Ni(NH_(3))_(6)^(2+) more efficient than Ni(H_(2)O)_(6)^(2+) and Ni(OH)_(2) for catalyzing water and phenol oxidation on illuminated Bi_(2)MoO_(6) with visible light

Nickel (hydr)oxide (NiOH) is known to be good co-catalyst for the photoelectrochemical oxidation of water,and for the photocatalytic oxidation of organics on different semiconductors.Herein we report a greatly improved activity of Bi_(2)MoO_(6)(BMO) by nickel hexammine perchlorate (NiNH).Under visible light,phenol oxidation on BMO was slow.After NiNH,NiOH,and Ni^(2+)loading,a maximum rate of phenol oxidation increased by factors of approximately 16,8.8,and 4.7,respectively.With a BMO electrode,all catalysts inhibited O_(2)reduction,enhanced water (photo-)oxidation,and facilitated the charge transfer at solidliquid interface,respectively,the degree of which was always NiNH>NiOH>Ni^(2+).Solid emission spectra indicated that all catalysts improved the charge separation of BMO,the degree of which also varied as NiNH>NiOH>Ni^(2+).Furthermore,after a phenol-free aqueous suspension of NiNH/BMO was irradiated,there was a considerable Ni(Ⅲ) species,but a negligible NH_(2)radical.Accordingly,a plausible mechanism is proposed,involving the hole oxidation of Ni(Ⅱ) into Ni(Ⅳ),which is reactive to phenol oxidation,and hence promotes O_(2)reduction.Because NH_(3)is a stronger ligand than H_(2)O,the Ni(Ⅱ) oxidation is easier for Ni(NH_(3))6+than for Ni(H_(2)O)6+.This work shows a simple route how to improve BMO photocatalysis through a co-catalyst.

Fabrication, adsorption and photocatalytic properties of ZnTi0.6Fe1.4O4/Carbon nanotubes composites

ZnTixFe2-xO4 and ZnTi0.6Fe1.4O4/Carbon nanotubes （ZT0.6F1.4/CNTs） composites were prepared by chemical co-precipitation method. The composition, microstructure, magnetic property, adsorption and photocatalytic activity of the prepared samples were characterized by means of modem analytical techniques. The results indicated that ZT0.6F1.4CNTs composites not only held the original special structure and excellent adsorption properties of CNTs, but also had suitable magnetic property and excellent photocatalytic activity. The removal rate of the samples on Rhodamine B （RhB） depended on the adsorption of CNTs and the photocatalytic degradation of ZTo.6F1.4 in the composites. The maximum adsorption amount （qm） of ZT0.6F1.4/CNTs with the mass ratios of ZT0.6F1.4 to CNTs （mz/c）=l was up to 17.153 mg g-t for RhB, its adsorption behavior was in accord with Langmuir model, and its photocatalytic degradation activity on RhB had a positive correlation with the content of ZT0.6F1.4 in the sample. The experimental results indicate that the total removal rate of composite with rnz/c=l on RhB was more than 95% and the composite had good decontamination capability on industrial dye wastewater. In addition, the samples can be recovered conveniently, activated easily and had good performance for recycling.