Zhiyan Guo

Facile surfactant-assisted synthesis of CTAB-incorporated MoS2 ultrathin nanosheets for efficient hydrogen evolution

Molybdenum disulfide (MoS2) has emerged as a promising electrocatalyst for catalyzing protons to hydrogen via the so-called hydrogen evolution reaction (HER). In order to enhance the HER activity, CTAB (cetyltrimethyl ammonium bromide)-incorporated MoS2 ultrathin nanosheets with high specific surface area and more catalytic active sites have been successfully synthesized via a facile surfactant-assisted hydrothermal approach. Adding CTAB to the hydrothermal process can effectively regulate both structural and electronic benefits by controllable disorder engineering and simultaneous CTAB incorporation in MoS2 catalysts, leading to a higher specific surface area, more catalytic active sites and better electrical conductivity for improving HER activity. The optimized CTAB-incorporated MoS2 ultrathin nanosheets exhibit excellent activity for HER with a small onset potential of 88 mV, a low Tafel slope of 55 mV dec−1, and relatively good stability.

Polypyrrole-assisted synthesis of roselike MoS2/nitrogen-containing carbon/graphene hybrids and their robust lithium storage performances

Roselike MoS2/nitrogen-containing carbon/graphene (MoS2/NC/G) hybrids were successfully synthesized via a facile polypyrrole (PPy)-assisted hydrothermal approach in combination with high-temperature calcination. The obtained MoS2/NC/G hybrids manifest roselike MoS2 composed of nanosheets coupled uniformly on NC/G nanosheets due to the strong interactions between MoS2 and the abundant nitrogen-containing functional groups of NC. When used as anode materials for lithium ion batteries, the MoS2/NC/G hybrids exhibit enhanced electrochemical energy storage performances compared to the bare MoS2 nanosheets, including high specific capacity (1570.6 mA h g−1 at 0.1 A g−1), excellent rate capability (704.8 mA h g−1 at 5 A g−1) and good cycling stability (96.4% capacity retention after 100 cycles at 0.2 A g−1). The enhanced lithium storage properties of the MoS2/NC/G hybrids can be ascribed to the boosted electronic conductivity arising from the novel hybrid nanostructures of MoS2/NC/G.

Controllable Synthesis and Electrochemical Behavior of Micro/Nano Octahedron Ceria

Octahedron ceria crystals were fabricated by one-step hydrothermal synthesis without using any hard-template, with Ce(NO3)3·6H2O being raw materials and polyvinylpyrrolidone (PVP) being surfactant. The content of ethanol plays an important role in the morphology evolution of as-obtained CeO2. At 200°C, with the addition of ethanol into the water and by adjusting the ratio between ethanol and water from 1:3 to 3:1, the morphology of the as-obtained CeO2 changed from solid octahedron to hollow irregular particles. When the ratio between ethanol and water is 1:1, prolonging the reaction time from initial 6 h to 12 h and ultimate 48 h, the morphology of the as-obtained CeO2 growing from solid quasi-octahedron to regular octahedron, and then to hollow irregular particles. The electrochemical behavior of carbon paste electrode (CPE) modified by graphene/CeO2/CHIT nanocomposite membrane in 2.0 × 10–5 mol/L methylene blue (MB) containing 0.02 mol/L NaCl, and glassy carbon electrode (GCE) modified by MWNTs/CeO2/CHIT nanocomposite membrane in 1.0 mmol/L K3Fe(CN)6/K4Fe(CN)6 (1:1) containing 0.5 mol/L KCl as the supporting electrolyte were measured respectively. The electrochemical measurements were carried out by cyclic voltammetric (CV) and differential pulse voltammetry (DPV). The synergistic effects of as-synthesized micro/nano CeO2 and new carbon materials (MWNTs, graphene) on enhancing electrochemical signal were demonstrated, and a bright prospect of micro/nano octahedron CeO2 on electrochemical application can be seen from this paper.