Three different nanorod-like gallium oxides with mono/poly-crystalline nature(α, β, and α/β-Ga2O3) were prepared by regulating the amount of polyethylene glycol(PEG) 6000 in the range of 0.2–0.8 g proportionally via a hydrothermal method combined with further calcination. The bandgap of the products, given by UV-Vis diffuse reflectance spectra(UV-Vis DRS), was in the order of α-Ga2O3 > α/β-Ga2O3 > β-Ga2O3. To further investigate the photocatalysis performance of the catalysts, the decomposition of rhodamine B(Rh B) by Ga2O3 under UV light illumination(λ < 387 nm) was presented and complete degradation could be achieved within 30 min, a result that showed the highest efficiency. The photocatalytic oxidation mechanism is further discussed and prominently related to the active species: hydroxyl radical(·OH) and superoxide radical(O·-2), which were confirmed by electron paramagnetic resonance(EPR).
Microcystin-RR（MC-RR）,a form of microcystin with two arginine moieties,is a cyanobacterial toxin that has been detected across a wide geographic range.It is a great concern globally because of its potential liver toxicity.Herein,the abilities of BiVO4,Ag-BiVO4,Ag2O-BiVO4 and Ag/Ag2O-BiVO4 to photocatalytically degrade MC-RR under visible-light irradiation（λ≥420 nm） were investigated and compared.The possible degradation pathways were explored through analysis of the reaction intermediates by high-performance liquid chromatography-mass spectrometry.The results showed that the presence of Ag^0 enhanced the photocatalytic efficiency of Ag/Ag2O-BiVO4 via a synergetic effect between Ag2O and Ag^0 at the p-n heterojunction.Moreover,the presence of Ag^0 also greatly promoted the adsorption of MC-RR on the photocatalyst surface.Toxicological experiments on mice showed that the toxicity of MC-RR was significantly reduced after photocatalytic degradation.
A hydrophobic complex of Cu2＋[bis-salicylic aldehyde-o-phenylenediamine], Cu-SPA, was prepared and used as a heterogeneous photocatalyst to degrade organic pollutants in water under visible irradiation （λ≥420 nm） at neutral pH. The structure of complex was characterized by using nuclear magnetic resonance （NMR）, elemental analysis, IR and UV-vis spectrometries. Degradation of Rhodamine B （RhB）, Sulforhodamine B （SRB） and Benzoic acid （BA） in water were used as model reactions to evaluate the photocatalytic activities of Cu-SPA. The results indicated that RhB and SRB were easily adsorbed on the hydrophobic surface of Cu-SPA from aqueous solution （the maximum adsorption amount： Qmax = 11.09 and 8.05 μmol/g, respectively）. Under visible irradiation, RhB and SRB were decolorized completely after 210 and 240 min, respectively, and BA was removed completely after 5 h. The efficiency of H202 was 〉 95%, in contrast to that of the reaction without catalyst or light （〈 20%）. In water soluble medium, the hydrophobic Cu-SPA can be used more than 6 cycles. ESR results and the behavior of cy- clic voltammetry showed that, in the reaction process, Cu2＋-SPA was reduced to intermediate state Cu＋-SPA firstly, which was extremely unstable and reacted rapidly with H2O2, leading to high reactive oxygen species （.OH radical ） to degrade the substrate.
SONG QuanJIA ManKeMA WanHongFANG YanFenHUANG YingPing
