醇類還原法製備鉑錫合金觸媒沉積於碳、多孔碳及石墨烯載體其ORR活性之研究;Study on the ORR Activity of Platinum-tin Alloy Deposited on Carbon, Porous Carbon and Graphene by Alcohol Reduction Method

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Title:	醇類還原法製備鉑錫合金觸媒沉積於碳、多孔碳及石墨烯載體其ORR活性之研究;Study on the ORR Activity of Platinum-tin Alloy Deposited on Carbon, Porous Carbon and Graphene by Alcohol Reduction Method
Authors:	蘇竝堅;Su, Bing-Jian
Contributors:	機械工程學系
Keywords:	鉑錫合金觸媒;多孔碳(OPC);石墨烯;氧氣還原反應(ORR);醇類還原法;電化學穩定性;PtSn/C electrocatalysts;graphene;oxygen reduction reaction (ORR);Alcohol-reduction process;long-term stability;OPC
Date:	2018-08-17
Issue Date:	2018-08-31 15:04:55 (UTC+8)
Publisher:	國立中央大學
Abstract:	碳材料被廣泛用作催化劑載體，在本研究中，選擇碳黑、多孔碳(OPC)和石墨烯用做為PtSn合金觸媒之載體。並且以醇類還原法製備成陰極觸媒應用探討其氧氣還原反應(ORR)之活性。所製備觸媒之表面組成與形貌、化學組成、合金相、電催化活性及長時間穩定性分析，分別以場放射掃描電子顯微鏡(SEM)、X光繞射儀(XRD)、感應耦合電漿原子發射光譜分析儀(ICP-AES)、高解析度穿透電子顯微鏡(HRTEM)、熱重分析儀(TGA)、電化學分析儀器、及旋轉盤電極(RDE)分析與鑑定。在PtSn/C觸媒，高pH值的反應溶液中，所合成之合金顆粒具有二氧化錫 (SnO2)相，於反應溶液pH12條件下所製備之樣品具有較小之合金顆粒。儘管PtSn12樣品之Pt擔載量僅為商業材Pt/C的75%，由於觸媒表面上的氧氣吸附與解離增強，其ORR活化提高了1.31倍。此外，在加速劣化反應(ADT)測試後，PtSn12樣品之觸媒活性為商業材Pt/C之1.34倍，代表此樣品在酸性環境中更具化學穩定性。另外，在乙醇氧化反應測試，PtSn12樣品具有較佳之穩定性及耐CO毒化能力，表示SnO2能增強其EOR活性並使乙醇更容易完全氧化反應。OPC以模板法製備後再將Pt奈米顆粒乙醇類還原法沉積分散於其表面上，所製備之PtSn/OPC觸媒具有良好的顆粒分散性，其PtSn奈米粒子平均粒徑約2.7 nm。且其電化學活性表面積比商業材Pt/C高20%，此外，PtSn/OPC長時間穩定性亦優於商用Pt/C觸媒。以石墨烯做為PtSn之載體，由HRTEM結果可明顯觀察到PtSn合金顆粒均勻且分散性於石墨烯表面，其平均粒徑約為2.5 nm，經過ADT測試後，PtSn/G觸媒之保持穩定之起始電位，其ORR活性為商業材Pt/C之1.9倍，表示PtSn/C觸媒具有良好的化學穩定性及觸媒活性。本研究探討不同碳材料做為觸媒之載體，以醇類還原法所得之金屬觸媒具有較小之奈米粒徑，且良好的分散於載體表面上。由於合金觸媒具有SnO2，在電化學活性表現上，具有較佳之ORR及EOR活性，經過ADT測試後，其化學穩定性皆優於商業材Pt/C，並且保有較高之電化學活性。 ;Carbon material is widely used today as the catalyst support. In this study, carbon black, ordered porous carbon (OPC), and graphene were used as the catalyst support. The electrocatalysts were synthesized by using alcohol-reduction process and applied for the oxygen reduction reaction (ORR). The physical and morphological properties of the synthesized catalysts were characterized by energy dispersive spectrometer, X-ray diffraction, and high resolution transmission electron microscope. The electrochemical performances were analyzed by cyclic voltammetry, linear scan voltammetry and long-term durability. Results show that samples prepared at pH 12 have smaller particle size than those prepared at pH 9 due to the formation of SnO2 phases in PtSn/C catalysts. When the carbon support was added before the reﬂux process, the alloy nanoparticles having a size of 4.8 nm are uniformly dispersed on the C support. Although the Pt loading of PtSn12 is only about 75% of the commercial Pt/C, its ORR activity is promoted to 131% due to enhanced catalyst activity and O2 adsorption and dissociation on the catalyst surface. Furthermore, based on the accelerated durability test, the ORR activity after 500 cycles of PtSn12 is 1.34 times higher than that of Pt/C, suggesting that PtSn12 is more chemically stable in the acid environment due to the coexistence of SnO2 in PtSn/C. The Sn12 catalysts have better stability and poisoning tolerance suggesting that SnO2 plays an important role in enhancing the EOR activity and allowing ethanol oxidation to complete. The OPC is fabricated using template method. PtSn is deposited on OPC by the alcohol reduction method. Results show that PtSn/OPC as prepared has well dispersed Pt nanoparticles, with an average particle size around 2.7 nm. The electrochemically active surface area of PtSn/OPC samples is 20% higher than that of commercial E-Tek sample. Furthermore, the long-term stability of Pt/OPC is also better than that of commercial E-Tek sample. The nanoparticles were well-dispersed on the graphene support with an average size of 2.5 nm. The PtSn/G catalyst is more chemically stable in the acid environment than JM Pt/C.
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