CdS/LaFeO_(3) heterojunctions with improved optical properties for visible-light catalytic applications

Construction of heterojunctions is a normal and effective strategy to improve the photocatalytic performances of semiconductors,through which both the lifetime and the redox ability of electrons/holes can be improved,as co mpared to the respective component.On this basis,we constructed Z-scheme CdS/LaFeO_(3) heterojunctions(CdS/LFO),by in-situ growing different amounts of CdS on the surface of LaFeO_(3),for photocatalytic degradation of tetracycline hydrochloride(TC)in aqueous solution at room temperature.The crystal structure,surface morphology and optoelectronic properties of the COS/LFO heterojunctions were systemically characterized to correlate the reaction activity.Photocatalytic tests indicate that the CdS/LFO heterojunctions exhibit promising activity for TC degradation under visible light irradiation(λ≥420 nm),with 85%TC conversion obtained at reaction time of 45 min,which is 3.4 and 1.9 times higher than that of CdS and LaFeO_(3).The CdS/LFO heterojunctions are also stable in the reaction and can be reused for four cycles with no appreciable activity loss.The applicability of CdS/LFO to photocatalytic degradation of organic dyes,as well as the reaction mechanism,was also explored.

Effect of preparation method on physicochemical properties and catalytic performances of LaCoO3 perovskite for CO oxidation

Perovskite oxides LaCoO3 prepared by templating,co-precipitation and sol-gel method with different complexants were systematically characterized and its catalytic performances for CO oxidation were investigated.The samples were characterized by X-ray diffraction,thermogravimetry analysis and differential scanning calorimetry,N2 physisorption,transmission electron microscopy,temperature program reduction of hydrogen,temperature program desorption of oxygen and X-ray photoelectron spectroscopy measurement,results of which show that the properties of LaCoO3,such as surface morphology,surface area,surface compositions,redox capability,oxygen vacancy,as well as the calcination temperature and formation mechanism,depend intimately on the preparation method.Catalytic tests indicate that the sample prepared by carbon templating method shows the best activity for CO oxidation,with full CO conversion obtained at 135℃.In particular,the catalyst can be activated and significant increase of activity can be obtained with the increase of reaction time.The cyclic and longterm stability of catalysts were discussed and compared.

Cooperative effect between copper species and oxygen vacancy in Ce_(0.7−x)Zr_(x)Cu_(0.3)O_(2) catalysts for carbon monoxide oxidation

The effects of Zr doping on the existence of Cu and the catalytic performance of Ce_(0.7−x)Zr_(x)Cu_(0.3)O_(2)for CO oxidation were investigated.The characterization results showed that all samples have a cubic structure,and a small amount of Zr doping facilitates Cu^(2+) ions entering the CeO2 lattice,but excessive Zr doping leads to the formation of surface CuO crystals again.Thus,the number of oxygen vacancies caused by the Cu^(2+) entering the lattice(e.g.,Cu^(2+)-□-Ce^(4+);□:oxygen vacancy),and the amount of reducible copper species caused by CuO crystals,varies with the Zr doping.Catalytic CO oxidation tests indicated that the oxygen vacancy and the reducible copper species were the adsorption and activation sites of O_(2)and CO,respectively,and the cooperative effects between them accounted for the high CO oxidation activity.Thus,the samples x=0.1 and 0.3,which possessed the most oxygen vacancy or reducible copper species,showed the best activity for CO oxidation,with full CO conversion obtained at 110℃.The catalyst is also stable and has good resistance to water during the reaction.

Molecular genetic analysis of Dongzhou-period ancient human of Helingeer in Inner Mongolia,China

The mtDNA hypervariable region I(HVR-I)of 10 ancient individuals from Dongzhou-period ancient human populations in Helingeer county of Inner Mongolia were amplified and sequenced to investigate the genetic structure.The relationships between the ancient population and related extant populations,as well as its possible origin at the molecular level,were also studied.Moreover,phylogenetic analysis and multi-dimensional scaling analysis were also performed based on the mtDNA data of the ancient population in Helingeer and the related Eurasian population.The results showed that the ancient population in Helingeer were closer to the northern Asian populations than to the other compared populations in matrilineal lineage.Combining the research results of archaeology and anthropology as well as molecular biology,we inferred that they were nomads who migrated from Mongolia plateau and cis-Baikal region to Helingeer in Inner Mongolia,China.