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).
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(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 8.05μmol/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 H2O2was>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 cyclic 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
