Zn-Ti layered double oxide (LDO) nanosheets were synthesized by a simple co-precipitation-calcination process for the enhanced photocatalytic degradation of methyl orange (MO), rhodamine B (RhB) and methylene blue (MB). ZnTi-LDOs nanosheets present higher photocatalytic efficiency for MO, RhB and MB removal, which is 5.4, 4.4 and 6.7 times of that of Zn-Ti layered double hydroxide (LDH), respectively. The photocatalytic activity of synthesized ZnTi-LDOs is greatly affected by the mole ratio of Zn/Ti, calcination temperature and pH value. It is found that the formation of ZnO/ZnTiO 3 heterojunction in ZnTi-LDOs could effectively accelerate the rapid separation of charge carriers, and thus enhance the photocatalytic activity via enlarging the photoresponse range. The possible charge transfer mechanism for photocatalytic degradation of organic dyes by ZnTi-LDOs was proposed based on the active species test and UV–Vis diffuse reflectance spectra. The results of active species trapping experiments showed that ‧OH, ‧O 2 − , h + , e − all had effect on the degradation of RhB , and ‧OH played a major role. This study provides a new insight for the photocatalytic degradation of organic pollutants from wastewater by ZnTi-LDOs.
Zhiyu Liu,Jianhe Tang,Congcong Piao,Xing Zhang,Xiaochen Qi,Ying Tian,Dawei Fang,Jun Wang
A novel Z-scheme CaF 2 :Yb 3+ ,Er 3+ @ZnTiO 3 /Au/CdS photocatalyst has been prepared. In this system, an excellent up-conversion luminescent agent, CaF 2 :Yb 3+ ,Er 3+ , is introduced to broaden the light response range. The Au surface plasmon resonance effect endows the system with highly efficient charge transfer. The photocatalytic activity of the Z-scheme CaF 2 :Yb 3+ ,Er 3+ @ZnTiO 3 /Au/CdS photocatalyst has been evaluated in the degradation of norfloxacin (NOR) with simultaneous hydrogen production . Some influencing factors, such as solar light irradiation time, sacrificial agent concentration, and number of reuse cycles, are discussed. The emission spectrum and energy conversion mechanism of CaF 2 :Yb 3+ ,Er 3+ have also been studied. The prepared photocatalyst facilitated a significant degree of degradation (92.05%) of NOR and considerable hydrogen production (513.39 μmol/g) under solar light irradiation for 5.0 h. Moreover, it showed high stability in photocatalytic NOR degradation with simultaneous hydrogen production over five cycles. A possible mechanism for photocatalytic degradation of NOR with simultaneous hydrogen production promoted by the Z-scheme CaF 2 :Yb 3+ ,Er 3+ @ZnTiO 3 /Au/CdS photocatalyst is proposed.
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