Preparation of palygorskite-Cd0.5Zn0.5S/Zn-Fe LDH composite and its photocatalytic performance
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摘要: 为解决Cd0.5Zn0.5S易光腐蚀的缺点,两步水热法制备了坡缕石(PGS)负载Cd0.5Zn0.5S/Zn-Fe 层状双金属氢氧化物(LDH)复合材料(PGS-Cd0.5Zn0.5S/Zn-Fe LDH),通过Zn-Fe LDH和PGS提高光生载流子的分离效率。利用XRD、SEM、TEM、UV-Vis DRS和PL对材料的结构、形貌及光学性能进行了表征。电镜图像显示,片状Zn-Fe LDH表面附着针状PGS与颗粒状Cd0.5Zn0.5S。紫外-可见漫反射光谱表明PGS-Cd0.5Zn0.5S/Zn-Fe LDH吸光区域比Cd0.5Zn0.5S宽,吸收边缘从560 nm红移至605 nm。PGS-Cd0.5Zn0.5S/Zn-Fe LDH在光催化降解结晶紫(CV)中表现出良好的光催化活性,催化活性高于Cd0.5Zn0.5S和Zn-Fe LDH。当PGS 与Cd0.5Zn0.5S/Zn-Fe LDH质量比为50%时,可见光照射60 min, 20 mg PGS-Cd0.5Zn0.5S/Zn-Fe LDH对20 mg/L结晶紫溶液的去除率为97.5%,
${\text{•}} {\rm{O}}_2^{-}$ 、•OH是光催化降解的主要活性物种,且5次循环实验后仍然保持较高活性。此外,制备的复合材料对孔雀石绿(MG)、酸性品红(AF)、罗丹明B(RhB)、甲基橙(MO)、亚甲基蓝(MB)等染料均表现出较好的光降解效果。-
关键词:
- Cd0.5Zn0.5S/Zn-Fe LDH /
- 坡缕石 /
- 光催化剂 /
- 降解 /
- 染料
Abstract: To solve easy photocorrosion of Cd0.5Zn0.5S, palygorskite (PGS) supported Cd0.5Zn0.5S/Zn-Fe layered double hydroxides (LDH) composites (PGS-Cd0.5Zn0.5S/Zn-Fe LDH) were prepared by a two-step hydrothermal method. The aim is to improve the separation efficiency of photogenerated carriers using Zn-Fe LDH and PGS. Its crystal phase, micromorphology and optical properties were characterized by XRD, SEM, TEM, UV-Vis DRS and PL. The electron microscope images show that the needle-like PGS and graininess Cd0.5Zn0.5S are attached on the surface of Zn-Fe LDH. UV-visible diffuse reflectance spectroscopies confirm that the PGS-Cd0.5Zn0.5S/Zn-Fe LDH has a wider absorption range than Cd0.5Zn0.5S. That absorption range has a red shift from 560 nm to 605 nm. The photocatalytic activity of PGS-Cd0.5Zn0.5S/Zn-Fe LDH is higher than those of Cd0.5Zn0.5S and Zn-Fe LDH in the degradation of crystal violet. The photocatalyst with mass ratio of PGS to Cd0.5Zn0.5S/Zn-Fe LDH of 50%, the removal rate of 20 mg/L crystal violet is 97.5% by 20 mg of PGS-Cd0.5Zn0.5S/Zn-Fe LDH for 60 min.${\text{•}}{\rm{O}}_2^{-} $ and •OH groups are the main active species in photodegradatlon reaction. The photocatalytic activity of composite is well retained after five cycles. Meanwhile, the composite shows good photocatalytic activity in the degradations of various dyes including malachite green (MG), acid fuchsin (AF), Rhodamine B (RhB), methyl orange (MO) and methylene blue (MB).-
Key words:
- Cd0.5Zn0.5S/Zn-Fe LDH /
- palygorskite /
- photocatalyst /
- degradation /
- dye
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图 2 Zn-Fe LDH (a)、Cd0.5Zn0.5S (b)、Cd0.5Zn0.5S/Zn-Fe LDH 3 (c)、PGS (d)和50%PGS-Cd0.5Zn0.5S/Zn-Fe LDH 3 (e)的SEM图像;50%PGS-Cd0.5Zn0.5S/Zn-Fe LDH 3的TEM图像((f), (g))及EDS能谱图(h)
Figure 2. SEM images of Zn-Fe LDH (a), Cd0.5Zn0.5S (b), Cd0.5Zn0.5S/Zn-Fe LDH 3 (c), PGS (d) and 50%PGS-Cd0.5Zn0.5S/Zn-Fe LDH 3 (e); TEM images ((f), (g)) and EDS spectrum (h) of 50%PGS-Cd0.5Zn0.5S/Zn-Fe LDH 3
图 5 Cd0.5Zn0.5S、Zn-Fe LDH和Cd0.5Zn0.5S/Zn-Fe LDH复合材料对染料的光催化活性((a), (b))及光催化降解反应动力学(c)
Figure 5. Photocatalytic activity of Cd0.5Zn0.5S, Zn-Fe LDH and Cd0.5Zn0.5S/Zn-Fe LDH composites for dyes ((a), (b)) and photocatalytic degradation reaction kinetics (c)
Ct—Concentration after time t of degradation; C0—Initial concentration; MB—Methylene blue; CV—Crystal violet; RhB—Rhodamine B; AF—Acid fuchsin; MG—Malachite green; MO—Methyl orange
表 1 Cd0.5Zn0.5S/Zn-Fe层状双金属氢氧化物(LDH)复合材料的命名
Table 1. Nomenclature of Cd0.5Zn0.5S/Zn-Fe layered double hydroxides (LDH) composites
Sample Mass of Zn-Fe LDH/g Mass ratio of Cd0.5Zn0.5S to
Zn-Fe LDHCd0.5Zn0.5S/Zn-Fe LDH 1 0.052 7∶1 Cd0.5Zn0.5S/Zn-Fe LDH 2 0.104 7∶2 Cd0.5Zn0.5S/Zn-Fe LDH 3 0.156 7∶3 Cd0.5Zn0.5S/Zn-Fe LDH 4 0.208 7∶4 Cd0.5Zn0.5S/Zn-Fe LDH 5 0.260 7∶5 表 2 坡缕石(PGS)-Cd0.5Zn0.5S/Zn-Fe LDH复合材料的命名
Table 2. Naming of palygorskite (PGS)-Cd0.5Zn0.5S/Zn-Fe LDH composites
Sample Mass ratio of PGS/wt% Mass ratio of Cd0.5Zn0.5S/
Zn-Fe LDH 3/wt%30%PGS-Cd0.5Zn0.5S/
Zn-Fe LDH 330 100 40%PGS-Cd0.5Zn0.5S/
Zn-Fe LDH 340 100 50%PGS-Cd0.5Zn0.5S/
Zn-Fe LDH 350 100 60%PGS-Cd0.5Zn0.5S/
Zn-Fe LDH 360 100 -
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