−1 at 1.5 A g−1 and good capacity retention of around 96% after 2000 electrochemical cycles.

Facile synthesis of porous nickel manganite materials and their morphology effect on electrochemical properties

New porous bipyramid, fusiform and plate structured NiMn2O4 materials have been successfully synthesized by calcining oxalate precursors in the air without using any template or surfactant. More importantly, electrochemical measurements show that morphology affects their electrochemical properties, and the porous plate structured NiMn2O4 showed a large specific capacitance and a long cycle life.

NH4CoPO4·H2O microbundles consisting of one-dimensional layered microrods for high performance supercapacitors

Unique layered NH4CoPO4·H2O microbundles consisting of one-dimensional layered microrods are firstly synthesized by a facile hydrothermal method. As a result of novel layered structures, there are many nanolayered channels for the diffusion of ions and electrolytes. The preliminary supercapacitor investigation indicates that the specific capacitance of layered NH4CoPO4·H2O microbundle electrodes reaches up to 662 F g−1 at a current density of 1.5 A g−1 and remains at 520 F g−1 even at 15.0 A g−1. The cycle test shows excellent cycling performance of layered NH4CoPO4·H2O microbundle electrodes (the retention 92.7% of initial specific capacitance after 3000 cycles).

Porous Mn3[Co(CN)6]2·nH2O nanocubes as a rapid organic dyes adsorption material

Porous Mn3[Co(CN)6]2·nH2O nanocubes were successfully synthesized by a surfactant-assisted (PVP) process through a simple precipitation method at room temperature. X-Ray powder diffraction (XRD) and field emission scanning electron microscopy (FE-SEM) were employed for the morphology and structure characterization. The fine-detailed information about porous structures of the samples has also been studied using the Brunauer–Emmet–Teller (BET) isotherm. Most importantly, the prepared porous structured Mn3[Co(CN)6]2·nH2O showed excellent adsorption capacity and rapid adsorption rate for dyes in aqueous solution, such as methyl violet, neutral red, methyl orange and especially for methylene blue. The effects of contact time, initial concentration and initial pH were also investigated. The maximum adsorption capacity of methylene blue was as high as 489.9 mg g−1 and 96.5% of the dye was removed within initial 5 min of contact time. Due to the simple synthetic method, fast adsorption rate and its high adsorption capacity, the synthesized Mn3[Co(CN)6]2·nH2O porous nanocubes could be used as an effective adsorbent for removing dye pollutants from waste water.

Facile control synthesis of Ag3PO4 and morphologies effects on their photocatalytic properties

We reported that Ag3PO4 exhibits excellent photocatalytic properties for organic dye decomposition under visible-light irradiation. Herein, studies of photocatalytic performance have indicated that nano rhombic dodecahedrons (S1) exhibit much higher activities than micro rhombic dodecahedrons (S3) for the degradation of organic contaminants.

Synthesis of hopcalite nanomaterials and study of their properties

Hopcalites were successfully synthesised by flaming a simple precursor. And further measurements show hopcalite nanorodclusters have effective catalytic activity of CO in low temperature compared to the commercial under the same condition; on the other hand the nanorodclusters show excellent antimicrobial activity. More importantly, we also find that different morphologies of hopcalites have different catalytic, antimicrobial and magnetic activities, which may be explained in such a way that different morphologies have different adsorption and desorption of CO or microbe, and also different structures have distinguished site disorders for magnetic behaviour.