Cerium Oxide Hollow Sphere: Controllable Synthesis and Its Effect on Electrocatalytic Performance of Pt-based Catalysts

doi:10.15541/jim20170379

Abstract

Abstract:

By hydrothermal method using carbon sphere as template, single and double shell CeO₂ hollow spheres were prepared with specific surface area of 124.44 m²/g, 140.95 m²/g, pore volume of 0.014427 cm³/(g·nm), 0.018605 cm³/(g·nm), and pore size distribution in the range of 2 nm-4 nm. The Pt-CeO₂/RGO catalysts were prepared by microwave-assisted reduction of chloroplatinic acid using ethylene glycol, and then the effect of the addition of CeO₂ hollow sphere on the electrocatalytic performance of Pt-based catalysts were investigated. The microstructure and catalysts property of CeO₂were characterized by X-ray diffraction (XRD), specific surface area and pore size analyzer (BET), scanning electron microscopy (SEM)-electron spectroscopy (EDAX), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and the electrochemical performance of the catalysts was tested by electrochemical workstation. The results show that the CeO₂ in the catalyst maintains the original spherical morphology and the Pt nanoparticles are mainly distributed near the CeO₂. When RGO : CeO₂= 1 : 2, the Pt-CeO₂/RGO catalyst with double shell CeO₂ hollow sphere shows the best electrocatalytic activity, with electrochemically active surface area at 94.27 m²/g, peak current density at 613.54 A/g, and the steady-state current density of 1000 s at135.45 A/g.

Key words: direct ethanol fuel cell (DEFC), CeO₂ hollow sphere, anode catalyst, catalytic oxidation capacity, stability

CLC Number:

TM911

GUO Rui-hua, MO Yi-Jie, AN Sheng-Li, ZHANG Jie-Yu, ZHOU Guo-Zhi. Cerium Oxide Hollow Sphere: Controllable Synthesis and Its Effect on Electrocatalytic Performance of Pt-based Catalysts[J]. Journal of Inorganic Materials, 2018, 33(7): 779-786.

Figures/Tables 12

Table 1 Different conditions of seven groups of catalysts

Number	Sample	CeO₂ additive situation	Weight ratio of RGO to CeO₂
1#	Pt-CeO₂/ RGO	Add single shell CeO₂ hollow sphere	RGO:CeO₂=1:1
2#	Pt-CeO₂/ RGO	Add single shell CeO₂ hollow sphere	RGO:CeO₂=1:2
3#	Pt-CeO₂/ RGO	Add single shell CeO₂ hollow sphere	RGO:CeO₂=1:3
4#	Pt-CeO₂/ RGO	Add double shell CeO₂ hollow sphere	RGO:CeO₂=1:1
5#	Pt-CeO₂/ RGO	Add double shell CeO₂ hollow sphere	RGO:CeO₂=1:2
6#	Pt-CeO₂/ RGO	Add double shell CeO₂ hollow sphere	RGO:CeO₂=1:3
7#	Pt/ RGO	Not add CeO₂	-

Fig. 1 XRD patterns of two kinds of CeO2(a) Single shell CeO2; (b) Double shell CeO2

Fig. 2 SEM images of two kinds of CeO2(a) Single shell CeO2; (b) Double shell CeO2

Fig. 3 TEM images of two kinds of CeO2(a) Single shell CeO2; (b) Double shell CeO2

Fig. 4 Nitrogen sorption isotherms and BJH pore size distribution curves of two kinds of CeO2(a) Single shell CeO2; (b) Double shell CeO2

Fig. 5 (a) SEM image , (b-d) plane scan analysis and (e, f) EDS analysis of dot(1) and (2) from (a) for 2# catalyst

Fig. 6 XPS spectra of catalysts(a) Ce3d XPS spectra of 2# catalyst; (b) Pt4f XPS spectra of 2# catalyst; (c) Pt4f XPS spectra of 5# catalyst

Table 2 XPS data and the possible chemical states of catalysts

Sample	Pt (0)/eV	Relative ratio/%	Pt (II)/eV	Relative ratio/%
2#	70.76, 74.07	74.73	71.46, 74.35	25.26
5#	70.90, 74.27	81.93	71.46, 74.27	18.06

Fig. 7 XRD patterns of catalysts

Fig. 8 Cyclic voltammetry curves of catalysts in 0.5 mol/L H2SO4

Fig. 9 Cyclic voltammetry curves of catalysts in 0.5 mol/L H2SO4+1 mol/L C2H5OH(a) Add single shell CeO2; (b) Add double shell CeO2

Fig. 10 I-t curves of catalysts in 1 mol/L CH3CH2OH+ 0.5 mol/L H2SO4 solution

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