Yahui Ma

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).

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.

Mesoporous uniform ammonium nickel phosphate hydrate nanostructures as high performance electrode materials for supercapacitors

Mesoporous uniform ammonium nickel phosphate hydrate nanostructures are successfully prepared by a one-pot hydrothermal method. As a result of the unique feature of large surface area (418 m2 g−1) and tunable mesostructures, the material exhibits good performance as supercapacitor electrodes, with a specific capacitance of 1072 F g−1 in 3.0 M KOH at a current density of 1.50 A g−1, and show a good cycle life which does not obviously decay after 3000 cycles (the retention 95.0% of initial specific capacitance after 3000 cycles).

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.