Effect of pre-treatment approach of a carbon support on activity of PtSn/C electrocatalysts for direct ethanol fuel cells
Effect of pre-treatment approach of a carbon support on activity of PtSn/C electrocatalysts for direct ethanol fuel cells
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DOI：
10.1007/s10800-010-0253-0
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发表时间：
2011-04
影响因子：
2.9
通讯作者：
Jarupuk Thepkaew;S. Therdthianwong;A. Therdthianwong
中科院分区：
文献类型：
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作者：
Jarupuk Thepkaew;S. Therdthianwong;A. Therdthianwong
采用酸活化法和热活化法对Vulcan XC-72 R炭进行预处理，并将所得炭用作连续还原法合成PtSn/C催化剂的载体。采用物理N2吸附法、质量滴定法、酸碱滴定法和傅里叶变换红外光谱法对载体的BET比表面积、pHPZC和官能团进行了表征。采用X射线衍射仪（XRD）、能量色散X射线能谱仪（EDX）、电感耦合等离子体原子发射光谱仪（ICP-AES）和透射电子显微镜（TEM）对所制备的PtSn/C催化剂进行了表征，并考察了其在乙醇氧化反应中的行为以及在直接乙醇燃料电池（DEFC）中的性能。结果表明，硝酸预处理使载体表面产生了多种含氧官能团，提高了载体的酸性。酸处理载体的强酸性导致Pt还原反应的不利条件，并导致PtSn/C催化剂中Pt含量低但Pt：Sn比高。另一方面，热活化增加了碳表面上的碱性官能团，这增强了Pt前体的还原，并因此提供了2.2 nm的小的平均金属粒度。循环伏安法、计时电流法和电池性能测试结果表明，热处理后的碳载PtSn催化剂对乙醇氧化的催化活性和在直接乙醇燃料电池中的性能上级新鲜PtSn/C催化剂和酸处理后的碳载PtSn催化剂。
Vulcan XC-72R carbon was pretreated using acid and thermal activation methods, and the carbons obtained were used as supports for a PtSn/C catalyst synthesized by a successive reduction process. Surface characteristics of the supports, including BET surface area, pHPZCand functional group, were analyzed using physical N2adsorption, mass titration, acid–base titration, and Fourier transform infrared (FTIR) spectrometer technique, respectively. The prepared PtSn/C catalysts were characterized by X-ray diffractometer (XRD), energy dispersive X-ray spectrometer (EDX), inductively coupled plasma–atomic emission spectrometry (ICP–AES), and transmission electron microscope (TEM) techniques, and then were examined for their behavior under ethanol oxidation as well as for their performance in a direct ethanol fuel cell (DEFC). The results showed that pretreatment by HNO3produced various oxygenated functional groups on the support surface and increased its acidic property. The strong acidity of the acid-treated support led to an unfavorable condition for the Pt reduction reaction and resulted in low Pt content but high Pt:Sn ratio in the PtSn/C catalyst. On the other hand, thermal activation increased the base functional groups on the carbon surface, which enhanced reduction of Pt precursor, and consequently, provided a small average metal particle size of 2.2 nm. The results from cyclic voltammetry, chronoamperometry and cell performance testing confirmed that the catalytic activity for ethanol oxidation and the performance in the direct ethanol fuel cell of the heat-treated carbon-supported PtSn catalyst was superior to the fresh PtSn/C catalyst and the acid-treated carbon-supported PtSn catalyst.