氧化铈空心球可控合成及其对Pt基催化剂电催化性能的影响

doi:10.15541/jim20170379

摘要/Abstract

摘要：

采用水热合成法, 以碳球为模板, 改变焙烧升温速率, 控制影响铈物种的扩散、渗透及碳球结构的收缩率, 制备了单、双壳层CeO₂空心球。通过微波辅助乙二醇还原氯铂酸法制备了Pt-CeO₂/RGO催化剂, 研究了CeO₂空心球的添加对Pt基催化剂电催化性能的影响。利用X射线衍射仪(XRD)、比表面积及孔径分析仪(BET)、扫描电镜(SEM)和电子能谱(EDAX)、透射电镜(TEM)、X射线光电子能谱(XPS)对CeO₂及催化剂的微观结构进行了表征, 利用电化学工作站对催化剂进行电化学性能测试。结果表明: 单、双壳层CeO₂空心球的比表面积为124.44 m²/g、140.95 m²/g, 孔容为0.014427 cm³/(g·nm)、0.018605 cm³/(g·nm), 孔径分布在2~4 nm范围内。催化剂中的CeO₂保持原有的球状形貌, Pt纳米粒子主要分布在CeO₂附近; 当RGO∶CeO₂=1∶2时, 添加了双壳层CeO₂空心球的Pt-CeO₂/RGO催化剂的电催化性能最优, 电化学活性表面积为94.27 m²/g, 对乙醇氧化的峰电流密度值为613.54 A/g, 1000 s的稳态电流密度值为135.45 A/g。

关键词: 直接乙醇燃料电池(DEFC), CeO₂空心球, 阳极催化剂, 催化氧化能力, 稳定性

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

中图分类号:

TM911

郭瑞华, 莫逸杰, 安胜利, 张捷宇, 周国治. 氧化铈空心球可控合成及其对Pt基催化剂电催化性能的影响[J]. 无机材料学报, 2018, 33(7): 779-786.

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.

图/表 12

表1 不同条件的七组催化剂

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	-

图1 两种CeO2的XRD图谱

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

图2 两种CeO2的SEM照片

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

图3 两种CeO2的TEM照片

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

图4 两种CeO2的氮气吸脱附曲线与BJH孔径分布曲线

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

图5 2#催化剂的SEM照片(a)和面扫分析结果(b)~(d)及图(a)中点(1)/(2)的EDS分析结果(e), (f)

