Simple one-step synthesis of coil-like cobalt zirconium phosphate microspheres and the application as photocatalyts
Introduction
Transition metal zirconium phosphates are always used as catalytic materials, such as selective oxidation of alcohols to ketones or aldehydes (NiZr(PO4)2 and CuZr(PO4)2) [1], [2], acetylation of alcohols and phenols (ZnZr(PO4)2) [3], decomposition of butan-2-ol (AgZr2(PO4)3) [4] and oxidation dehydrogenation of cyclohexene (CuZr(PO4)2) [5] and so on. However, the photocatalytic properties of transition metal zirconium phosphates have not been studied more. Shinji Inagaki [6] pointed out that the complex influences of one metallic species on another may result in unusual physical and chemical properties in a bimetallic system. He prepared zirconium-titanium phosphates and used them as considerable photocatalysts to decompose water for H2 generation. Furthermore, phosphates used as photocatalysts have many advantages. The negatively charged phosphate anion can attract the photogenerated holes to the surface by electrostatic force, which is favorable for electrons and holes separation [7]. Thus, much more photogenerated carriers can be involved in redox reactions. Besides, polymetallic materials can be excited by UV light to produce photocarriers [8], [9], [10]. Based on the above findings, an attempt was made to study the photocatalytic properties of zirconium cobalt phosphate under UV light irradiation.
Several methods for the preparation of transition metal zirconium phosphates have been reported, such as ion-exchange method [11], hydrothermal method [12] and deposition-calcination method [4], etc. However, all the methods need several steps or further treatment with harsh reaction conditions. The research for a mild method that can overcome those limitations is necessary. It is well known that microwave is widely used to prepare inorganic materials because of its effective and unique heating mean [13]. The special heating mode can increase the reaction rates and reduce the reaction activation energy. As a result, the products can be obtained at a lower temperature, lower pressure and shorter time. Through the homogeneous reaction, the raw materials mixed evenly in aqueous solution, the selective heating of microwave was benefit for the metal ions uniformly distributing in the target products with special morphologies [14].
In the present work, a simple one-step synthesized method was reported for m-CZPs via microwave-assisted heating at a mild reaction condition of low temperature (90 °C) and atmospheric pressure. The structure, morphology, optical property and adsorption property were investigated in detail. Then, the photocatalytic performance of m-CZPs was evaluated by the degradation of MB solution under UV light irradiation.
Section snippets
Experimental
In a typical synthesis, ZrOCl2 aqueous solution was first added to a flask and CoCl2, NH4F and NaH2PO4 aqueous solutions were then slowly added into the flask in turn. The concentration of Zr4+ in 100 mL solution was 0.005 mol/L. The molar ratios of n(Zr)/n(Co), n(F)/n(Zr) and n(Zr)/n(P) were 1:1, 6:1 and 1:20, respectively. The mixed solution was placed in a microwave reactor and treated at 90 °C for 30 min (500 W) with stirring. The pink precipitate was centrifuged, washed with deionized
Results and discussion
Fig. 1a showed the XRD patterns of m-CZPs. The characteristic peaks of m-CZP0 illustrated that it was amorphous. Other m-CZPs (m-CZP15, m-CZP30 and m-CZP60) could be assigned to a pure monoclinic phase of CoZr(PO4)2·4H2O (JCPDS File No. 31-0447).
The contents of main elements in m-CZP30 were measured by ICP-AES and the results were listed in Table 1. The average molar ratio of n(Co):n(Zr):n(P) = 1:1.08:1.99 in m-CZP30, which equaled approximately to 1:1:2 in the formula of CoZr(PO4)2.
The XPS of
Conclusions
In summary, porous coil-like m-CZPs were successfully prepared by the microwave-assisted heating method in one-step under the mild conditions of low temperature and normal atmosphere. The three-dimensional microstructure may form on the molecular framework which caused by the bonding mode of metal ions (cobalt and zirconium) and phosphates. The photocatalytic experiments showed that the absorption and degradation efficiencies of m-CZP60 were both higher than m-CZP15 and m-CZP30. Moreover, the
Declaration of Competing Interest
The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
Acknowledgments
This work was supported by the Ministry of Science and Technology of the People's Republic of China (ID 2012BAK30B03) and the Fundamental Research Funds for the Central Universities (Nos. 2232013A3-05 and CUSF-DH-D-2014036).
References (17)
- et al.
Chin. J. Catal.
(2015) - et al.
Chin. J. Catal.
(2014) - et al.
J. Catal.
(1996) - et al.
J. Catal.
(1986) - et al.
Appl. Surf. Sci.
(2017) - et al.
Mater. Lett.
(2019) - et al.
Mater. Lett.
(2017) - et al.
Mater. Lett.
(2015)
Cited by (3)
Mesoporous silver-cobalt-phosphate nanostructures synthesized via hydrothermal and solid-state reaction for supercapattery devices
2022, International Journal of Energy ResearchRevisiting the Old and Golden Inorganic Material, Zirconium Phosphate: Synthesis, Intercalation, Surface Functionalization, and Metal Ion Uptake
2020, Industrial and Engineering Chemistry Research