As an electrocatalyst, conventional 2H-phase MoS 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, MoS heterogeneous-phase nanosheets with a 1T phase (1T/2H-MoS) generated in situ were prepared through a facile hydrothermal method. The locally introduced 1T-phase MoS can not only contribute more active sites but also markedly promote the electronic conductivity. Because of this unique structure, the as-synthesized 1T/2H-MoS nanosheets exhibit remarkable performance for the hydrogen evolution reaction with a small overpotential of 220 mV at 10 mA/cm, 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.

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P-doped TiO 2 nanoparticles were synthesized by the sol-gel method with various H 3 PO 4 amounts. The samples were calcinated at different temperature and charactered by XPS, ICP, XRD, SEM, Raman, FTIR, and UV-vis methods, so that the formation process of phosphate species could be inspected. The XRD results show that P species hinder the particle growth of anatase and increase the anatase-to-rutile phase transformation temperature to more than 900 °C, and a new titanyl phosphate, Ti 5 O 4 (PO 4 ) 4 , was observed in P-doped TiO 2 when calcined at 1000 °C. The UV-vis results indicate that the P species is likely to have two different states, leading to the variety of visible-light photocatalytic activity and band gap energy of P-doped TiO 2 . One state is the "separated phase". In this state, the P/Ti ratio is very low so that the P species is surrounded by TiO 2 . The "separated phase" of P species introduces oxygen into TiO 2 lattice and hence causes a red-shift of the adsorption band edge of anatase, leading to the increased visible-light photocatalytic activity of P-doped TiO 2 . The other state is the "congregated phase". It appears at the micro region where the ratio of P/Ti is high enough to make the TiO 2 clusters isolated by P species. The "congregated phase" of P species acts as the interface phase between TiO 2 clusters and strongly retards the crystal growth of anatase, resulting in the widened band gap of P-doped TiO 2 . Furthermore, a possible mechanism was also proposed to explain the formation of the two phases during the sol-gel process. The results indicate that in order to improve the visible-light photocatalytic activity of P-doped TiO 2 the percentage of "separated phase" in P species needs to be enhanced.

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Perovskite-type LaCoO 3Àx (x ¼ 0$0:075) porous powder was synthesized via citrate sol-gel method. With calcination temperature increasing, its crystal structure changed from LaCoO 3 to LaCoO 2:925 with the increase in oxygen vacancy. The synthesized LaCoO 3Àx contains a large amount of adsorbed oxygen on its surface due to the existence of oxygen vacancy to some extent. Dye degradation activity of LaCoO 3Àx in methyl orange solution was investigated both under the visible light irradiation (>400 nm) and in the dark. LaCoO 3Àx exhibited dye degradation activity in the dark when being preserved in methyl orange solution for a long time caused by the reducibility of Co 3þ in LaCoO 3Àx , and then dye molecule was oxidized gradually and slowly. The degradation rate was improved under the visible light due to the optical property of LaCoO 3Àx in visible light region. After degradation, methyl orange molecule may be decomposed to acetate group in a small amount. After use for a long time, some Co 3þ was reduced to Co 2þ accompanied by the formation of oxygen vacancy, and then LaCoO 3 transformed to LaCoO 2:925 gradually. For LaCoO 3Àx calcined at 800 C, LaCoO 3Àx perovskite skeleton structure was stable, and can be reused in recycle dye degradation.