金属掺杂聚吡咯碳化物PPY-M的制备及其氧还原反应电催化活性

doi:10.3724/SP.J.1077.2014.13275

摘要/Abstract

摘要：

在Fe³⁺或Co²⁺存在下进行吡咯的聚合反应, 得到金属离子掺杂的聚吡咯, 并在N₂气氛下700℃碳化, 再将该碳化产物在900℃焙烧得到含有不同金属的复合催化剂PPY-M(M为不同的金属)。采用SEM、XRD等对催化剂的结构进行了表征。通过循环伏安和线性电位扫描等电化学手段, 研究了催化剂对氧还原(ORR)的电催化活性及其稳定性。结果表明, 掺杂金属钴的催化剂的活性最好, 在酸性溶液中ORR的起始电位达到0.54 V(vs SCE),电流密度为7.5 mA/mg@-0.3 V(vs SCE); 在碱性溶液中ORR的起始电位为-0.11 V(vs SCE),电流密度为5.7 mA/mg@-0.8 V。Fe或Co掺杂的聚吡咯碳化物对ORR具有较强的电催化活性, 而且制备过程简单、成本低, 有较重要的研究意义。

关键词: 聚吡咯, 非贵金属催化剂, 氧还原, 燃料电池

Abstract:

Polymerization reaction of pyrrole in the presence of Fe³⁺ and Co²⁺ was carried out to synthesize the metal -doped polypyrrole (PPy). The metal-doped PPy was then calcined at 700℃ to obtain the carbonized products. Finally, the carbonized products were heated to 900℃ to synthesize the catalysts PPY-M(M is Fe or Co). The structure of the catalysts was investigated by SEM and X-ray diffraction techniques. The oxygen reduction reaction (ORR) activities of the catalysts in acidic and alkaline media were tested by voltammetry. Results show that the catalyst PPY-Co presents the highest electrocatalytic activity for ORR. The ORR current density at rotation rate of 2000 r/min is 7.5 mA/mg@-0.3 V(vs SCE) in acidic solution and 5.7 mA/mg@-0.8 V(vs SCE) in alkaline solution, and the onset potential of ORR is 0.54 V(vs SCE) in acidic solution and -0.11V(vs SCE) in alkaline solution. It is of great significance for the study of carbonizing products of PPY as efficient catalysts for ORR because of their simple preparation and low cost.

Key words: polypyrrole, non-precious metal catalyst, oxygen reduction reaction, fuel cell

中图分类号:

TQ174

张玉晖, 易清风, 刘小平, 向柏霖. 金属掺杂聚吡咯碳化物PPY-M的制备及其氧还原反应电催化活性[J]. 无机材料学报, 2014, 29(3): 269-274.

ZHANG Yu-Hui, YI Qing-Feng, LIU Xiao-Ping, XIANG Bai-Lin. Carbonizing Products of the Fe/Co Doped Polypyrrole as Efficient Electrocatalysts for Oxygen Reduction Reaction[J]. Journal of Inorganic Materials, 2014, 29(3): 269-274.

图/表 11

表1 不同催化剂中负载金属元素的质量分数

Table1 Mass percentage of metal in catalyst

Catalysts	PPY	PPY-Fe	PPY-Co	PPY-Fe-Co
Fe	0	4.6wt%	0	3.3wt%
Co	0	0	3.8wt%	2.7wt%

图1 不同催化剂的SEM照片

Fig. 1 SEM images of different catalysts

图2 不同催化剂的XRD图谱

Fig. 2 XRD patterns of different catalysts

图3 催化剂在N2饱和和O2饱和的0.5 mol/L H2SO4溶液中的循环伏安图, 扫描速率为20 mV/s

Fig. 3 Current-potential curves in N2-saturated and O2-satu rated 0.5 mol/L H2SO4. Scan rate at 20 mV/s

图4 催化剂在N2饱和和O2饱和的1 mol/L NaOH溶液中的循环伏安图, 扫描速率为20 mV/s

Fig. 4 Current-potential curves in N2-saturated and O2- saturated 1 mol/L NaOH. Scan rate at 20 mV/s

图5 催化剂在O2饱和的0.5 mol/LH2SO4溶液中的极化曲线图, 转速: 2000 r/min, 扫描速率: 5 mV/s

Fig. 5 RDE polarization curves of the samples in O2-saturated 0.5 mol/L H2SO4 at 2000 r/min and scan rate at 5 mV/s

图6 催化剂在O2饱和的1 mol/L NaOH溶液中的极化曲线图。转速: 2000 r/min, 扫描速率: 5 mV/s

Fig. 6 RDE polarization curves of the samples in O2-saturated 1mol/L NaOH at 2000 r/min and scan rate at 5 mV/s

图7 催化剂PPY-Co在O2饱和的0.5 mol/LH2SO4 (a) 和O2饱和的1 mol/L NaOH溶液 (b) 中不同点击转速下的极化曲线, 扫描速率: 5 mV/s

Fig. 7 RDE polarization curves of the PPY-Co at different rotation rates in O2-saturated 0.5 mol/L H2SO4 (a) and O2-saturated 1 mol/L NaOH (b). Scan rate at 5 mV/s

图8 不同催化剂在0.5 mol/L H2SO4(a)和1 mol/L NaOH(b)中的氧还原反应Koutecky-Levich图

Fig.8 Levich plots of various catalysts in 0.5 mol/L H2SO4 (a) and 1 mol/L NaOH (b)

表2 不同催化剂上氧还原的电子转移数

Table 2 Electron-transfer number of ORR on various catalysts

Electrolyte	PPY	PPY-Fe	PPY-Co	PPY-Fe-Co
Acid	1.8	2.4	3.4	2.5
Alkaline	1.5	2.7	3.2	2.1

图9 PPY-Co 分别在O2饱和的0.5 mol/L H2SO4 (0.2 V vs SCE) 和O2饱和的1 mol/L NaOH (-0.2 V vs SCE)溶液中的恒电位电解曲线

Fig. 9 Chronoamperograms of PPY-Co in O2-saturated 0.5 mol/L H2SO4 at 0.2 V (vs SCE) and in O2-saturated 1 mol/L NaOH at -0.2 V (vs SCE)

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