Zhiyu Liu,Liang Chen,Congcong Piao,Jianhe Tang,Yu Liu,Yitong Lin,Dawei Fang,Jun Wang
A novel Z-scheme WO 3 :Yb 3+ ,Er 3+ /Ag/Ag 3 VO 4 /Ag photocatalyst is prepared via hydrothermal and calcination methods. In this system, WO 3 :Yb 3+ ,Er 3+ is used as an excellent up-conversion luminescent agent and highly active photocatalyst to broaden the light response range. Ag with SPR effect is regarded as electronic channel and cocatalyst to accelerate electron transfer and increase hydrogen production. The photocatalytic performance of Z-scheme WO 3 :Yb 3+ ,Er 3+ /Ag/Ag 3 VO 4 /Ag photocatalyst is assessed by levofloxacin degradation with synchronous hydrogen production. Some influence factors, sunlight irradiation time, sacrificial agent concentration and catalyst cycle number, are discussed. The emission light spectrum and energy conversion mechanism of WO 3 :Yb 3+ ,Er 3+ are studied. The photocatalyst gives prominent degradation ratio (90.44 %) and hydrogen production amount (489.02 μmol/g) under sunlight irradiation for 180 min. It shows a high stability and reusability in levofloxacin degradation with synchronous hydrogen production within five cycles. The possible mechanism of levofloxacin degradation with synchronous hydrogen production caused by Z-scheme WO 3 :Yb 3+ ,Er 3+ /Ag/Ag 3 VO 4 /Ag photocatalyst is proposed.
Mengjia Zhang,Changchun Ding,Bin Duan,Yuxiang Wu,Yongqiang Li,Jin Wei,Fengyi Wang,Junshan Hu
The upconversion luminescence (UCL) of inorganic materials doped with activators and sensitizers has great application, but its luminescence intensity always impose restrictions on its development. Herein, an obvious enhancement in luminescence intensity of the WO 3 : Yb 3+ , Ho 3+ phosphor was realized through non-equivalence substitution of Bi 3+ ions. The single pure phase of the synthesized WO 3 : Yb 3+ , Ho 3+ , and Bi 3+ phosphors has been confirmed by the XRD pattern. The morphology of phosphors and valence state of elements have been performed by SEM and XPS techniques. The sample on excitation with 980 nm performs forceful green emission and weak red emission at 543 nm and 662 nm, separately. The concentrations for doped Yb 3+ and Ho 3+ to obtain the optimal UCL in WO 3 are 8% and 1%, respectively. The optimized doping concentration for Bi 3+ ions is 3%. Compared to samples without Bi 3+ ions, the Yb 3+ /Ho 3+ /Bi 3+ doped WO 3 obtains 1.59 and 2.33 times increase in emission intensity of green and red, respectively. We also explored the UCL mechanism and enhancement mechanism on the basis of the power dependency, the UCL and the downshift luminescence. These results based on Yb 3+ /Ho 3+ UCL phosphors research is of great significance.
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