Sinong Wang

A nanoporous molybdenum carbide nanowire as an electrocatalyst for hydrogen evolution reaction

A highly active and stable electrochemical catalyst of nanoporous molybdenum carbide nanowires (np-Mo2C NWs) has been developed for hydrogen evolution reaction (HER). The np-Mo2C NWs were synthesized simply by pyrolysis of a MoOx/amine hybrid precursor with sub-nanosized periodic structure under an inert atmosphere. The enriched nanoporosity and large reactive surface of these highly dispersed nanowires with uniform Mo2C nanocrystallites provide an efficient electrocatalysis, leading to their superior HER activity with lower onset overpotential and higher current densities than Mo2C microparticles. This study opens a new perspective for the development of highly active non-noble electrocatalysts for hydrogen production from water splitting.

Controllable synthesis of organic-inorganic hybrid MoOx/polyaniline nanowires and nanotubes.

A novel chemical oxidative polymerization approach has been proposed for the controllable preparation of organic-inorganic hybrid MoO(x)/polyaniline (PANI) nanocomposites based on the nanowire precursor of Mo(3)O(10)(C(6)H(8)N)(2)·2H(2)O with sub-nanometer periodic structures. The nanotubes, nanowires, and rambutan-like nanoparticles of MoO(x)/PANI were successfully obtained through simply modulating the pH values to 2.5-3.5, ≈2.0 and ≈1.0, respectively. Through systematic physicochemical characterization, such as scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, Raman spectroscopy, and so forth, the composition and structure of MoO(x)/PANI hybrid nanocomposites are well confirmed. It is found that the nanowire morphology of the precursor is the key to achieve the one-dimensional (1D) structures of final products. A new polymerization-dissolution mechanism is proposed to explain the formation of such products with different morphologies, in which the match between polymerization and dissolution processes of the precursor plays the important role. This approach will find a new way to controllably prepare various organic-inorganic hybrid 1D nanomaterials especially for polymer-hybrid nanostructures.

Microwave-Assisted Reactant-Protecting Strategy toward Efficient MoS2 Electrocatalysts in Hydrogen Evolution Reaction

The exposure of rich active sites is crucial for MoS2 nanocatalysts in efficient hydrogen evolution reaction (HER). However, the active (010) and (100) planes tend to vanish during preparation because of their high surface energy. Employing the protection by thiourea (TU) reactant, a microwave-assisted reactant-protecting strategy is successfully introduced to fabricate active-site-rich MoS2 (AS-rich MoS2). The bifunctionality of TU, as both a reactant and a capping agent, ensures rich interactions for the effective protection and easy exposure of active sites in MoS2, avoiding the complicated control and fussy procedure related to additional surfactants and templates. The as-obtained AS-rich MoS2 presents the superior HER activity characterized by its high current density (j = 68 mA cm(-2) at -300 mV vs RHE), low Tafel slope (53.5 mV dec(-1)) and low onset overpotential (180 mV), which stems from the rich catalytic sites and the promoted conductivity. This work elucidates a feasible way toward high performance catalysts via interface engineering, shedding some light on the development of emerging nanocatalysts.

Preparation of organic–inorganic hybrid Fe–MoOx/polyaniline nanorods as efficient catalysts for alkene epoxidation

Novel Fe-MoO(x)/polyaniline nanorods were fabricated via in situ polymerization of Mo(3)O(10)(C(6)H(5)NH(3))(2)·2H(2)O nanowires, in which interface reactions remarkably influenced the morphology of products; and the nanorods showed high performance in cyclooctene epoxidation due to the organic-inorganic hybrid structure and Fe(3+) additive.

Electrostatic-induced synthesis of tungsten bronze nanostructures with excellent photo-to-thermal conversion behavior†

A simple one-step hydrothermal route is developed to synthesize one-dimensional (1D) hexagonal tungsten bronze (HTB) nanostructures. The key to this route is utilizing the electrostatic attraction between negatively charged tungstate and protonated ethylenediamine (EDA) to create a special local reductive environment in a non-reductive aqueous solution, which contributes to the in situ reduction of some of the hexavalent tungsten atoms during the 1D growth process and the mixed-valent nature of the final HTB structure. The as-prepared HTB nanomaterials are characterized to be highly crystalline and of uniform 1D morphology. Influences of synthetic conditions, such as the pH value, reaction time, temperature and amount of EDA, are systematically investigated. Meanwhile, this strategy is successfully introduced to prepare a series of metal-doped 1D HTB nanomaterials by simply changing the type of starting alkali tungstate. Experimental evidence reveals that the formation of the products follows an electrostatic-induced reductive nucleation–dissolution–recrystallization process, and the electrostatic interaction between the two oppositely charged species plays an indispensable role in the growth of mixed-valent HTB nanostructures. More importantly, these nanomaterials show efficient transformation of near-infrared light into local heat, indicating their potential applications as a new genre of functional materials in photothermal energy conversion as well as other relevant criteria.