Fayun Li

A simple and efficient method to prepare a phosphorus modified g-C3N4 visible light photocatalyst

Phosphorus doped g-C3N4 was prepared by a simple method using dicyandiamide monomer and diammonium hydrogen phosphate as precursors. X-ray diffraction (XRD), UV-Vis spectroscopy, Fourier transform infrared spectra (FT-IR), photoluminescence (PL), X-ray photoelectron spectroscopy (XPS) and photocurrent measurement were used to characterize the prepared catalysts. The results indicated that the introduction of phosphorus inhibited the crystal growth of graphitic carbon nitride, decreased the band gap energy and increased the separation efficiency of photogenerated electrons and holes. The P doping site is influenced by the phosphorus source. Interstitial P doping is more effective in improving the photocatalytic activity of Rhodamine B (RhB) degradation compared with substitutional P doping. A possible mechanism was proposed.

The influence of preparation method, nitrogen source, and post-treatment on the photocatalytic activity and stability of N-doped TiO2 nanopowder.

NH(3) plasma, N(2) plasma, and annealing in flowing NH(3) were used to prepare N doped TiO(2), respectively. XRD, UV-vis spectroscopy, N(2) adsorption, FT-IR, Zeta-potential measurement, and XP spectra were used to characterize the prepared TiO(2) samples. The nitridation procedure did not change the phase composition and particle sizes of TiO(2) samples, but extended its absorption edges to the visible light region. The photocatalytic activities were tested in the degradation of an aqueous solution of a reactive dyestuff, methylene blue, under visible light. The photocatalytic activity and stability of TiO(2) prepared by NH(3) plasma were much higher than that of samples prepared by other nitridation procedures. The visible light activity of the prepared N doped TiO(2) was improved by increasing the lattice-nitrogen content and decreasing adsorbed NH(3) on catalyst surface. The lattice-nitrogen stability of N-doped TiO(2) samples improved after HCl solution washing. The possible mechanism for the photocatalysis was proposed.

Construction of g-C3N4/S-g-C3N4 metal-free isotype heterojunctions with an enhanced charge driving force and their photocatalytic performance under anoxic conditions

In heterojunction catalysts, the potential difference is the main driving force for efficient charge separation and transfer. The slight difference in the electronic band structure of the isotype heterojunction catalysts causes a poor driving force, leading to a dissatisfactory charge separation efficiency. In this work, g-C3N4/S-g-C3N4 metal-free isotype heterojunction catalysts (GCN–SCN) with an enhanced charge driving force were prepared by a two step calcination method. Anoxic photocatalytic degradation of RhB under visible light was used to evaluate the performance of the as-prepared g-C3N4 catalysts. The results indicate that this two step calcination method can markedly improve the charge driving force of the as-prepared isotype heterojunctions, leading to a more efficient charge-carrier migration. GCN–SCN displays the highest reaction rate constant of 0.0228 min−1, which is 3.5 and 2.9 times higher than that of GCN/SCN(1) and GCN/SCN(2) prepared by a one step calcination method. A linear relationship is observed between the VB driving force and RhB degradation rate. This paper provides a new perspective to prepare isotype heterojunctions with an improved charge driving force and photocatalytic performance.

Photofixation of atmospheric nitrogen to ammonia with a novel ternary metal sulfide catalyst under visible light

A novel ternary metal sulfide photocatalyst Mo0.1Ni0.1Cd0.8S was prepared for photofixation of atmospheric nitrogen to ammonia under visible light. Characterization results indicate that the obtained catalyst is Mo and Ni co-doped CdS with many sulfur vacancies, not a mixture of MoS2, NiS and CdS. The sulfur vacancies on Mo0.1Ni0.1Cd0.8S not only serve as active sites to adsorb and activate N2 molecules but also promote interfacial charge transfer from Mo0.1Ni0.1Cd0.8S to N2 molecules, thus significantly improving the nitrogen photofixation ability. The concentration of sulfur vacancies plays a significantly important role in the N2 photofixation ability. A possible mechanism was proposed.

Variation of temperature, precipitation and runoff depth enfluencing water contamination in Liao River basin, China

Temporal and spatial variation in temperature, precipitation and runoff depth in Liao River basin, China, during the period of 1969-2009 was investigated. The analysis results revealed a general pattern of increase in temperatures, and decreases in precipitations and runoff depths in Liao River basin. As a result of the reduction of runoff depth coupling with the increase of pollutants discharging, water contamination was exacerbated. Therefore, runoff depth was one of the important factors influencing the water contamination. The spatial variation of annual mean temperature was more obvious from the west to the east, especially in the central plain, and the temperature in the middle of the region was higher than that in the sides of the region. The spatial variation of annual mean precipitation was increasing from the west to the east, and the runoff depth had a similar pattern with the precipitation.