Maosheng Xia

A high-stability silica-clay composite: synthesis, characterization and combination with TiO2 as a novel photocatalyst for Azo dye.

A novel micro-mesopores composite material has successfully been synthesized at basic hydrothermal conditions using natural mineral montmorillonite (MMT) and tetraethoxysilane (TEOS). Two surfactants, cetyltrimethyl ammonium bromide (CTAB) and polyethylene glycol (PEG), have been employed in order to shape the pores in the composite. The resultant silica-clay has large surface area (472m(2)/g) and high hydrothermal stability, which makes it a potentially host-material for catalyst. The molecular size of different surfactant leads to the multi-peak distribution of pore size, and the surfactant of larger size (PEG) corresponds to the formation of larger pores. Moreover, the photocatalytic results show that, comparing with pure TiO(2) particles, the loaded TiO(2) on such silica-clay shows higher photodegradation rate of methyl orange (MO) in aqueous. And another porous aluminosilicate host, zeolite, was also discussed for comparison.

Heterogeneous Nanostructure Based on 1T Phase MoS2 for Enhanced Electrocatalytic Hydrogen Evolution

As an electrocatalyst, conventional 2H-phase MoS2 suffers from limited active sites and inherently low electroconductivity. Phase transitions from 2H to 1T have been proposed as an effective strategy for optimization of the catalytic activity. However, complicated chemical exfoliation is generally involved. Here, MoS2 heterogeneous-phase nanosheets with a 1T phase (1T/2H-MoS2) generated in situ were prepared through a facile hydrothermal method. The locally introduced 1T-phase MoS2 can not only contribute more active sites but also markedly promote the electronic conductivity. Because of this unique structure, the as-synthesized 1T/2H-MoS2 nanosheets exhibit remarkable performance for the hydrogen evolution reaction with a small overpotential of 220 mV at 10 mA/cm2, a small Tafel slope of 61 mV/decade, and robust stability. This work facilitates the development of a two-dimensional heterogeneous nanostructure with enhanced applications.

Opal promotes hydrothermal carbonization of hydroxypropyl methyl cellulose and formation of carbon nanospheres

Hydrothermal carbon nanospheres were prepared by introducing opal into the hydrothermal carbonization system of hydroxypropyl methyl cellulose (HPMC). Then the effects of opal on hydrothermal carbonization of HPMC were investigated after different reaction durations (105–240 min). The reaction products were characterized by elemental analysis, gas chromatography-mass spectrometry (GC-MS), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), Fourier transform infrared spectroscopy (FT-IR) and N2 adsorption–desorption. Results of elemental analysis indicated that the H (hydrogen) and O (oxygen) content of HPMC decreased through dehydration, demethylation, decarbonylation and hydrolysis reactions, forming hydrochar with higher carbon content. The addition of opal was confirmed to accelerate the hydrolysis of HPMC. N2 adsorption–desorption tests and SEM analysis showed that opal with a large specific surface area adsorbed HPMC hydrolysis products, such as furans, and facilitated furan cyclodehydration on its surfaces to form cross-linked carbons, which contributed to the quick formation of hydrochar. Moreover, the adsorption by opal also inhibited hydrochar aggregation, so the final hydrothermal carbon spheres had sizes of 20–100 nm.