Synthesis of one-dimensional TiO2/V2O5 branched heterostructures and their visible light photocatalytic activity towards Rhodamine B

Electrospun metal oxide-TiO2 nanofibers for elemental mercury removal from flue gas

Nanofibers prepared by an electrospinning method were used to remove elemental mercury (Hg(0)) from simulated coal combustion flue gas. The nanofibers composed of different metal oxides (MO(x)) including CuO, In(2)O(3), V(2)O(5), WO(3) and Ag(2)O supported on TiO(2) have been characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), energy dispersing X-ray (EDX) and UV-vis spectra. The average diameters of these nanofibers were about 200nm. Compared to pure TiO(2), the UV-vis absorption intensity for MO(x)-TiO(2) increased significantly and the absorption bandwidth also expanded, especially for Ag(2)O-TiO(2) and V(2)O(5)-TiO(2). Hg(0) oxidation efficiencies over the MO(x)-TiO(2) nanofibers were tested under dark, visible light (vis) irradiation and UV irradiation, respectively. The results showed that WO(3) doped TiO(2) exhibited the highest Hg(0) removal efficiency of 100% under UV irradiation. Doping V(2)O(5) into TiO(2) enhanced Hg(0) removal efficiency greatly from 6% to 63% under visible light irradiation. Ag(2)O doped TiO(2) showed a steady Hg(0) removal efficiency of around 95% without any light due to the formation of silver amalgam. An extended experiment with 8 Hg(0) removal cycles showed that the MO(x)-TiO(2) nanofibers were stable for removing Hg(0) from flue gas. Factors responsible for the enhanced photocatalytic activities of the MO(x)-TiO(2) nanofibers were also discussed.

AgIO3-modified AgI/TiO2 composites for photocatalytic degradation of p-chlorophenol under visible light irradiation

Semiconducting silver iodate (AgIO(3)) was used to modify the visible light response of an AgI/TiO(2) (AIT) catalyst by a facile method. The uncalcined AIT (AITun) and AIT calcined at 200°C (AIT200) consisted of AgIO(3), AgI, and TiO(2) semiconductors, while that calcined at 450 °C (AIT450) was composed of AgI and TiO(2). The activity in p-chlorophenol (PCP) degradation under visible light irradiation using either AITun or AIT200 was much higher than that with AIT450, which was mainly attributed to the fact that the presence of AgIO(3) provided a new matching band potential. AIT200 exhibited better photocatalytic properties than AITun due to its higher crystallinity after calcination. Moreover, the high catalytic activity of AIT200 was maintained after five successive cyclic experiments under visible irradiation. Considering the effect of radical scavengers and N(2) purging on the photocatalysis process, we deduced that the probable pathway of PCP degradation was mainly a surface charge process, caused by valence band holes.