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

图6 催化剂的XPS图谱

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

表2 催化剂的XPS图谱分析数据

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

图7 催化剂的XRD图谱

Fig. 7 XRD patterns of catalysts

图8 催化剂在0.5 mol/L H2SO4中的循环伏安曲线

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

图9 催化剂在0.5 mol/L H2SO4+1 mol/L C2H5OH中的循环伏安曲线

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

图10 催化剂在 1 mol/L CH3CH2OH+0.5 mol/L H2SO4溶液中的I-t曲线

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

参考文献 33

[1]	JEON M K, WON J Y, LEE K R,et al.Highly active PtRuFe/C catalyst for methanol electro-oxidation.Electrochemistry Communications, 2007, 9(9): 2163-2166.
[2]	RAHSEPAR M, PAKSHIR M, PIAO Y Z,et al.Synthesis and electrocatalytic performance of high loading active PtRu multiwalled carbon nanotube catalyst for methanol oxidation.Electrochimica Acta, 2012, 71(1): 246-251.
[3]	KANG S, LIM S, PECK D H,et al. Stability and durability of PtRu catalysts supported on carbon nanofibers for direct methanol fuel cells.International Journal of Hydrogen Energy, 2012, 37(5): 4685-4693.
[4]	FENG L G, ZHANG J, CAI W W,et al. Single passive direct methanol fuel cell supplied with pure methanol.Journal of Power Sources, 2011, 196(5): 2750-2753.
[5]	WANG ZHAO-MING, WEI XING, PENG WEI,et al. On-line electrochemical transmission infrared spectroscopic study of Pb2+ enhanced C-C bond breaking in the ethanol oxidation reaction.Acta Phys. -Chim. Sin, 2016, 32(6): 1467-1472.
[6]	JENNINGS P C, POLLET B G, JOHNSTON R L.Theoretical studies of Pt-Ti nanoparticles for potential use as PEMFC electrocatalysts.Physical Chemistry Chemical Physics, 2012, 14(9): 3134-3139.
[7]	COCHELL T, MANTHIRAM A.Pt@PdxCuy/C core-shell electrocatalysts for oxygen reduction reaction in fuel cells.Langmuir, 2012, 28(2): 1579-1587.
[8]	STASSI A, GATTO I, MONFORTE G,et al. The effect of thermal treatment on structure and surface composition of PtCo electro- catalysts for application in PEMFCs operating under automotive conditions.Journal of Power Sources, 2012, 208(15): 35-45.
[9]	BLIZNAKOV S T, VUKMIROVIC M B, YANG L,et al. Pt monolayer on electrodeposited Pd nanostructures: advanced cathode catalysts for PEM fuel cells.Journal of the Electrochemical Society, 2012, 159(9): F501-F506.
[10]	FENG L G, ZHAO X, YANG J,et al. Electrocatalytic activity of Pt/C catalysts for methanol electrooxidation promoted by molybdovanadophosphoric acid.Catalysis Communications, 2011, 14(1): 10-14.
[11]	LI MIN, LUO YUAN, XU WEI-JIA,et al. DMFC anode catalyst Fe3O4@Pt particles: synthesis and catalytic performance.Journal of Inorganic Materials, 2017, 9(32): 917-921.
[12]	ZHOU C M, WANG H J, PENG F,et al. MnO2/CNT supported Pt and PtRu nanocatalysts for direct methanol fuel cells.Langmuir, 2009, 25(13): 7711-7717.
[13]	TIMPERMAN L, FENG Y J, VOGEL W,et al. Substrate effect on oxygen reduction electrocatalysis.Electrochimica Acta, 2010, 26(1): 7558-7563.
[14]	DHAVALE V M, KURUNGOT S.Tuning the performance of low-Pt polymer electrolyte membrane fuel cell electrodes derived from Fe2O3@Pt/C core-shell catalyst prepared by anin situ anchoring strategy.The Journal of Physical Chemistry C, 2012, 116(13): 7318-7326.
[15]	FENG L G, YAN L, CUI Z M,et al. High activity of Pd-WO3/C catalyst as anodic catalyst for direct formic acid fuel cell.Journal of Power Sources, 2011, 196(5): 2469-2474.
[16]	TSIOUVARAS N, MARTINEZ-HUERTA M V, MOLINER R,et al. CO tolerant PtRu-MoOx nanoparticles supported on carbon nanofibers for direct methanol fuel cells.Journal of Power Sources, 2009, 186(2): 299-304.
[17]	ELEZOVIĆ N R, BABIĆ B M, RADMILOVIĆ V R,et al. Pt/C doped by MoOx as the electrocatalyst for oxygen reduction and methanol oxidation.Journal of Power Sources, 2008, 175(1): 250-255.
[18]	BAI Y X, WU J J, XI J Y,et al. Electrochemical oxidation of ethanol on Pt-ZrO2/C catalyst.Electrochemistry Communications, 2005, 7(11): 1087-1090.
[19]	FENG L G, YANG J, HU Y,et al. Electrocatalytic properties of PdCeOx/C anodic catalyst for formic acid electrooxidation.International Journal of Hydrogen Energy, 2012, 37(6): 4812-4818.
[20]	ZHOU J H, HE J P, WANG T,et al. Synergistic effect of Re2O3 (Re=Sm, Eu and Gd) on Pt/mesoporous carbon catalyst for methanol electro-oxidation.Electrochimica Acta, 2009, 54(11): 3103-3108.
[21]	SKORODUMOVA N V, BAUDIN M, HERMANSSON K.Surface properties of CeO2 from first principles.Physical Review B, 2004, 69(7): 1-8.
[22]	SCIBIOH M A, KIM S K, CHO E A,et al. Pt-CeO2/C anode catalyst for direct methanol fuel cells.Applied Catalysis B: Environmental, 2008, 84(3/4): 773-782.
[23]	ZHOU Y, GAO Y F, LIU Y C,et al. High efficiency Pt-CeO2/ carbon nanotubes hybrid composite as an anode electrocatalyst for direct methanol fuel cells.Journal of Power Sources, 2010, 195(6): 1605-1609.
[24]	MASUDA T, FUKUMITSU H, FUGANE K,et al. Role of cerium oxide in the enhancement of activity for the oxygen reduction reaction at Pt-CeOx nanocomposite electrocatalyst - an in situ electrochemical X-ray absorption fine structure study.The Journal of Physical Chemistry C, 2012, 116(18): 10098-10102.
[25]	LIN R, CAO C H, ZHANG H Y,et al. Electro-catalytic activity of enhanced CO tolerant cerium-promoted Pt/C catalyst for PEM fuel cell anode.International Journal of Hydrogen Energy, 2012, 37(5): 4648-4656.
[26]	LIU C W, WEI Y C, WANG K W.Surface condition manipulation and oxygen reduction enhancement of PtAu/C catalysts synergistically modified by CeO2 addition and N2 treatment.The Journal of Physical Chemistry C, 2011, 115(17): 8702-8708.
[27]	LI J Y, XIONG S L, PAN J.Hydrothermal synthesis and electrochemical properties of urchin-like core-shell copper oxide nanostructures.The Journal of Physical Chemistry C, 2010, 114(21): 9645-9650.
[28]	DENG D, LEE J Y.Hollow core-shell mesospheres of crystalline SnO2 nanoparticle aggregates for high capacity Li+ ion storage.Chemistry of Material, 2008, 20(5): 1841-1846.
[29]	XU P F, YU R B, REN H,et al. Hierarchical nanoscale multi-shell Au/CeO2 hollow spheres.Chem Sci, 2014, 5(11): 4221-4226.
[30]	DEIVARAJ T C, CHEN W X, LEE J Y.Preparation of PtNi nanoparticles for the electrocatalytic oxidation of methanol.Journal of Materials Chemistry, 2003, 13(10): 2555-2560.
[31]	HUANG M H, JIANG Y Y, JIN C H,et al. Pt-Cu alloy with high density of surface Pt defects for efficient catalysis of breaking C-C bond in ethanol.Electrochimica Acta, 2014, 125(10): 29-37.
[32]	ZHOU Y, GAO Y F, LIU Y C,et al. High efficiency Pt-CeO2/ carbon nanotubes hybrid composite as an anode electrocatalyst for direct methanol fuel cells.Journal of Power Sources, 2010, 195(6): 1605-1609.
[33]	YU S P, LIU Q B, YANG W S,et al. Graphene-CeO2 hybrid support for Pt nanoparticles as potential electrocatalyst for direct methanol fuel cells.Electrochimica Acta, 2013, 94(1): 245-251.